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Creating markets for recycled resources

Development of colour indicator techniques to detect chemical contamination in wood waste for recycling Project code: WOO0034

Date of commencement of research: 18th October 2004 Finish date: 17th March 2005

Written by: Mr. Gervais Sawyer and Dr. Mark Irle

Forest Products Research Centre

Buckinghamshire Chilterns University College, High Wycombe, Buckinghamshire,

HP11 2JZ

Published by: The Waste & Resources Action Programme The Old Academy, 21 Horse Fair, Banbury, Oxon OX16 0AH Tel: 01295 819900 Fax: 01295 819911 www.wrap.org.uk

WRAP Business Helpline: Freephone: 0808 100 2040

Date (published) June, 2005

ISBN: 1-84405-204-4

WRAP Ref: 013WOO

http://www.wrap.org.uk/

Table of Contents DEFINITIONS ..............................................................................................1

EXECUTIVE SUMMARY.................................................................................2

ACKNOWLEDGEMENTS ................................................................................3

1. INTRODUCTION ...................................................................................4

2. ACTIVITY AND RESULTS.......................................................................4

2.1. INITIAL INDICATOR ASSESSMENT ...................................................................................4 2.1.1. Detection Threshold ..................................................................................................5 2.1.2. False Positives.........................................................................................................12

2.2. INDICATOR OPTIMISATION...........................................................................................14 2.2.1. Chromazurol ...........................................................................................................14 2.2.2. PAN .......................................................................................................................18 2.2.3. Experiments on thickening agents.............................................................................19 2.2.4. Final Formulations ...................................................................................................20

2.3. FIELD TRAILS ...............................................................................................................21 2.3.1. Application Methods ................................................................................................21 2.3.2. Sites Visited ............................................................................................................23 2.3.3. Verification .............................................................................................................27 2.3.4. Indicator Storage Stability ........................................................................................29

2.4. HEALTH AND SAFETY ISSUES ........................................................................................29 2.4.1. Material Safety Data Sheets .....................................................................................29 2.4.2. Labelling.................................................................................................................30

3. CONCLUSION......................................................................................31

APPENDICES ............................................................................................................................32

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Definitions

Abbreviation Definition

As arsenic

CCA Copper-chrome-arsenic (a wood preservative now restricted to industrial use)

Cr chromium

CS Chromazurol S (a colour indicator of copper)

Cu copper

PAN 1-(2-pyridylazo)-2-naphthol (a colour indicator of copper)

TBTO tributyltin oxide ( a previously used wood preservative)

XRF X-ray fluorescence

Colour indicator techniques to detect chemical contamination in wood waste 1

Development of colour indicator techniques to detect chemical contamination in wood waste for recycling Executive Summary

This project developed a practicable method of detecting preservative-treated wood that can be used at wood recycling facilities and other situations. The method uses either of two indicators: chromazurol S (CS) and PAN (1-(2-pyridylazo)-2-naphthol). The active ingredients in these indicators are chelating agents that react with copper (Cu). These indicators can, therefore, detect copper-based preservatives, e.g. copper-chrome-arsenate (CCA). In volume terms, the various CCA formulations and other Cu-based preservatives have been used most often to treat wood in the UK. Consequently, an indicator that can identify Cu would be of significant help to recycled wood processors and users.

This report is divided into three sections. The first section describes laboratory work on characterising initial versions of the indicators. From this it was possible to develop alternative versions of the indicators with improved performances. This work is described in the second section. The final section describes the field trials that were conducted with the improved indicator formulations.

New formulations of CS and PAN indicators were developed that give results in 5 to 45 seconds. This is far faster than was possible with the original formulations and speed is important in the field. It is anticipated that operatives will prefer the PAN formulation because it is quicker. In the field, however, CS seems to be more reliable as the PAN indicator gave a number of false positive colour changes. Consequently, there is a case for using both indicators because if both give a positive result, then the conclusion should be that Cu is present in the piece of wood tested. If only one indicator gives a positive result, then this suggests that there are metals present, but, not necessarily Cu.

The costs of either indicator solution are similar. Both indicators are cheap to produce. It should be possible to develop kits that are cheap enough for them to have widespread use. The cleanliness of recycled wood, and thus the assurance that recycled wood products are free of chemical contaminants, would be greatly improved if chemically treated wood could be identified and segregated at source. These kits could assist inexperienced operators, i.e. those at a demolition site for example, to sort wood into treated and non-treated piles. Certainly, it is foreseen that these kits would be useful to all wood recycling facilities and companies that use recycled wood in their products.

Spray application is most attractive, but small brush applicators may be more appropriate for sorting at source. The spray method is very quick and with careful aim, several pieces can be assessed with one “shot”. In terms of assessing a large storage pile of recycled wood, the spray system was found to be the most efficient.

Brush application is the most economical in equipment and use. It is slow, however, and the risks of operator contamination are higher. If assessments are made occasionally, then the brush is likely to be the most appropriate because of its ease of use and economy. If regular assessments are to be made then the spray, or possibly the Weedstick, would be more appropriate.

Both formulations are safe if used following the guidance in this document, and require no special controls.


Acknowledgements

The work in this project could not have been achieved without the financial support of WRAP (Waste & Resources Action Programme) and the kind assistance of the following:

A & A Recycling Services Ltd. Bentley Sawmill, Coleshill Road, Bentley, Warwickshire CV9 2HJ. Tel: 01827 722300 Fax: 01827 715155 Email:[email protected]

Arch Timber Protection Ltd. Wheldon Road, Castleford, Yorkshire, WF10 2JT

Bledlow Civic Amenity Site Wiggans Lane, Bledlow Ridge, Buckinghamshire, HP14 4BH

Grundon Waste Management Ltd. S GRUNDON (Ewelme) Ltd., Goulds Grove, Ewelme, Wallingford, Oxon, OX10 6PJ Tel: 01491 834311 Fax: 01491 832272 Website: http://www.grundon.com/

Osmose Protim Solignum Ltd. Fieldhouse Lane, Marlow, Buckinghamshire. SL7 1LS Tel: 01628 486 644 Fax: 01628 476 757 Website: http://www.osmose.co.uk

Sutton District Council Civic Amenities Site Oldfields Road, Sutton, Surrey, SM1 2NS Tel: 0208 770 5070

Wastecycle Ltd. Private Road No 4, Colwick Industrial Estate, Nottingham, NG4 2JT. Tel: 0115 940 3111 Fax: 0115 940 4141 E-mail: [email protected] Website: www.wastecycle.co.uk


http://www.grundon.com/

http://www.osmose.co.uk/

http://www.wastecycle.co.uk/

1.

2.

Introduction

This project aims to assist wood recyclers and others in the improved management of wood waste, in particular the better segregation of clean and contaminated wood waste prior to it being reprocessed. Much has been done to improve mechanical reprocessing and cleaning processes but segregation prior to this step would help wood recyclers assure their customers of clean product. What is needed is a practicable method of detecting preservative-treated wood that could be used at wood recycling facilities and other situations. This project is concerned with the development and use of chemical indicators to help identify preservative-treated wood in waste streams. It was decided at the outset of the project to focus attention on the two indicators identified as having potential by another project funded by WRAP called CLEAR1; these two indicators are CS (chromazurol S) and PAN (1-(2-pyridylazo)-2-naphthol). The active ingredients in these indicators are chelating agents that react with copper (Cu). These indicators can, therefore, detect copper-based preservatives, e.g. copper-chrome-arsenate (CCA). In volume terms, the various CCA formulations and other Cu-based preservatives have been used most often to treat wood in the UK. Consequently, an indicator that can identify Cu would be of significant help to recycled wood processors and users.

The research presented in this report is divided in to three sections. The first section describes laboratory work on characterising the existing indicators. From this it was possible to develop alternative versions of the indicators with improved performances. This work is described in the second section. The final section describes the field trials that were conducted with the improved indicator formulations.

Activity and Results

2.1. Initial Indicator Assessment Trials were first carried out at the laboratory level so that development could occur in a controlled environment. Wood blocks, on which to conduct the trials and assessments, were carefully sawn from untreated, virgin sources of Scots pine (Pinus sylvestris) and spruce (Picea spp). The nominal size of these blocks was 3 mm thick, 40 mm wide and 40 mm long (parallel to grain). No particular orientation was chosen and so the faces of these blocks were a mixture of radial and tangential faces. The small thickness was chosen to ensure complete penetration of preservative when applied.

2.1.1. Detection Threshold

In order to assess the detection threshold of the indicators, wood blocks were treated with CCA solutions of different strengths. Initially a stock solution of CCA Celcure oxide was made up to 8%2. Dilutions of 4%, 2%, 1%, 0.5% and 0.25% were made up from the stock. The dilute solutions were used to assess whether the indicators will successfully detect Cu in weathered pieces of treated wood in which the level of Cu may have depleted over the years.

Eight pieces each of Scots pine and spruce were subjected to a vacuum of –0.8 bar for 10 minutes and then immersed in each solution for 5 minutes. They were then sealed in bags and heated at 70 °C for 60 hours in order to fix3 the CCA. Four of the test pieces were then oven dried and the remainder were stored wet to allow indicator tests to be conducted on both dry and wet timber. This was done because it is likely that, in practice, many of the timber pieces to be assessed at recycling facilities will be wet.

The starting point with this current project was to use the indicator formulations used during the CLEAR project. These initial formulations were used to assess the detection thresholds of each indicator. The “standard” solution of CS consisted of:

1 Project number WOO3-007[0]. The final report can be found at http://www.wrap.org.uk/publications/SamplingContaminantsPBD.pdf2 This is the highest solids content and maximum strength that might be used for a commercial treatment. Typical strength for building applications would be 2%. 3 CCA is an effective preservative because the components bond to the wood. In commercial situations, the bonding process, known as fixing, takes time (weeks), but, it can be accelerated by heating.


http://www.wrap.org.uk/publications/SamplingContaminantsPBD.pdf

Component Weight (g)

Distilled or deionised water 94.5

sodium acetate 5.0

chromazurol S 0.5

And the “standard” solution of PAN consisted of:

Component Weight (g)

Methanol 99.95

PAN 0.05

The indicators were applied by brush to the previously treated wood blocks. Two replicates of each combination of species, preservative level and state (dry or wet) were observed. Figure 1 and Figure 2 show the colour changes observed on dry wood blocks and Figure 3 shows the same tests repeated on wet blocks.


Figure 1 The colour change of “standard” solutions of CS and PAN indicators applied to dry pine and spruce blocks both untreated and treated with 0.25 and 0.5% CCA solutions.


Figure 2. The colour change of “standard” solutions of CS and PAN indicators applied to dry pine and spruce blocks previously treated with 1, 2, 4 and 8% CCA solutions.


Figure 3 The colour change of “standard” solutions of CS and PAN indicators applied to wet pine and spruce blocks previously treated with 0.25, 0.5, 1, 2, 4 and 8% CCA solutions.


The reaction time of PAN is generally faster than for CS in that the colour change occurred within 20 seconds as opposed to three to four minutes for the CS.

In general, the colour change was greater and easier to discern on dry blocks rather than on wet blocks. This is demonstrated by the limit of detection observed. For CS, the limit would appear to be around 0.5% CCA strength when the wood is wet and 0.25% when dry for both Scots pine and spruce; although the colour change is more distinct on the spruce blocks. Interestingly, adequate colour changes did occur after 24 hours, even at the lowest concentration, which is a very sensitive reaction. Note that the photographs of the blocks were taken some hours after the application of the indicators and so the colour change is stronger than that observed in the first 5 minutes. It is considered that, to be effective in the field, the indicators must give a result within a minute.

The colours that developed were measured using the Lovibond colour comparator system that matches, on a split viewing screen, the observed colour with coloured filters overlaid on a standard white block. This method allows a colour to be broken down in to red, yellow, blue and brilliance levels. There were two reasons for assessing the colour changes in this way: to determine if any patterns existed that may provide a semi-quantitative measurement of the Cu level present; and to specify a colour filter which would enhance the contrast between a positive and a negative result. It was considered that enhancing the colour change may help during use in real-world situations where light levels may be low and where wood colour may mask the indicator changes.

Table 1 shows the colour measurements made on wood blocks that had not been treated with CCA. Both CS and PAN indicators increase the Red and Yellow levels, but, the CS decreases Blue and Brilliance values whereas the PAN increases these.

Table 1. Lovibond colour measurements on wood blocks with out any preservative treatment.

Lovibond Colour Species Indicator Red Yellow Blue Brilliance

Scots pine None 2.7 3.0 0.6 1.0 Scots pine CS 4.9 10.0 0.0 0.0 Scots pine PAN 4.5 10.0 0.8 2.0 Spruce None 2.4 3.0 0.2 1.0 Spruce CS 4.9 10.0 0.0 0.0 Spruce PAN 4.7 4.9 0.5 2.0

Both indicators cause distinct colour changes when applied to CCA treated wood blocks. The data collected for spruce are presented in Table 2 and those for Scots pine blocks in Table 3. No definite patterns were detected in the data presented in these tables and these data were obtained under ideal conditions. Consequently, no further assessment via the Lovibond system was used in this project.

The PAN indicator worked well on both wet and dry blocks and is able to detect all the concentrations of CCA investigated. The colour changes were observed to be greater on end-grain than on the faces. This may be a result of greater concentrations of CCA being present on the end grain.


Table 2. The reaction time and colour recorded of CS and PAN applied to CCA treated spruce blocks.

Lovibond Colour CCA Strength Indicator Block

State ReactionTime (s) Red Yellow Blue Brilliance

8% None Dry 3.0 7.0 2.5 0.0 8% CS Wet 180-240 4.7 6.0 6.6 0.0 8% PAN Dry 20 5.5 4.2 3.1 0.0 8% PAN Wet 20 4.8 4.2 3.2 0.0 4% None Dry 2.5 5.0 1.4 0.0 4% CS Dry 180-240 6.0 12.0 8.6 0.0 4% CS Wet 120-180 3.1 7.0 5.4 0.0 4% PAN Dry 15 5.2 4.2 3.1 1.0 4% PAN Wet 10 6.1 4.3 3.7 0.0 2% None Dry 2.5 4.0 1.2 0.0 2% CS Dry 240 5.0 12.0 9.6 0.0 2% CS Wet 240-300 3.5 7.2 5.7 0.0 2% PAN Dry 15 6.2 4.2 3.1 1.2 2% PAN Wet 10 4.5 4.0 1.4 0.0 1% None Dry 2.1 3.3 0.4 0.1 1% CS Dry 240 6.0 11.0 7.7 0.0 1% CS Wet 240 7.0 12.0 9.8 2.0 1% PAN Dry 15 6.2 4.2 3.1 1.2 1% PAN Wet 20 5.6 2.0 1.3 0.0 0.50% None Dry 0.50% CS Dry 240 5.0 12.0 5.0 0.0 0.50% CS Wet 300 8.0 12.0 7.7 2.0 0.50% PAN Dry 10 5.0 2.0 1.3 0.0 0.50% PAN Wet 30 6.1 2.0 1.1 0.0 0.25% None Dry 1.0 2.0 0.0 0.0 0.25% CS Dry 240 poor 5.0 12.0 3.5 0.0 0.25% CS Wet nil 6.2 12.0 6.3 2.0 0.25% PAN Dry 20-30 5.0 3.0 1.0 0.0 0.25% PAN Wet 30 6.0 2.0 1.1 0.0

When tested against copper naphthenate preservative (Cuprinol) the colour development is almost immediate (Figure 4). This is probably because the Cu is not so tightly bound to the cell wall. Copper naphthenate is a metal soap of copper and naphthenic acid. The Naphthenate soaps are attractive to end users because of their very low mammalian toxicity. Zinc naphthenate and its derivative acypetacs zinc are now more widely used as they do not have the colour bleed through problems of the copper product. However, it is well known as the "Cuprinol" brand. It may have a revival since the decline in creosote, and since pentachlorophenol is declining in the USA, copper naphthenate is performing well for utility poles. Typical application rates are 5% in an oil fraction. Light organic oils are used for domestic and heavy oils for utility work.


Table 3. The reaction time and colour recorded of CS and PAN applied to CCA treated Scots pine blocks.

Lovibond Colour CCA Strength Indicator Block

State ReactionTime (s) Red Yellow Blue Brilliance

8% None Dry 4.3 10.0 3.3 0.0 8% CS Dry 240+ 0.6 11.0 6.0 0.6 8% CS Wet 180-240 5.4 9.0 8.2 0.3 8% PAN Dry 20 7.7 7.7 4.2 0.0 8% PAN Wet 20 5.1 3.5 3.1 0.0 4% None Dry 5.3 10.0 2.7 0.0 4% CS Dry 180-240 6.0 12.0 8.0 0.0 4% CS Wet 180-240 5.0 8.4 8.2 0.0 4% PAN Dry 15 6.7 5.7 3.0 0.0 4% PAN Wet 10 6.3 4.5 2.7 0.0 2% None Dry 3.6 6.0 1.0 0.0 2% CS Dry 240-300 6.0 12.0 7.0 0.0 2% CS Wet nil 5.3 7.7 4.2 0.0 2% PAN Dry 15 6.5 5.1 2.8 0.0 2% PAN Wet 10 6.8 4.9 2.3 0.0 1% None Dry 5.9 10.0 3.0 0.2 1% CS Dry 300+ 6.0 10.0 6.0 0.0 1% CS Wet 240 5.3 7.7 4.2 0.0 1% PAN Dry 15 7.7 5.2 7.7 0.0 1% PAN Wet 20 5.4 2.0 1.1 0.0 0.50% None Dry 1.2 3.0 0.4 0.1 0.50% CS Dry 300 poor 4.6 7.0 2.5 0.0 0.50% CS Wet nil 8.5 7.1 3.0 0.0 0.50% PAN Dry 10-20 6.1 3.0 2.0 0.0 0.50% PAN Wet 30 5.7 2.5 0.3 0.0 0.25% None Dry 1.6 3.3 0.1 0.1 0.25% CS Dry 240 poor 4.7 11.0 3.8 0.0 0.25% CS Wet nil 8.7 7.1 1.3 0.0 0.25% PAN Dry 20-30 7.0 7.0 1.3 0.0 0.25% PAN Wet 30 6.2 3.0 0.1 0.0

Figure 4. The colour change observed when the indicators were applied to blocks of spruce and Scots pine previously treated with copper naphthenate.

The overall conclusion of this section of work is that in ideal conditions both indicators are very sensitive to Cu, although the reaction times vary significantly. Certainly, either indicator can detect commercially treated CCA wood and, from limited trials with pre-treated timber, wood treated with other copper-based preservatives.


2.1.2. False Positives

Some laboratory trials were conducted on the possibility of false positive results. These could occur in practice because most of the near transition metals, e.g. iron, nickel, zinc, etc., react with the indicators to give bright and lurid colours. Fortunately, however, most of these are unlikely to be found in recycled timbers because they are not used in preservation or surface coatings.

PAN will react to zinc and tin. Zinc could occur as corrosion products of galvanised fixings as well as from organic wood preservatives and tin could be present from TBTO (tri-butyl tin oxide a wood preservative). However, when tested against TBTO at the usual concentration of 1%, it did not detect it. It would appear that a concentration of about 50% is necessary for a reaction, which is unlikely to occur in wood for recycling. Consequently, based on these laboratory tests zinc from corrosion products was considered as the only likely false positive result for the PAN indicator in practice.

From the laboratory tests conducted CS was found not to be so reliable when it comes to false positives because it reacts (in time) to a number of metals including iron rust. Its reaction to road salt is of most concern, giving a dark brown colour. Fortunately, this is very different to the colour change caused when Cu is present. One option would be to recommend that both indicators are used to confirm the presence of Cu-based preservatives. However, additional work on false positive results was conducted during the field trials and this is described in section 2.3.3.


Table 4. The colour changes caused by substances that are not Cu-based wood preservatives.

Colour Change for CS Colour Change for PAN False positive substances

Potential Source Spruce Pine Spruce Pine

Iron hydroxide

corrosion products (rust)

slight brown

light magenta

none

none

Zinc chloride corrosion products

pinky brown

pinky brown

magenta

magenta

Cobalt chloride

unlikely to be found

light olive blue

light olive blue

magenta

dark magenta

Tin chloride unlikely to be found

dark magenta

magenta

light tan

light tan

Nickel sulphate

unlikely to be found

mauve

violet

light mauve

light mauve

Tributyltin oxide (TBTO)

wood preservative

tan

tan

pink

very pale pink

Sodium chloride road salt

pinky tan

light tan

pale orange

tan/orange


2.2. Indicator Optimisation Many wood preservatives contain copper or another metal such as zinc or tin, although the latter was phased out of commercial use some years ago. Manufacturers must make the preservative as permanent in the wood as possible, whilst not losing biocidal activity. Exterior woodwork that is preservative treated is exposed to rain and high humidities. The preservative must, therefore, be resistant to leaching by water. Preservatives that are applied as water soluble solutions, e.g. CCA, must undergo some change prior to being placed in service in order to minimise their leachability. In the case of CCA, the copper is tightly bound to the wood cell walls by the presence of chromates. An alternative strategy is to formulate the preservative as an organic compound of copper or zinc such as a naphthenate soap. These are insoluble in water but soluble in organic solvents and thus resist leaching.

The principal difficulty in devising an indicator for copper in wood preservatives is to uncouple the bound copper so that it can react with the indicator. The indicator formulation must also wet the cell walls, swelling them so that the largest reaction area possible is exposed. Secondly, the correct buffer or chelating agent must be used in sufficient quantity to enable the desired reaction to occur.

The new formulations described in this section were tested by applying them to CCA treated wood blocks. Following the work on detection limits, a CCA solution strength of 1% was used for the treatment. The wood blocks were treated as described in 2.1.1, with the exception that the preservative treatment was fixed for just 48 hours at 70 °C and all the blocks were dried prior to testing.

2.2.1. Chromazurol

The original CS formulation was entirely aqueous. Even though wood is hydrophilic it is not always readily wettable with water. Indeed some preservative formulations contain water repellents to enhance their performance and these will interfere with the wetting of the original CS formulation.

The logical step was to make the formulation with an organic solvent that wets wood more readily. Consequently, polar solvents, principally alcohols, were tested.

CS and the sodium acetate buffer are only soluble in water, so initial attention was paid to determining the minimum amount of water that could dissolve the CS and sodium acetate required. This solution could then be diluted with alcohols and tested for optimum performance.

2.2.1.1. Sodium acetate buffer ratio

The proportion of sodium acetate buffer in the standard aqueous formulation was varied above and below the standard 5%, i.e. 2.5%, 10%, 20% and 40%. The optimum reaction time was achieved with 10% sodium acetate buffer. The results are shown in Figure 5.


Figure 5. The effect of varying sodium acetate content on colour development on CCA treated spruce blocks.

2.2.1.2. Water ratio

A minimum practical amount of water was needed to dissolve the CS and sodium acetate. It was found that a ratio of 26 g of water to 10 g of sodium acetate and 0.5 g of CS was adequate.

2.2.1.3. Addition of polar solvents

Since methanol is good at swelling the wood cell walls, it was the first of the alcohols to be tried. A great improvement in the wetting action was observed but the reaction time of the indicator was slowed. This trial was followed by trials with ethanol, n-propanol, iso-propanol, butanol and hexanol. Since the higher alcohols are unacceptably toxic, they were not explored further.

Ethanol is attractive owing to its relative safety, although some slight improvement could be obtained with n-propanol. No improvements in reaction time were obtained with higher alcohols although the lower volatility was attractive for use in hot weather.

Through experiments on the dilution of the indicator with alcohol it was determined that 40 g of ethanol was found to provide the optimum wetting whilst maintaining indicator reaction time, see Figure 6.

Other polar solvents trialled were acetic acid, formamide and 2-ethoxyethyl acetate. Of these, only formamide gave any reaction and that was to give an instant deep blue colouration to the mixture.


Figure 6. The effect of varying the ethanol content of CS solutions on the colour change observed when applied to 1% CCA treated wood blocks. 2.2.1.4. Increasing viscosity

If used in very hot conditions, the solvents may flash dry before the indicator reactions have taken place. Furthermore, a liquid of such low surface tension can be easily atomised resulting in a risk of splashing and spray drift. The simplest and cheapest option was to add monoethylene glycol. Further experiments were begun using


rheological thickening agents, on which further details are given later. Optimum addition level of monoethylene glycol, in terms of minimising splashing without affecting reactivity, was determined as being 33 g content, see Figure 7.

Figure 7. The results from a rapid version of the original CS indicator.

The use of carboxymethyl cellulose, a widely used food additive, to thicken the mixture was promising at ratios up to 20%. After prolonged storage, however, this component was found to precipitate out at temperatures approaching 0 °C. Consequently, it is insufficiently reliable for everyday use.

2.2.1.5. Chromazurol concentration

In the interests of economy of constituents, the proportion of CS was investigated. If time to develop the colour were not an issue, the concentration could be reduced to as low as 0.125%, but in order to achieve the most rapid and high contrast results a 0.5% concentration is found to be best, see Figure 8.

2.2.1.6. Alternative buffers

From experiments on the leaching of CCA from wood4, it is clear that acetates, citrates, acetic acid and citric acid significantly increase leaching. This implies that these compounds loosen the hold of the components of CCA to the wood cell walls. Accordingly, indicator solutions were tried using these buffers that may be more effective at releasing copper. The use of citric acid caused an instantaneous red colouration of CS that was irreversible. When repeated with a sodium citrate adjusted to the same pH as sodium acetate, there was no reaction in the presence of copper. Likewise, combinations of acetate and citrate were tried and at slightly different pH levels, but with no improvement in reactivity. As a result, sodium acetate was kept as the buffer for the CS formulation.

4 COOPER, P. (1991). Leaching of CCA from treated wood: pH effects. Forest Products Journal 41, 30-32.


Figure 8. The effect of reducing the concentration of CS indicator concentration on the colour developed when applied to CCA treated wood blocks.

2.2.2. PAN

PAN is in a powder form that tends to clump. It is only soluble in polar alcohols and even then takes some time to dissolve; gentle warming and a long period of stirring is required to fully dissolve it. Work was therefore directed towards finding a balance between alcohols and water that would provide wetting and reactivity without too much volatility in hot weather.

2.2.2.1. PAN concentration

Starting with the standard formulation, it was first determined whether there was a benefit in increasing the concentration of the solution. Accordingly the concentration of PAN was increased by small increments from 0.05% to 0.3% to determine the optimum. The best balance between reaction time and economy was determined at to be 0.1%, see Figure 9.

2.2.2.2. Alternative solvents

As for CS, a full range of alcohols was tried, i.e. methanol, ethanol, n-propanol, iso-propanol, butanol, pentanol and hexanol. The higher alcohols improved the reaction time, i.e. reduced it, as did ethanol, however, a combination of methanol with n-propanol gave a good improvement in reaction time. As for CS, the addition of some monoethylene glycol enhanced the performance of the indicator by slightly increasing viscosity and limiting splashing. The use of methylcellulose as a thickening agent, although initially promising, proved to be unstable.


Figure 9. The effect of reducing the concentration of PAN indicator concentration on the colour developed when applied to CCA treated wood blocks.


2.2.3. Experiments on thickening agents

Rheological thickening agents are widely used in the food and paints industries, to name but two. Their use in the indicator formulations was explored with a view to developing a non-drip formulation that could be used in domestic applications such as disposable “dab-on” gels or home testing kits.

Almost any solution can be thickened, whether aqueous, petroleum solvent or polar solvent. Furthermore, particularly with aqueous solutions, they can be given thixotropic properties, which is to say that they can alternate between being a paste and a liquid just by agitation.

Since the CS formulation was largely an aqueous formulation, it was decided to try a thixotropic clay known as Laponite. This is a synthetic clay, inert and neutral where the addition of as little as 0.5% can form a fully non-spillable solution that is quite fluid if brushed onto a surface. The process of determining the correct concentration of Laponite with a water/alcohol system was very time consuming, and there was a tendency for the alcohol to separate from the water component of the mixture. A CS gel was made eventually using 1% Laponite.

A strange effect was noticed when a CS gel was applied to CCA treated wood, in that the colour development was adjacent to the applied gel and not underneath it. It may be that the active CS is retained within the clay platelets of the gel and hence immobilised somewhat. Overall, the results are promising and clearly worth further exploration, however this was outside of the scope and timescale of this project..

Non-aqueous solutions cannot be thickened with Laponite clay. Instead a polymer system such as Carbopol®

should be used. Most Carbopol® polymers are high molecular weight homo- and copolymers of acrylic acid cross-linked with a polyalkenyl polyether. When first mixed they have quite a low viscosity and indeed a low pH of approximately 2.5. As the pH is increased by adding sodium hydroxide or ethylene diamine, the viscosity increases greatly, but if the pH is raised too much, the viscosity will fall off again.

The indicator mixtures are sensitive to pH, so adjusting the thickening medium to be compatible is crucial. The experimental difficulty in determining the quantities of each component is that very extended mixing is required before a stable pH is reached after any neutralising agent added. During the time of this project, it was not possible to determine the precise formulation, but it is recommended as a necessary piece of future research in order to develop domestic versions of these indicator reagents. It should be noted that these thickening agents present no health hazards and indeed are common components of toiletries and cosmetics.

2.2.4. Final Formulations

2.2.4.1. Chromazurol

The optimal formulation for the CS indicator, in terms of reaction time and splash resistance, consists of the following components:

Component Quantity

chromazurol S 0.5 g

Distilled or deionised water 26.0 ml

sodium acetate 10.0 g

ethanol 40.0 ml

mono-ethylene glycol 33.0 ml

The indicator can be made as follows: add the CS to the water, warm gently and stir until fully dissolved. Slowly add the sodium acetate and stir until dissolved. Add the ethanol and mono-ethylene glycol, stir, and allow to cool. Store in a sealed container in a cool, dark place.


2.2.4.2. PAN

The optimised formulation for the PAN indicator, in terms of reaction time and splash resistance, contains:

Component Quantity

PAN 0.1 g

methanol 40.0 ml

n-propanol 40.0 ml

mono-ethylene glycol 10.0 ml

distilled or deionised water 10.0 ml

To make the indicator, first dissolve the PAN in the methanol and stir. Warm gently. Avoid excessive heat because the flash point of methanol is only 11 °C. Ensure that there are no ignition sources when warming or preparing solutions. In addition, it is strongly recommended that preparation of the indicator is carried out in a fume cupboard. When fully dissolved, allow to cool, and then add the n-propanol, mono-ethylene glycol and water. Mix and store in tightly closed container.

2.2.4.3. Temperature effects

All laboratory tests on the indicator formulations were carried out at the ambient temperature which was a nominal 20 °C. In order to be satisfied that the formulations could perform in real life situations, they were also tested in situations where wood and reagents were at -5 °C and at +30 °C. In the first case, this was done by transferring all equipment to a large chest freezer set at -5 °C. The higher temperature was achieved in a large laboratory oven. No difference in indicator performance was noted, which was a little surprising as the higher and lower temperatures would be expected to raise and depress the reaction time.

It was during this test that it was noted that carboxymethyl cellulose thickened formulations showed a tendency to precipitate at low temperatures.

2.3. Field Trails The two indicators described above in section 2.2.4 were used in “real-life” situations to assess their usefulness in an industrial environment. The aim was to see if the indicators continued to perform well outside of a laboratory environment. Three main factors were explored: the most appropriate application method, the speed of reaction and the visibility of the colour change.

2.3.1. Application Methods

2.3.1.1. Aerosols

According to contacts in the aerosol industry almost any application can be catered for. Consequently, it should be possible to have a specific aerosol manufactured for the indicators and their intended use. The difficulty is how to specify exactly what is needed. Once designed, the advantages of an aerosol are: safe handling, convenience and efficacy. On the other hand, the disadvantages are: a large (thousands) minimum batch production size is required; it is difficult to see when the can is almost empty; and the empty container represents a disposal problem.

It was not possible to have an aerosol made for the field trials and so this application method would have to be the subject of an additional development study, although it must be said that this application method is unlikely to prove to be the most favourable.

2.3.1.2. Hand Sprayer

A high quality hand sprayer like that shown in Figure 10 was used during the field trials. If used correctly, these sprayers offer very little risk of operator contamination through drips, drift, leakage, etc., and the spray pattern gives perfect wetting with one quick shot. Low quality hand sprayers that can be used to spray water on to plants are not sufficiently safe for use with the indicators.

Good quality sprayers are: relatively cheap, robust, stable, have a good capacity and one can easily see contents. The actual sprayer used during the trial was not ideal, however, because the nozzle should be modified for this purpose. The standard design needs lengthening, securing and angling downwards so that it is less vulnerable to damage and directs the spray in the most convenient direction.


Figure 10. Good quality hand sprayers like that shown on the left can be used to apply the indicators. Low quality sprayers like that on the right are not appropriate.

The sprayer was used to apply the PAN indicator during the trials. PAN and CS are not compatible and so the sprayer would have had to be cleaned thoroughly before refilling with CS indicator (and vice versa). Since flushing out the sprayer on site was not deemed practicable, only the PAN indicator was used with the sprayer. However, CS indicator has the same spraying characteristics and can b way.

sy to

oint,

skip without climbing in

e as 0.06 ml for

l y

solution. This would increase the capacity and eliminate the need to dismantle the applicator end for

The Weedstick ply the CS solution during the field trials.

e used in the same

2.3.1.3. The Weedstick

The Weedstick is a device for applying weed killer directlyon to weeds with little risk of contaminating surroundingplants. When the head is depressed in to the ground acontrolled quantity of weed killer is ejected on to the plant it is pushed against. According to the manufacturers, the Weedstick is: light to carry, eause and economical. Plus there is no risk of drift. Generally, the experience gained during the field trials supports these statements. Certainly, there is no risk of drift because the applicator is very close to the test pand some feet away from the operator. In fact, the length of the Weedstick is an advantage because it increases the reach of the operator, thus making it possible to reach all points in a and reaching the tops of piles.

The version used was slightly modified by attaching a small sponge to the tip. At each depression of the tip, the device delivered a 2 ml shot of indicator solution in to the sponge. This is excessive and should be altered so that it delivers only 1 ml of indicator, possibly less. It isonly necessary to dampen a small area with the indicator. Brush application may apply as littl

Figure 11. The Weedstick, used by manygardeners around the world.

satisfactory results (see section 2.3.1.4).

A disadvantage of the Weedstick as used, is that it is difficult to charge with indicator. Protective gloves were essential. It is not particularly robust in its present form and is unlikely to withstand the rigours of an industriasituation without considerable modification. The British manufacturers are very proactive, however, and maconsider such modifications. The ideal solution would be to modify the tube to accept a screw on bottle of indicatorfilling.

was used to ap

2.3.1.4. Brush

Application with a brush is certainly possible and cheap. It is considered that the indicator solutions should be thickened to minimise the risk of dripping and “flicking” during application. Success at thickening the solutions


with methyl cellulose was achieved, but, it was later found that the storage life of these solutions was too short. Consequently, monoethylene glycol was added to the optimised indicators to increase their viscosities and redevaporation of the solvents. Experience of applying the indicators by brush

uce in the laboratory and in the field,

application is chosen, then there needs to be further work on making a

0 ml) dispensers

nufactured for the application of solvent type adhesives and have vapour-tight covers to prevent loss of solvent.

A brush dispenser.

however, suggests that a thicker, thixotropic gel would be more suitable.

Thixotropic gel versions of the indicators were successfully made to the point where an open beaker of the gel could be inverted without any spillage of indicator. When applied to wood, however, the gel prevented properpenetration of the active ingredients and so no colour change could be seen except around the edges of theapplication area. Clearly, if a brush viscous solution or thixotropic gel.

Further work is also required on the actual application method. Although a brush is simple, there is a strong possibility of contamination of the operator as experience with common paint testifies. A purpose designed brushapplicator may be better at minimising operator contamination and improving portability. A brush dispenser like that shown in Figure 12 might be suitable. It would need a leak-proof cap. Small capacity (5-1are readily available. They offer the greatest economy of reagent and are easily disposed of.

Larger capacity brush applicators could be produced. Dispensers like those shown in Figure 13 are ma

Figure 12.

Schematic of aFigure 13 large capacity brush dispenser

A simple analysis of the costs of using either of the two indicators is given below:

Method per Test per Test

2.3.1.5. Costs

Quantity Cost

Spray 1 – 2 ml ≤ 2 p

Weedstick 1 – 2 ml ≤ 2 p

Brush ≈ 0.08 ml ≤ 0.1 p

These costs are based on the direct costs of the chemical components only. The costs would be increased if one takes in to account, the manufacture, storage and packaging of the indicators, plus the cost of the applicator. Othe other hand, bulk purchase of the components would reduce costs. The quantity of actual indicator in each

n

ion of the overall volume and so the costs are dominated by the carrying solvents. mix is only a small proport

2.3.2. Sites Visited

Four different recycling facilities were visited during the trials. These are situated in the towns of: Sutton, Radcliffe, Ewelme and Bentley. The aim was to trial the indicators in situ on a range of different types and


sources of waste wood in different conditions in order to ensure that they are reliable and practical for use by wood recyclers.

It is worth no tes. In particular, those sites managed

In the main, it processes domestic waste. It is a very

yard. Pieces of timber obtained on varnished

timber. These and other positive results ection 2.3.3).

nds. The site was muddy at the time of the visit and this,

The wood found here was very mixed. It included construction and demolition waste, garden furniture, pallets etc. Some of the wood was very dirty, i.e. soiled, which makes the colour of stains more difficult to discern.

ting the generally positive attitude of the staff at the four siby the recycling companies showed strong interest in the project and saw it as a useful step forward.

2.3.2.1. Oldfields Road Reuse & Recycling Centre, Sutton

The Oldfields Road Reuse & Recycling Centre run by Sutton District Council was selected because of this Borough’s commitment to high levels of waste recycling. busy facility, with little capacity for sorting wastes into different categories. Wood found at this site included: decking off-cuts, fencing, joinery, and kitchen furniture.

The site is managed by SITA. Deliveries of scrap timber were collected at one point in the suspected of containing preservatives were tested there. Unexpected positive results were

were sampled for analysis (see s

Conditions were cold and wet and sufficiently dark to preclude the taking of photographs.

2.3.2.2. Grundon Waste, Ewelme Nr Benson, Oxon.

This facility is well equipped for handling wastes of all kitogether with wood being recovered after screening to remove earth and other wastes, results in some quite dirty waste wood (Figure 14) and chips (Figure 15).

Figure 14 lts ay on to mixed waste wood as delivered to the site. Note: t uares show negative PAN result and the circles positive results.

The resu of the PAN indicator sprhe white sq


Figure 15 The results of PAN and CS indicators on waste wood recovered from screening operations. Note: white square shows negative PAN result and triangle a positive CS result.

2.3.2.3. Wastecycle, Radcliffe

This company accepts construction and Civic Amenity waste. Wood is separated out by hand and then roughly chipped for the particleboard industry. The waste comes from a 50 mile radius. At the time of the visit, there were a lot of pallets in the waste stream; this is shown in Figure 16. The Figure also shows the advantage of the spray system. The pile has been tested at a number of points in quick succession. No other technique gives such a rapid and easy assessment. Some unexplained colour changes were obtained (Figure 17), later shown to be a reaction to small quantities of iron in gypsum plaster and cement (see section 2.3.3). Site conditions were cold, wet and windy.


Figure 16. Waste wood awaiting processing at Wastecycle Ltd. Radcliffe.

Figure 17. Unexpected positive reactions to PAN

2.3.2.4. A & A Recycling, Bentley, Warwickshire

This site combines pallet repair with wood recycling. A large proportion of the recycled wood is derived from pallets that are uneconomic to repair. Very little treated wood was seen during the visit, but, it was present. For example, a piece of fencing treated with Celbronze, a version of CCA that has a stain to make it look like creosote was found. The Celbronze treated piece can be seen in the centre of Figure 18. The dark surface of the treated wood makes it difficult to see the colour change and so it is best to cut the surface in order to see the reagent colour change. The easiest way to cut a corner off a piece of wood, like that shown, is to use an adze, which is an axe that cuts at right-angles to the shaft in stead of parallel to it. Any other cutting tool would suffice, however.


Figure 18 Examples of waste wood found at A&A Recycling that caused a colour change in the two indicators.

Other positives in Figure 18 come from a piece of decking (top centre with positive “dabs” of CS and a spray of PAN). The ladder, bottom centre, also gave a positive result with PAN and this is discussed in the following section.

2.3.3. Verification

The optimised version of the PAN indicator provides very rapid, almost instant results, but, there do seem to be more false positives compared to the CS indicator. In this section, data are presented on the metals found in pieces of wood that were unlikely to be treated but which still showed a positive result. Suspicious pieces were collected and analysed in the laboratory using XRF (X-ray fluorescence) analysis. The results are summarised in the table below.


Table 5. A summary of elements found by XRF analysis and colour change observed by the indicators.

No Description Indicator Colour

Developed Elements found Conclusions

1 Varnished softwood PAN Red Zinc Could be a preservative basecoat

2 Varnished softwood PAN Red Zinc Could be a preservative basecoat

3 Green oak PAN none Calcium Clean. Cement contamination 4 Joinery PAN Slight red Iron and manganese Inconclusive 5A Ladder PAN Slight red Iron Dirt! Inconclusive

5B Ladder reverse face PAN none Nil Clean

7 Green spruce CS Dark blue Copper only Copper quaternary ammonium or azole

8 Creosote coloured spruce CS Dark blue

Copper chromium & arsenic CCA – Celbronze

9 Sadolin finish on softwood PAN

Slight red on clean

wood Zinc & iron Inconclusive

10A Green chipboard PAN Slight red Trace iron. Calcium

& sulphur Plaster 10B Whitewood PAN Pink None unexplained

11 Green decorative stain

PAN & CS None None organic

12 Plaster PAN Pink Calcium, sulphur,

iron Unexplained. 13 Dirty whitewood PAN Magenta Calcium only Cement?

14 Joiney PAN Carmine

red Zinc Acypetacs zinc or zinc naphthenate

15 Joiney PAN Carmine

red Zinc Acypetacs zinc or zinc naphthenate

16 Softwood. Dirty PAN Magenta Copper chromium

arsenic CCA

From Table 5 it can be seen that zinc is the element which caused the unexpected colour changes when PAN indicator was used. Although zinc is not a metal of any concern, it is associated with Acypetacs and naphthenate preservatives. At the moment, the particleboard manufacturing industry would not consider results 1, 2, 7, 8, 14 and 15 as false positives because their material supply specifications exclude ALL preservative treated wood; even wood preservatives that are not considered hazardous. Small amounts of iron appear to give a red colouration. This seems to be associated with pink gypsum plasters and cement as the latter often contains small quantities of iron.

CS indicator did not give any false positive results. This is contrast to the results obtained in the laboratory where it was found that CS will give a colour change when different metals are present given sufficient time. Possibly because of the cooler temperatures and shorter observation times, false positive results were not obtained during the field trials.

A cautious approach to separating preservative treated wood from non-treated wood would be to exclude all wood that caused a colour change. The argument in favour of this is that there must be some contamination present to cause the change and in order to maximise the quality of recycled wood they should be excluded. On the other hand, the inclusion of some wood treated with acypetacs in to a raw material stream for, say, particle-board manufacture, is unlikely to cause any health or environment risks. Another, approach would be to use both indicators; if both give a positive result, then Cu is very likely to be present.

2.3.4. Alternative Application Method

The field trials demonstrated the viability of using colour indicators in an industrial situation. Although the spray and Weedstick methods were effective for applying the indicators both methods have disadvantages, particularly with regard to potential operator contamination either in use or during refilling. It would be beneficial if the


indicator could be supplied to the end-user in a cheap, ready and simple to use form. A novel idea was considered and briefly investigated at the end of the project, which involves the use of felt-tip pens to apply the indicator.

Figure 19. The use of a felt-tip pen to apply CS indicator. The picture on the left was taken immediately after applying the indicator and the one on the right 60 s later.

Figure 19 shows very clearly that a felt-tip pen can be used to apply the indicators. The technology for solvent-based ink pens exists and the manufacture of these is likely to be a cost effective option. Their use is intuitive to everyone who has used a pen before. The risk of contamination should be no more likely than when using permanent ink pens.

When empty the pens could be returned to the supplier for refilling or disposal.

2.3.5. Indicator Storage Stability

A bottle of each indicator of a “standard” formulation, i.e. the original formulation, was made at the start of the project and was assessed 14 weeks later. The indicators were stored in less than ideal conditions, i.e. in daylight at ambient temperature. No loss of activity was found, both indicators performed as before.

Although this is not a conclusive test it does demonstrate that the indicator solutions can be stored for relatively long periods without affecting their use. Conducting longer tests were not possible within the project because of the duration of the project itself.

None of the individual components of the indicators require special storage conditions to prolong their lives. There is no reason to suspect that the combination of ingredients would present the need for special storage conditions.

Note that the optimised formulations, which contain organic solvents, should be stored in fire resistant cupboards.

2.3.6. Guidance for Users

The salient facts on the manufacture, storage and use of the two indicators in this report have been extracted to form two separate guidance notes for use; one for the optimised CS indicator and the other for the PAN.

The aim of these guides is to provide just the relevant information on the indicators and not on how the information was derived.

The user manuals will be published by WRAP as supplementary information to this report.

2.4. Health and Safety Issues The indicators developed in this project contain organic solvents, which in some situations can cause health and environmental risks. In addition, very little is known about the actual indicator ingredients themselves. This section therefore considers health and safety issues associated with the use of these indicators.

2.4.1. Material Safety Data Sheets

Health and safety information on the individual components of the indicators have been obtained via Material Safety Data (MSD) sheets offered by suppliers of the components. At least two MSD sheets have been found from different suppliers of the components in order to verify the data. All the ingredients could be supplied by two different companies, VWR International and Fisher Scientific UK, and so these are presented in Appendix 1.


The advice on the actual indicator chemicals, CS and PAN, is limited. In a sense, this is evidence that these two substances are not considered dangerous. More concrete evidence comes from the MSD sheets:

MSD sheets from Fisher state: “No information found” for Chronic health effects; neither chemical is listed for carcinogenicity; and neither chemical is listed as hazardous.

The information contained in the MSDs was used to prepare MSD sheets for the indicator solutions. Two methods have been used. One using the Lycos hazard safety data evaluation and label making software (see Appendix 2) and the other was prepared manually (see Appendix 3). Lycos is a powerful program, and does in minutes what would take weeks by hand.

Although at first glance these sheets may seem alarming, they are typical for many bulk chemicals. They should be regarded as generic examples that can be refined if commercial versions of these indicator solutions are developed and place on the market.

Both indicator solutions contain organic solvents and so the main risks are fire and inhalation of vapours. These risks can be minimised by considering the factors immediately surrounding the area where the indicator will be used; by avoiding ignition sources for example. Details of the risks and first aid measures are given in the MDS sheets in Appendices 2 and 3.

2.4.2. Labelling

The Chemical Hazard Information and Packaging regulations (CHIPS) specify the requirements for information on product hazards and the format of package labelling. The opportunity of using the LYCOS software allowed the preparation of labels that meet the CHIPS regulations and which could be used on the packaging of the indicator solutions. An example is given in Figure 20. The inclusion of methanol and propanol in the formulation makes the indicators a fire hazard and a potential poison.

Figure 20 A dummy label suitable for the packaging of the PAN indicator solution.

During the identification of risks a number of other important factors were identified that should be considered prior to commercial production or use of the indicators. Appropriate packaging would have to be selected and used with the indicators and this may affect the MSD sheet. Plus, there is the issue of the flash point of the indicators. Methanol has a flash point of only 11 °C but if it were to rise to above 20 °C when blended with all the other, less flammable, components, it may simplify the use and control of the indicator solutions. Unfortunately, there was insufficient time to measure the flash point of the final formulations and so this should be determined prior to commercialisation.

Organic chemical residues are generally regarded as special waste. Incineration in a high temperature incinerator is the recommended method of disposal for unused quantities of either indicator. This can be achieved via a competent chemical disposal company.


3. Conclusion

This project has clearly demonstrated that chemical indicator solutions can be used in industrial situations for the identification of Cu-based preservative-treated wood in waste streams. More specifically:

1. CS and PAN formulations now give results in 5 to 45 seconds. This is far faster than was possible with the original formulations. Speed is important in the field because pieces must be sorted quickly.

2. Recyclers and operatives are likely to prefer PAN because it is quicker. In the field trials, however, CS was more reliable. There is a case for using both indicators. The PAN indicator could be used first, because it is the faster of the two, and then the CS could be used a cross check on any positive PAN results. If both give a positive result, then the conclusion should be that Cu is present in the piece of wood tested. If only one indicator gives a positive result, then this suggests that there are metals present, but, not necessarily Cu.

3. The costs of either indicator solution are similar and both indicators are cheap to produce. It should be possible to develop kits that are cheap enough for them to have wide spread use. The final cost would be dependent on the chosen application method.

4. The cleanliness of recycled wood would be greatly improved if wood was sorted at source. These kits could assist inexperienced operators, i.e. those at a demolition site for example, to sort wood in to treated and non-treated piles. Certainly, it is foreseen that these kits would be useful to all wood recycling facilities and companies that use recycled wood in their products.

5. Spray application is most attractive, but small brush applicators may be more appropriate for sorting at source. The spray method is very quick and with careful aim, several pieces can be assessed with one “shot”. In terms of assessing a large storage pile of recycled wood, the spray system was found to be the most efficient because the technique is quick and applied to many different parts of a stock pile to obtain an overall estimate of potential preservative content.

6. Brush application is the most economical in equipment and use. It is slow, however, and the risks of operator contamination are higher. If assessments are made occasionally, then the brush is likely to be the most appropriate because of its ease of use and economy. If regular assessment are to be made then the modified spray, or possibly the modified Weedstick, would be more appropriate.

7. It is recommended that the development of a felt-tip pen to apply the indicators should be investigated further. As this has the potential to be used by anyone with little training, including the general public. The pens could be made available at Civic Amenity sites to help ensure that treated wood is sorted at source.

8. Both formulations pose little risk if used following the guidance in the MSD and this document.


Appendix 1

Material Safety Data Sheets of Indicator Components


Appendix 2

Example Material Safety Data Sheets of Indicator Solutions Derived Through LYCOS Software


Appendix 3

Example Material Safety Data Sheets of Indicator Solutions Prepared Manually


MATERIAL SAFETY DATA SHEET Chromazurol Indicator Solution PURPOSE. For the rapid identification of copper containing preservatives in wood.

APPLICATION. Apply to a cut surface by special applicator, brush or low atomisation spray. A deep blue colour develops within a minute. Intended for use outdoors, or indoors with fume extraction.

If used as directed, there is a low risk of exposure. Stable at room temperatures.

Components

Chemical components: CAS Number

Chromazurol-S 1667-99-8

Ethanol 64-17-5

Sodium acetate 127-09-3

Monoethylene glycol 107-21-1

General hazard data Flammable. Do not expose to naked flames. May cause skin, eye and respiratory irritation. Harmful if swallowed. In the event of fire, use water, powder or foam extinguisher.

Risk management Avoid skin contact by using appropriate applicator or by wearing protective gloves. Do not use in confined areas. Store in a cool place. In the event of spillage, use spill absorbent material and package for proper disposal. Product will evaporate moderately quickly.

First Aid Measures Eyes. Flush with plenty of water for 15 minutes. Seek medical attention.

Skin. Flush with water. Remove affected clothing.

Ingestion. Seek medical attention. Call poisons control centre. If victim is conscious, give 2-4 cupfuls of milk or water.

Inhalation. Remove victim to fresh air. Give oxygen if necessary.

Advice on constituent chemicals Chromazurol-S. Not listed as a hazard, but may cause skin and eye and respiratory irritation.

Ethanol. Causes severe irritation to eyes, gastrointestinal tract and skin. Can also cause drowsiness and nausea. Can cause chronic effects.

Sodium acetate. No specific hazards, but may cause mild eye, skin gastric and respiratory irritation.

Monethylene glycol. May cause moderate eye and skin irritation. Ingestion may cause nausea and vomiting. Can cause respiratory irritation, headache and irregular eye movement. May cause chronic kidney injury.

Disposal Incineration in a high temperature incinerator is the recommended method of disposal of unused indicator.


MATERIAL SAFETY DATA SHEET PAN Indicator Solution PURPOSE. For the rapid identification of copper containing preservatives in wood.

APPLICATION. Apply to a cut surface by special applicator, brush or low atomisation spray. A magenta colour within a few seconds. Intended for use outdoors, or indoors with fume extraction.

If used as directed, there is a low risk of exposure. Stable at room temperatures.

Chemical components: CAS Number

1-(2-pyridylazo)-2-naphthol (PAN) 85-85-8

Methanol 67-56-1

Monoethylene glycol 107-21-1

Propan-1-ol 71-23-8

General hazard data Flammable. Do not expose to naked flames. May cause skin, eye and respiratory irritation. Harmful if swallowed. In the event of fire, use water, powder or foam extinguisher.

Risk management Avoid skin contact by using appropriate applicator or by wearing protective gloves. Do not use in confined areas. Store in a cool place. In the event of spillage, use spill absorbent material and package for proper disposal. Product will evaporate moderately quickly.

First Aid Measures Eyes. Flush with plenty of water for 15 minutes. Seek medical attention.

Skin. Flush with water. Remove affected clothing.

Ingestion. Seek medical attention. Call poisons control centre. If victim is conscious, give 2-4 cupfuls of milk or water.

Inhalation. Remove victim to fresh air. Give oxygen if necessary.

Advice on constituent chemicals PAN. Not listed as a hazard, but may cause skin and eye and respiratory irritation.

Methanol. Causes moderate irritation to eyes and skin. Can also cause drowsiness and nausea. Can cause chronic effects.

Monethylene glycol. May cause moderate eye and skin irritation. Ingestion may cause nausea and vomiting. Can cause respiratory irritation, headache and irregular eye movement. May cause chronic kidney injury.

Propan-1-ol. Causes moderate irritation to eyes and skin. Can also cause drowsiness and nausea. Can cause chronic effects.

Disposal Incineration in a high temperature incinerator is the recommended method of disposal of unused indicator.


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