Difficulties to combine biological degradation factors with artificial
weathering
Focussing on how to measure and evaluate
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
IntroductionIntroduction
Standardised methods:
• European: EN 927
• International: ISO
Problems: critical values
performance assessment
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
IntroductionIntroduction
Natural weathering, CEN/TC139/WG2:
• accelerated natural exposure
• Climatic Index
+ mimicry
- transfer of biological degradation patterns
Artificial ageing:
• UVS equipment (UV-CON, QUV with spray option)
• Wheater-O-meter (WOM)
+ fast
- physico-mechanical
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
IntroductionIntroduction
Solution:
combined or sequential testing of physico-mechanical and biological ageing
• short-term
• critical levels
• special focus on biological performance
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Weathering and assessmentWeathering and assessment
Natural weathering:
- mimicry
disadvantages:
• weather
• sample variability
- harmonisation of specimens and exposition
disadvantages:
• macro- and microclimate
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Weathering and assessmentWeathering and assessment
Artificial weathering:
• higher reproducibility
• more confidence in:
machines
ageing cycles
• less time consuming
• better control
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Weathering and assessmentWeathering and assessment
Assessment parameters:
• chalking
• flaking
• blistering
• cracking
• adhesion
Not necessary critical for all coatings
degradation phenomena on wood ‘missing’:
• biological
• erosion
• additional
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Weathering and assessmentWeathering and assessment
Needs for methodology:
• optimisation
• prioriy of parameters
• substrate:
hardwood softwood
porosity, vessel grouping
dimensional stability
extractives
• sample size: boards window frame corners
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Biological factorsBiological factors
Biological factors can be essential part of paint degradation:
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Biological factorsBiological factors
Biological factors can be essential part of paint degradation:
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Biological factorsBiological factors
Standard tests: prEN927 3-5, EN152
artificial weathering
Alternative tests:
• susceptibility
• fungal growth on, through, in the coating and the substrate
• impact analysis
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Biological factorsBiological factors
Additional parameters:
• film thickness
• water and water vapour permeability
• porosity
• surface roughness
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Blue stain testingBlue stain testing
Blue stain testing basics EN152:
+ WOM
• coating not on the vermiculite medium (contact with uncoated side)
• Aureobasidium pullullans and Sclerophoma pithyophila
• evaluation of surface blue staining and zone free of blue stain
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Blue stain testingBlue stain testing
Reversed method:
• coating on the vermiculite medium, other sides sealed
• Aureobasidium pullullans and Sclerophoma pithyophila
• evaluation of surface blue staining and interior presence of blue stain
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
Blue stain testingBlue stain testing
Internal presence of blue stain in service:
not just a blue free zone
Difficulties to combine biological degradation factors with artificial weathering - focussing on how to measure and evaluate
COST E18 Symposium
Copenhagen 16-02-2004
ConclusionsBlue stain testingBiological factorsWeathering and
assessmentIntro
Joris Van Acker – Imke De Windt – Jan Van den Bulcke
ConclusionsConclusions
- Modern coatings: low VOC + low biocidal content
- Increased impact of biological factors
- Yearly changes in impact of biological coating degradation
- Reproducible testing: artificial ageing + laboratory test method
- Artificial ageing should be specific for wood
- Wood coatings mainly fail due to moisture impact (swelling / shrinkage)
- Blue stain in service testing of coatings differs testing fungicidal impact
- Modern water- borne wood coatings should be able to
resist biological factors...
by means non-biocidal components or parameters...
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