SOUTHEAST UNIVERSITYDEPARTMENT OF TEXTILE ENGINEERING

KNIT DYEING FAULTS & REMEDIES

EXAMPLE OF DYEING FAULTS

Uneven dyeing.

Running shade.

Batch to batch shade variation.

Patchy dyeing effect.

Roll to roll variation or Meter to meter variation.

Crease / Wrinkle mark.

Dye spot.

Softener mark.

Fabric hole.

UNEVEN DYEING.

Causes:

• Uneven pretreatment (uneven scouring & bleaching).

• Improper color dosing.

Remedy:

• By ensuring even pretreatment.

• Proper dosing of dyes and chemicals.

Patchy dyeing effect.Causes:

• Faulty injection of alkali.

• Due to improper salt addition.

Remedy:

• Proper dosing of dyes and chemicals.

• Heat should be same throughout the dye liquor.

Roll to roll variation or Meter to Meter variation:Causes:

• Poor migration property of dyes.

• Improper dyes solubility

Remedies:

• Use standard dyes and chemicals.

• Proper m/c speed.

PATCHY DYEING EFFECT.

Causes:

• Faulty injection of alkali.

• Due to improper salt addition.

Remedy:

• Proper dosing of dyes and chemicals.

• Heat should be same throughout the dye liquor.

ROLL TO ROLL VARIATION OR METER TO METER

VARIATION:

Causes:

• Poor migration

property of dyes.

• Improper dyes

solubility

Remedies:

• Use standard dyes

and chemicals.

• Proper m/c speed.

BATCH TO BATCH SHADE VARIATION

Causes:

Shade variation can be as a result of mixing of the fabrics of two different lots.

Shade variation is also caused by the variation in the process parameters i.e. Time, Temperature & Speed etc. from one fabric roll, to the other.

CONT...

Remedies:

Ensure that the grey fabric used for one shade is

knitted from the same lot of the yarn.

Ensure that the same process parameters (Width,

Overfeed, Temperature & Machine Speed etc.)

are used, for each roll of a dye lot.

SOFTENER MARK:

Causes:

• Improper mixing of the Softener.

• Improper running time of the fabric during

application of softener.

Remedies:

• Maintaining proper reel sped & pump speed.

• Proper Mixing of the softener before addition.

FABRIC HOLE.

causes:

• More acid of knit

fabric in the dyeing

section.

• Temperature highly.

Remedy:

• Use standard Acid.

• Proper dosing of

Acid.

PIN HOLE DAMAGE:

Causes: Oxidation of the knitting

oil/lubricant on the fabric stored for a long duration.

Presence of sharp metallic part in some parts of machine

Presence of heavy metal ions in peroxide bath.

Remedies: Check presence of any

sharp object in machine Provide magnetic filters in

water/ steam line

CREASE MARK:

Causes: More cycle time. Faulty plaiting device. Slack on tight selvedge causes

creases at an angle to each selvedge.

Incorrectly set bowed-expander. Variation of heating and cooling

rate. Improper fabric movement.

Remedy: Anti- creasing agents are used to

avoid crease mark problem.

DYE SPOTS

Causes:

These are most often caused by operators not correctly mixing and thoroughly dissolving the dyestuff, in the right amount of water.

Dye bath hardness.

Not agitation of dyestuff.

Remedies:

Use adequate amount sequestrate to lower bath hardness.

Proper agitation.