TL;DR
Shade variation between batches is usually a dosing pump calibration error, a liquor ratio change, or a water quality change. Verify the liquor ratio and dosing accuracy before changing the recipe.
What you might see
- visual shade mismatch between batches
- colorimetric reading outside tolerance on spectrophotometer
- shade variation correlating with a water supply change
- dye consumption inconsistent across batches
Likely causes
Dosing pump calibration drift delivering incorrect dye concentration
Liquor ratio error from incorrect fabric loading weight or water fill volume
Water hardness or pH change between batches altering dye uptake
Fabric substrate variation between batches affecting dye affinity
Required tools
- Water pH meter and hardness test kit
- Graduated cylinder for dosing pump calibration
- Fabric weight scale
- Spectrophotometer for colorimetric verification
Safety first
- Many reactive and disperse dyes are skin sensitizers. Wear chemical-resistant gloves when handling dye solutions.
- Dye bath liquors at high pH (for reactive dyes) or low pH (for acid dyes) are corrosive. Wear eye protection and an apron when opening the vessel for sampling.
Procedure
- 1
Weigh the fabric batch before loading and verify it matches the recipe specification. A weight deviation of more than 2% changes the effective liquor ratio.[1]
- 2
Verify the water fill volume by checking the machine level sensor reading at the fill target.
- 3
Test the water pH and hardness with test strips or a meter. Adjust with a water softener or pH correction chemical if the values are outside the recipe specification.
- 4
Check the dye dosing pump calibration by running a timed delivery into a graduated cylinder and comparing to the programmed dose volume.[1]
- 5
Recalibrate the dosing pump if the actual volume deviates more than 2% from the set volume.
- 6
Review the temperature profile log for the previous batch. A temperature deviation during the critical dye fixation phase can cause shade variation.
- 7
Run a color swatch trial with the corrected parameters before committing to a full production batch.
Sources
Thies Thies iMaster H2O Dyeing / Finishing Range general technical documentation, Thies
Thies iMaster H2O dyeing machine general batch reproducibility and dosing procedures (general)
More guides for Thies Thies iMaster H2O
How to fix dye bath temperature deviation on a Thies iMaster H2O
Temperature deviation is usually a failed heating element, a blocked heat exchanger, or a thermocouple calibration drift. Check the heating system and sensor calibration before adjusting the recipe.
How to clear a fabric rope tangle or knot in a Thies iMaster H2O
Fabric rope tangles are usually caused by over-loading the vessel, an impeller speed mismatch, or a fabric join failure. Clear the tangle manually, check the load weight, and verify transport speed.
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