Discharge Paste Techniques

Discharge, or color stripping, is the process of chemically removing color from previously dyed fabric. Fabrics dyed with reactive dyes will discharge to shades ranging from white to pastels to not at all, depending on the dye colors and discharging agent used. You will need to test dyed fabric with each discharge paste you plan to use in order to get semi-predictable results.

Discharging with Thiourea Dioxide Print Paste

To make a thiourea dioxide discharging paste for use on cellulose fiber, add 1 teaspoon of thiourea dioxide and 1 teaspoon of soda ash to 1/2 cup of thickened chemical water (dissolve the soda ash first in a small amount of hot water). Stir and dissolve the chemicals into the thickener, then print or apply the resulting discharge paste. This paste does not remain stable for extended periods of time.

While the discharge areas are still damp, remove the fabric from the printing surface and allow to dry, Steam iron the discharge areas to activate the discharge. Be sure to protect the iron and ironing board with paper towels! Wash and rinse the fabric thoroughly to remove the paste. Results obtained from this process will usually be quite different from those obtained with the chlorine bleach process.

Should you find it inconvenient to steam iron the fabric, similar results can be obtained by steaming the dry fabric for ten minutes.

Discharging with Rongalit Print Paste

There are two different formulations of rongalit discharging paste for use on cellulose fiber, one using soda ash to add alkalinity and the other using ammonia. Both give similar discharging results, must be steamed for best results and remain stable for extended periods.

The soda ash version uses 4 teaspoons of rongalit and 3/4 teaspoons of soda ash per 1/2 cup of thickened chemical water. Steam the dry fabric for ten minutes.

To make 1/2 cup of the version using ammonia, combine 2 1/2 teaspoons of rongalit, 3/4 teaspoons of ammonia, 5 grams of urea and 109 ml of water. Add the appropriate amount of sodium alginate for your intended use. Steam the dry fabric for ten minutes.

Discharging with Rupert Gibbon & Spider Discharge Paste

This paste is for use on natural fibers, is pre-mixed and remains stable for extended periods. While very convenient to use, it also smells slightly stronger than any of the above pastes. After the paste is dry you can either steam the fabric or steam iron it. Discharging results are similar to those obtained using rongalit print paste and steaming the fabric.

* Note: Use good ventilation when working with discharge!