Name: Shirley
Message: Hey Paula, I hope you can help me!?
I have just dyed some cotton fabric with a fibre reactive dye colour turquoise, thought I had followed all the instructions using soda ash as the fixer but when I got the cotton wet again all the dye started coming out so does not appear to have fixed properly.  I couldn't find anything on your site about re fixing after you have dyed it so not sure if it is possible to refix the dried dyed fabric again with more sofa ash?  If it is what should I do?  Many thanks, Shirley


It's possible that all is perfectly well in your case, and you are just seeing the excess unattached dye washing out of the fabric. Fiber reactive dyes on cotton are very different from acid dyes on wool; there is always a lot of unattached extra dye, which must be removed by washing. However, if almost all of the dye is washing out, you have a real problem. Maybe you left out the soda ash step.

A friend of mine did that once, dyeing cotton with Procion MX dyes without any soda ash at all. What she'd thought was soda ash was actually a urea solution (perhaps the person working with her may have gotten the two mixed up). So, what she did was she soaked the stuff in soda ash, just as you might do a presoak before tie-dyeing. You can use anywhere from one-third to one cup of soda ash per gallon of water.

You will need to take care of this as soon as possible. You want to do it before any more of the dye on the fabric hydrolyzes ("spoils") so that it cannot react with the cotton. 

When you put your dyed items into a bucket of soda ash, the dye that has dried on the fabric will run, and may transfer to other parts of the fabric, a real problem if you've been tie-dyeing or dye-painting. To reduce the amount of dye that dissolves in the soda ash solution, add a lot of salt, as much salt as you can possibly dissolve. This is called a saturated salt solution. If a little salt remains undissolved at the bottom, that's  fine. That's about 2.4 pounds of salt per gallon [4 liters]; use a little extra to be on the safe side. 

You can use this soda ash/saturated salt solution to soak your fabric in, or you can spray it on until the fabric is wet. Then the key is to allow time all over again for the dye reaction to progress, say overnight at 70° or higher. Maintain moisture during this time, either by using urea in the soda ash  mixture (one tablespoon per cup, or one cup per gallon), or wrap in plastic, so that the fabric does not dry out.

An alternative method, as described in the "Is there any alternative for soda ash?" section of my page on "What is soda ash, and what's it for in dyeing?" is to buy some sodium silicate solution, which is sold by Dharma Trading Company as AfterFix and as PRO Fix LHF and PRO QuickFix by PRO Chemical & Dye, as well as by other dye suppliers under other names. Sodium silicate works well, with its high pH, to activate the cotton to react with the dye. However, I don't think you should wait to order this stuff. Soda ash with salt should be fine. Don't bother to use salt if your fabric is a single solid color, as the salt is only intended to reduce dye transfer.

It is possible that your turquoise has begun to go bad in the jar. When fiber reactive dyes are in storage, they can, slowly, begin to react with tiny amounts of residual moisture. Once the dye has hydrolyzed, it will show the same behavior of refusing to fix to the cotton, even if soda ash is present and the temperature is adequate. Fiber reactive dyes last for a year or two after purchase, if stored in tightly closed jars, but they will go bad in a single day if stored in a hot enough place, such as a hot car in the sun. Please do a small test with your turquoise before you use it again. If this after-fixing works well, then you know it's okay. I must also mention that the Procion MX type turquoise is more temperature-dependent than the other colors in that series of dyes, so poor turquoise reaction often indicates inadequate warmth in the dye studio. Normally, any temperature over 70°F (21°C) is warm enough if you allow your dye reactions to progress long enough. 

Even after Procion MX and other fiber reactive dyes have completely hydrolyzed and are useless for dyeing cotton, they can still be used as acid dyes, on silk, wool, or nylon, if you substitute an acid such as vinegar or citric acid for the soda ash, and apply extra heat. See "Using Fiber reactive dyes on protein fibers". Acid dyes will not work on cotton, however.

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