Name: Sally
Message: Hi,
I am trying to dye a 100% cotton sweater from white to red.  I was told that to not shock the fibers and shrink the sweater I need to slowly raise the temperature of the dye bath and slowly cool it off.  Is this true, and would I heat the dye bath to dissolve the dye then cool it and put the sweater in and then heat it up again slowly? Thanks!

No. Although gradual changes in temperature may be less risky than sudden changes, what you should do is use a cool water dye, and avoid using a hot dyebath altogether. There is no reason to use a hot water dye on a cotton sweater when cool water dyes give better results and allow you to avoid the risk of shrinkage altogether.

Do not use a hot water dye such as Rit brand all-purpose dye on a cotton sweater. Instead, mail-order some cool water fiber reactive dye, such as Procion MX dye. There are many different retail sources from which you can order your Procion MX dye; see my list of Sources for Dyeing Supplies Around the World, or you can order through Amazon using my Color Chart for Buying Procion MX Dyes through Amazon. You will also need soda ash and salt for immersion-dyeing your sweater with this type of dye, which you can do in a large bucket, rather than a washing machine, if you prefer. Procion MX type dyes will work at 70°F (21°C) or above.

Although hot water is best for the washing-out stage of removing excess unattached reactive dye from fiber, after the dyeing process is complete, you will of course still want to avoid its use. Wash several times in lukewarm water so as not to shrink the cotton, leaving it to soak for a while at some point in the process, and then in the future wash separately from other colors until all excess unattached dye has been removed. This takes much longer in cool water than in hot water. The final result will be much longer-lasting and brighter in color if you use fiber-reactive dyes instead of inferior all-purpose dyes.


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