Name: Ronna
Message: Dear Paula,
I have a white dress that is 65% rayon and 35% acetate. I would like to dye it red. What dye would you recommend?

Viscose rayon, which is what we generally call rayon in the US, is a cellulose fiber which dyes just like cotton, but even more brilliantly. I prefer to dye it with cool water fiber reactive dye, such as Procion MX dye. Rayon lasts better when not treated with hot water, and these are the brightest and most colorfast of dyes for cellulose fibers. Do not use all-purpose dye on rayon, as the heating that is required for a good attachment between all-purpose dye and fiber will be destructive to the fragile rayon material.

Acetate is much more difficult to dye than cotton and rayon. To dye acetate, you would use disperse dye, the same dye used to dye polyester. As a general rule, it is best to ignore the acetate portion of this blend, and dye only the rayon portion. The undyed acetate fibers will remain white, and will reduce the brightness of your results, as compared to dyeing an item which is made of 100% rayon. Results can still be good, however.

Rayon/acetate garments are often labeled "dry clean only". You cannot dye something that is truly not washable, but you can often wash garments that are labeled this way by hand in cool water, taking care not to twist or wring the fabric. Rayon tends to be quite weak when wet, and it is then much more liable to tear or fray, so you must be careful and gentle with the fabric. Before dyeing your dress, prewash it; if it survives the prewashing process, you can go ahead and dye it.

For mail-order sources of Procion MX and other cool water fiber reactive dyes, see my list of "Sources for Dye Supplies".