Message: Hi, I'm wanting to dye an item that is 60% rayon and 40% rayon acetate. Is this possible? If so, what type of dye should I use? Thanks.

Although both are made from wood, rayon and rayon acetate are very different fibers. 

Rayon, also known as viscose, is similar to natural fibers such as cotton, and dyes beautifully and easily with fiber reactive dyes such as Procion MX dyes. See "How can I dye rayon?".

In contrast, acetate, also known as rayon acetate, has been chemically treated so that it is very much a synthetic fiber. Disperse dyes, which are also used for polyester and other synthetic fibers, were developed in order to dye acetate, because it is so unsatisfactory to attempt to dye acetate with any other dye type. Acetate does not dye well with other classes of dye.

I would recommend that you dye your item as you would if it were 100% rayon or cotton. Because only 60% of your item is made of rayon, you will end up with a color that is only 60% as intensely colored as a similar but 100% rayon garment would be. If you use a brilliant orange dye, you will get a softer orange, apricot, or coral color; if you use bright red, you will get pink; if you use purple you will get lavender; and if you use black, you will get a medium gray.

The advantage of this method, although the colors are not knock-your-eyes-out bright, is that the dyeing method is very easy, and it does not require special equipment such as a dyeing pot. Rayon can be dyed in cool water, in a bucket, or hand-painted with dye, or dyed via low water immersion. Cold water dyeing is kinder to any garment.

If you wish to dye both the 60% rayon and the 40% acetate in your garment, you will have to use different dyes and a more difficult dyeing procedure.

All hot water dyes require the use of a large non-reactive cooking pot, one which you will not plan to reuse for food, since textile dyes are not tested for safety and will contaminate food. The pot must be large enough for the fabric to move in freely, in order for you to obtain a smooth solid color. It must not be made of aluminum or iron, because these metals will corrode when heated with the soda ash or cid which is used to assist in dyeing; instead, it should be made only of stainless steel, or unchipped enamel. A large stainless steel cooking pot is an excellent investment if you will be using hot water dyes in the future, but it is too expensive to be worthwhile if this is the only dyeing project you plan.

It is possible to dye acetate with disperse dyes by heating the garment with disperse dyes on the stovetop,  at a simmering temperature just below a boil, for an hour. Constant stirring is necessary, so the procedure is a lot of work. You can purchase disperse dyes that are suitable for dyeing acetate from Aljo Mfg. Company, in New York. They sell a different range of disperse dyes for use on acetate than on polyester. See "Sources for Dyeing Supplies Around the World".

You may wish to dye the acetate in a completely different step from dyeing the rayon in your garment, or you can add some direct dye to the disperse dye bath in order to dye both acetate and rayon at the same time. The results may be unexpected, however. Also, direct dye is far less wash-resistant than fiber reactive dyes, and tends to run in the laundry.

Another important question is whether boiling will cause the rayon in your item to shrink. Even if a smaller size would be acceptable to you, a garment may pucker or lose its shape.

As you can see, it will be simpler to choose to ignore the acetate portion of the fiber in your item, and just use cool water fiber reactive dyes to dye the rayon a lighter color. The cooler water is less likely to damage the garment, the expense is much lower since you do not need a stainless steel dyeing pot, and you will not have to spend an hour over a steaming hot dyepot as you stir it.

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