Name: Mahler B
Message: Hi, I have a few headphones ear cushions made out of 'foam' that I want to dye black. What dyeing agents and methods should be used so that they won't 'bleed' once the color has set. Currently, I have hair dyes and Dylon permanent fabric dye. Will any of these work? Thanks a lot and happy new year!

Here is the link to the ear cushions (foam) that I am trying to dye the color black.

I do not know whether or not this a practical project to do at home. Your foam cushions are probably made of polyurethane, which may or may not be dyeable. I believe that dyes are normally added to the liquid from which the foam is produced. However, the foams can apparently be dyed after manufacture, because the company S & S Plastics <http://www.ssplastics.com/CustomFoamTreatments.html> advertises a service of dyeing foam. I don't know what sort of dye they use. Since I have not experimented with polyurethane foam myself, I cannot tell you what to do, but perhaps some of the information I can share will help you. I would very much like to know the results of any experimenting you do with this.

Polyurethane has the following chemical structure:
-CO-NH-CH2-CH2-NH-CO-O-CH2-CH2-O-
This is somewhat similar to the structure of Nylon, in that both contain an amide group:
Nylon (polyamide) -CH2-CH2-CO-NH-(CH2)6-NH-CO-CH2-CH2-
So, dyes that work on nylon might work on polyurethane.

The main dye classes to consider using are acid dye, fiber reactive dye, and disperse dye. Hair dye does not fit neatly into these classes, as there are different types, but it can be considered as acting much like acid dye.

Acid dye includes a wide range of dyes used on animal fibers such as wool, and also nylon, but, as a general rule, no other synthetic. Some are rather toxic, while others are so non-toxic that they are added to foods in large quantities. This might be worth a try. Does your foam show any signs of damage if you boil it in water? Acid dye requires warmth to attach to fiber. You can mail-order acid dye, or use unsweetened Koolaid, or even use all-purpose dye, which is readily available in stores. (All-purpose dye tends to give disappointing results on cotton, but works okay on wool and nylon.) Heat and a mild acid such as white vinegar are required.

Your hair dye could also be used to dye animal fibers such as wool, and also nylon, as nylon and wool have the same sort of dye sites as hair does. It also might be worth a try.

The fiber reactive dye class includes your Dylon Permanent Fabric Dye. It works very well on cellulose fibers such as cotton and rayon, and also works on silk, but is normally not used on other animal fibers or nylon, and does nothing at all to other synthetics. Fiber reactive dye can generally also be used as an acid dye, too, if it is used with an acid rather than the soda ash dye fixative normally used with this class of dye. It seems to me that this is the least likely type of dye to work for your project, however.

Disperse dye works on a number of different synthetic fibers, including polyester, nylon, acrylic, and acetate. If acid dye does not work, this would be the next type of dye to try. It seems to me to be the mostly likely prospect, but not as pleasant to use. You can mail-order it from PRO Chemical & Dye, which is an excellent source for all sorts of dye, or from Aljo Dye, which also carries a wide range of dyes.