Name: kiran
Message: polyester who is dieing to have the colour changed to black. a 'machine wash black dye' was used but unfortunately there were no changes made. could you please help me fix this big problem!!!!! thanks!

Polyester is completely different from natural fibers. Your Washing Machine Dye will work great on cotton, silk, rayon, or linen, but it can never do a thing to polyester.

The only kind of dye that will work well on polyester is called Disperse Dye. Disperse Dye can be used only on synthetics; it will just wash out of natural fibers such as cotton, silk, or wool.

Unfortunately, Disperse Dye is rather a pain to use for dyeing whole garments. It cannot be applied in merely hot water; it must be boiled, at length, say for an hour, with a special carrier chemical that makes up for the fact that even boiling water is really not quite hot enough.

You can buy disperse dyes from mail-order dye suppliers in many locations, including such companies as Fibrecrafts in the UK; I am not sure whether they sell the carrier chemical as well, which is required in order to get dark or intense shades when dyeing polyester. However, it is not enough to just buy the right kind of dye. You will need the right equipment, as well. You have to buy a very large non-aluminum pot, several gallons in capacity, large enough for your garment to move freely as it boils in the dyebath. Such a pot can be quite expensive, and yet you should not use the same pot for dyeing that you use for cooking, because textile dyes are not safe in food. Buying a large pot just for dyeing is a large expense for a dye novice, though it's an excellent investment for anyone who is serious about dyes.

You can make Disperse Dye iron-ons to add designs to your garment, but, although this is a great project in itself, it will not work for dyeing an entire garment a solid color.

The only other alternative for coloring polyester is to use a kind of fabric paint called pigment dye, which is not a dye at all. Like real dye, this can be used only to darken, never to lighten fabric. Look for any good fabric paint which claims to leave the fabric soft after painting; dilute the paint with a little water to immerse your garment in it. You will not be able to obtain a single smooth color over the whole garment with fabric paint, however; some parts will show the paint more, while others will show the original color.

For more information, see: "Dyeing Polyester with Disperse Dyes" and "Fabric Paints: a different way to color fibers".

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