Name: John

Message: I’ve been scouring the web for a solution to my dilemma but haven’t turned up anything conclusive. I found your web site and you seem to know an awful lot about coloring fabrics, so I was hoping you might be able to help me out without taking up too much of your time.
 
I have a black garment, composed of 80% Nylon, 20% Spandex, and I would very much like to turn it white, bright yellow, or bright pink. White is preferable, which is more of a bleaching process I would imagine. But any of these will do.
 
Is there a method you can suggest that will reliably accomplish turning the black into one of these colors without damaging the fabric?

This is difficult problem, one that cannot always be solved. The spandex that is blended with the nylon in your garment causes a lot of trouble, as a spandex/nylon blend is far more difficult to decolorize or dye than plain 100% nylon would be. It is likely that it will be impossible to do what you want to do.

As you have suspected, it's almost never possible to remove all of the color from a piece of dyed fabric; the very best you can expect it to obtain a tan or beige color, and sometimes you get quite unexpected colors, such as orange or dull green. Unfortunately, you can never have any idea in advance of whether ANY of the color will be removable. Some dyes can be discharged, but others are completely resistant to discharging. Some dyes are so resistant to discharging that they can be reduced to shreds by the discharging agent and still retain their color.

The first thing to know is that synthetic fibers, such as nylon and spandex, are badly damaged by exposure to household chlorine bleach, which is based on hypochlorite. Nylon pretty much dissolves in hypochlorite, and spandex develops holes and weak spots. Never use hypochlorite bleach on any garment containing nylon or spandex. Only 100% cotton, linen, hemp, or other plant-based natural fibers can be decolorized with hypochlorite bleach.

However, there are alternatives that work in a completely different way. While hypochlorite bleach is an oxidizer, which works by breaking up the dye molecules, the other chemicals that can be used to remove dye are all reducing type dye discharge agents. Their dye removal activity depends on their ability to chemically reduce the double bonds found in colored substances. I have written an article about the different chemicals that can be used to remove dye: see "What chemicals can be used to remove dye?", and scroll down to the section on reductive discharges.

The problem with the reductive discharge chemicals is that they all require heat to work well. This is a big problem for your project! Spandex is extremely sensitive to heat; in fact, I would advise you strongly to follow the care instructions on the label, which almost certainly indicate that the garment should be kept at or below 105°F (41°C). If you use higher temperatures, you are likely to find that the shape of your garment is distorted. Spandex can be dyed industrially at temperatures up to 140°F (the temperature of hot tap water), but that is before it has been manufactured to its final shape. (See "How to Dye Spandex".)

You should experiment with removing the color from your garment only if you will not mind very much if the garment is destroyed by your efforts. If you use a color remover without heat, most of the color will probably remain, though there's a chance that you will be very lucky and find that the dye in your garment is unusually easy to discharge. If you use the recommended amount of heat for the discharge chemical, your garment is likely to be damaged. Be very careful not to twist or stretch your spandex-containing garment while you are manipulating it.

The easiest to find of the discharge chemicals is Rit Color Remover; there are similar products under other brand names, such as Tintex Color Remover. Like all reductive discharge chemicals, Rit Color Remover requires heat to work. The easiest way to use it is in hot tap water in a washing machine, while the most effective method is to cook the garment in the color remover in a pot on the stovetop, bringing the temperature up to a simmer. Obviously, the stovetop method is right out, for a spandex blend. You might try the color remover in warm water in a plastic dishpan or bucket, being very careful not to twist or stretch the garment as you stir it. If you do not stir frequently, the color removal will be uneven, producing a somewhat tie-dyed effect, but if you stir vigorously, the garment is more likely to be damaged.

An alternative chemical that is not difficult to find is Jacquard Color Remover. It contains an entirely different chemical than Rit Color Remover, and thus it may perform differently at the low temperatures you will be forced to use. The best instructions for thiourea dioxide, the main ingredient in Jacquard Color Remover, say to heat the garment to 180°F (82°C), but Jacquard's instructions imply that it can be used with more limited success at much lower temperatures. There is no guarantee that it will have any effect at all on the color of your garment, however, especially at temperatures below 180°F.

If you do manage to remove most of the color from your garment with a sulfur-based discharge agent, you will then need to dye it in order to cover up the beige color that is a likely result. Nylon can be dyed with a type of dye called acid dyes. Unfortunately, acid dyes require heat to attach well, so you once more run into the problem of being unable to follow the most effective recipe because of the heat-sensitivity of your spandex. You can try dyeing your nylon with a bright pink acid dye in warm water. A very brilliant true fluorescent pink acid dye is Rhodamine B, sold by PRO Chemical & Dye as 370 Rhodamine Red B and by Jacquard Products as 620 Hot Fuchsia. This dye, like all non-food-tested dyes, should never be used in any cooking pot that you intend to use again for food. There is some suspicion of possible carcinogenicity, so you must use only dyepots that will not be used with food, and wear gloves and take appropriate safety precautions.

It's likely that you will do better to buy a new garment in a color that you find more acceptable than the black one you already own. You may also wish to consider decorating the garment with an opaque metallic or pearlescent color of fabric paint that will show against the black material.


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