Is it possible to skip a step and mix all-purpose dye and dye fixative into the dye bath at the same time?

Name: Rochelle

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Rit Dye Fixative

Rit Dye Fixative solves the problem of fading and bleeding when you dye clothes with all-purpose dye. Like all dye fixatives, it cannot be used for tie-dyed clothing. Use one-half bottle per pound of fabric.

Country or region: NY, US

Message: In your blog, you write that Rit Fixative should be used in a separate dye bath after dyeing, because the OP had already dyed her fabric. Is it possible to skip a step and pour the fixative into the dye bath, thus draining excess dye from the fabric only once?

It's not a good idea, for more than one reason. The first reason is that, if you're planning ahead this much when dyeing, you probably should not even be using an all-purpose dye, such as Rit, at all. The only time it's really a good idea to use all-purpose dye is when you're dyeing a garment that contains a blend of both nylon (or wool) and cotton (or rayon). If you are dyeing only one fiber, it's much better to use a higher-quality, less-expensive dye that doesn't require the commercial dye fixative. Cotton and rayon should be dyed with fiber-reactive dyes; wool and nylon should be dyed with higher quality, more washfast types of acid dye. (Incidentally, higher-quality dyes are nearly always much less expensive, per pound of fabric dyed, than Rit all-purpose dyes.) Clothes that contain both nylon and cotton are not all that common. Cotton-polyester blends are very common, of course, but Rit dye doesn't work on polyester at all, so it's no use for those blends.

The time to use Rit Dye Fixative, or any other cationic dye fixative such as Retayne or Dharma Dye Fixative, is when you don't have a choice of dye type. When you have purchased commercially-dyed fabric or clothing, and found that it's not as washfast as you need it to be, that's the best time to use Retayne. If you've already dyed something with Rit because you have only just now learned that you should have gotten a better dye, then you should use Retayne. If you're about to dye cotton, and haven't started the dyeing process yet, though, you still have time to choose a better dye that will last longer than any of these dye fixatives can, and without the side effects. Rit Dye Fixative and similar products tend to make dye fade more rapidly when exposed to sunlight.

Now, suppose that you have a good reason for using all-purpose dye, such as dyeing a washable garment that contains both nylon and cotton. I still wouldn't want to mix the cationic dye fixative directly into the dyebath. Here's why:

The Rit dye particles (a mixture of acid leveling dye and direct dye) are all negatively charged. So is your fabric. The way the cationic dye fixatives work is that they are positively charged. They associate with both the negatively charged dye molecules and the negatively-charged fiber molecules, more-or-less gluing them together.

When you dye with Rit dye, a large proportion of the dye molecules will not go onto the fabric, but instead stay in the water. This, by the way, is the nature of all cotton dyes, both the direct type and the fiber reactive type. Acid dyes tend to exhaust onto a wool fabric, but when you're dyeing cotton, a large portion of the dye remains in the water.

If you add the positively-charged dye fixative directly to the bath full of excess dye, it will stick directly to the dye molecules, as they float around. This means much of the dye fixer will be wasted, so you'll need to use more. It also means that some of the dye-fixer complexes that are floating around will stick to the fiber, when they might not otherwise have done so; what worries me about this is the idea that they will stick primarily to the outer surfaces of the fibers, instead of penetrating within before sticking. Dyeing the outer surfaces of the fibers in a fabric is called ring-dyeing. It seems to me that it's better to get the dye inside the fiber, and then fix only those dye particles into the fiber, rather than encouraging additional dye to fix onto the outside, where it will tend to wear off, or even crock off (rub off when dry), much more quickly. Admittedly, however, I haven't tested this hypothesis. Most of the time, it's so much easier to just use good permanent types of dye to begin with, and forget about all-purpose dye or the commercial fixatives needed to keep it from bleeding so badly in the laundry.

In addition, remember that all-purpose dye contains a lot of dye that needs to be washed down the drain, since it's a mixture of dye types. The direct dye in the mix that is intended to dye the cotton will not work on nylon or wool, and must be rinsed off of it; the acid dye that is intended to work on nylon or wool should be rinsed off of cotton. When you add the cationic dye fixative, it will tend to make all of these dyes stick to everything. The direct dye will be sticking to the wool, and the acid dye to the cotton. As it does so, however, it won't be sticking as well as it might if it also had an innate affinity for the fiber. Better to get the dye to stick as well as it can by normal dyeing mechanisms, washing away the excess, and then use the fixative to improve matters from there.

Interestingly, the dye fixatives themselves vary widely in how much they cost to use. The cheapest one, Retayne, costs less than a tenth as much to use as the most expensive one, Rit Dye Fixative! Check out this Dye Forum post on a comparison of dye fixative costs. It's cheaper still to use a good fiber reactive dye and skip the use of the dye fixative altogether, though.

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Posted: Tuesday - May 22, 2012 at 09:47 AM

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Is it possible to skip a step and mix all-purpose dye and dye fixative into the dye bath at the same time?

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