Monthly Archives: August 2014

Will hair dye developer make it possible to dye polyester with Rit dye?

Name: Irene
Country or region: United Kingdom
Message: Hello, I researched using rit dyes for dying polyester and it says that one thing required to add to dye bath is dye developer. I googled this and nothing comes up, except for hair products. Do you know if this is commonly used for polyester dying and where it can be found? thanks

There is nothing that will work to fix Rit dye on polyester. Rit All-Purpose Dye simply cannot be used to dye polyester! It can be used to dye cotton, silk, rayon, and nylon, but never polyester, no matter what chemical, fixative, or dye developer you try to add. Hair dyeing products will not help in dyeing polyester, regardless of what type of dye you use.

Polyester cannot be dyed with any dye that works on natural fibers. If a dye can be used to dye cotton, silk, or wool, then it will not work for polyester. The only type of dye that will work on polyester is a class of dyes that is named “disperse dye”. (See my page, Dyeing Polyester with Disperse Dyes.) Sometimes you will see disperse dye being sold under the name “transfer dye”, because disperse dyes can be used to make designs on paper that are then transferred to polyester by pressing with a hot iron.

To find a company that will sell you disperse dye in the UK, take a look at my page, “Sources for Dyeing Supplies Around the World“. You can order disperse dyes online in the UK from George Weil, Kemtex Educational Supplies, Omega Dyes, and Rainbow Silks.

A dye carrier that is sold by some dye suppliers for use with disperse dyes can be used to make the colors of disperse dye more intense. This is available under different names, but only from textile dye suppliers. IDye Poly, a brand of disperse dye marketed in many different countries by Jacquard Products, comes with a dye carrier included in a separate packet within the package of dye; PRO Chemical & Dye, a dye supplier in the US, sells a chemical called Dye Carrier NSC for this purpose.

Dyeing polyester requires extensive application of high heat. In addition to the special polyester dye, if you will be immersion dyeing fabric or clothing, you will also need a large non-reactive cooking pot, one which you plan never to use again for food. The pot must be large enough for the material you’re dyeing to move about freely in the boiling water. By non-reactive”, I mean a stainless steel pot, or an enamel pot with no chips in the inner lining. Do not buy an aluminum or cast iron pot for dyeing polyester.

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Do you know where I could purchase a liquid version of sulphur dioxide?

Name: Lisa
Country or region: USA
Message: Hello,

Do you know where I could purchase a liquid version of sulphur dioxide? I’m looking for a color remover that is safe on skin and hair, and also will not change the color of skin or hair. According to your list it seems like sulphur dioxide is what I’m looking for. I read that it’s used as a preservative. Please feel free to provide any other suggestions if you know of anything better than sulphur dioxide. Thanks

Sulfur dioxide, which exists in the form of a gas, is not a particularly safe chemical. It is not safer than the color removers listed on my page, “What chemicals can be used to remove dye?“. In fact, most of the chemicals listed there react to produce sulfur dioxide. They are much safer than the medieval process of burning sulfur to fumigate fabric with sulfur dioxide fumes; their greater safety is due to their making it possible to lessen the total exposure to sulfur dioxide. The biggest problem with any chemical that produces sulfur dioxide comes from breathing its fumes, which can cause asthma, and can, if the amounts are large enough, damage the lungs even of people who previously had never shown any tendency toward asthma.

The way sulfur dioxide and other sulfur-based color removers work is by chemically reducing the double bonds that give dyes and pigments their colors. After a double bond in the dye molecule has been reduced to a single bond, the dye molecule no longer provides color, although it is still present. Some colored substances are very susceptible to reducing agents, while others are resistant and do not show a change when treated with reducing agents. Some change from one color to a surprisingly different color. When removing color from fabric, whether you are using a reducing agent or an oxidative bleach, often you will see “off” colors appear. For example, when removing a dark color, you may end up with tan or orange instead of an absence of color.

When dye is applied to hair, the naturally occurring pigment in the hair is frequently intentionally bleached out as part of the process, both to make the added color stand out more, and to make the hair strand itself more amenable to absorbing the dye. As a result, it’s not unlikely that removing hair dye will result in an unexpected color even if the color removing product works perfectly. In addition, not all dye colors are affected equally by any given color removing chemical.

There is a commercial product, called Color Oops Hair Color Remover, which is based on the same hydrosulfite that is the active ingredient in Rit Color Remover. Rit Color Remover is an excellent product for removing dye from fabric or yarn, in fact higher in quality than Rit Dyes. I expect that the formulation of Color Oops is much kinder to the skin and hair. Although I have never used this product and cannot evaluate how effective it is, it seems to me that this category of product would be a better choice when there may be skin or hair exposure than the textile-oriented color removers, since it is marketed for the express purpose of applying to the hair. One caveat: sodium hydrosulfite tends to break down when dissolved in water, so you should expect any liquid hydrosulfite product to have a short shelf life; be sure to buy it fresh each time you need it, rather than using an old bottle you’ve had for a while. Dry powdered hydrosulfite will last much longer.

There is some useful information in the customer reviews of Color Oops at

Other products promoted for the same purpose include VANISH Color Corrector, L’Oreal ColorZap Haircolor Remover, and One ‘n Only Colorfix, among others. It is harder to find out their active ingredients than it was for Color Oops, so I can only assume that they are similar in composition and safety.

VANISH Color Corrector is claimed to “gently reduces the size of the artificial color molecules, allowing the color to be washed away, with no damage to the hair”. While oxidative discharge agents, such as chlorine bleach, which is based on sodium hypochlorite, make color molecules smaller by attacking them and breaking them up, this seems an unlikely mode of action for a product that is claimed to be safe for the skin and hair. Anything that breaks apart dye molecules will probably break apart the proteins in skin and hair, as well. The product probably contains a reducing agent similar to that in Color Oops, which does not change the size of the color molecules, but instead removes their double bonds.

L’Oreal ColorZap Haircolor Remover is described as follows: “ColorZap will not restore hair to its original, natural color. It removes the tint revealing the underlying base from which the natural color has been removed in the haircoloring process.” Although it is supposed to leave the underlying natural color unaffected, if any of it still remains, a customer review claims that it does lighten the original color of the hair, more than Color Oops.

(Incidentally, you see both spellings, “sulfur” and “sulphur”, in print. Which is correct? It depends on what publication you are writing for. “Sulphur” is the British spelling, while “sulfur” is used in American English and is the spelling recommended by IUPAC, the International Union of Pure and Applied Chemistry.)

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color-changing yarn

LAB wrote:
I recently bought some interesting yarn – it’s a radically different color depending on what sort of light it’s exposed to. I’ve seen this sort of yarn a couple of times from different dyers – it’s fascinating. I’d love to know how it’s done. Would you happen to know?

It’s from the Mystical Moose series, on this site:

This is wonderful stuff! It’s like the gemstone alexandrite, which is green in daylight, but changes to red under incandescant light. The way it works is that the coloring in an alexandrite stone absorbs light in the yellow range of the color spectrum–the color spectrum is the range of colors you see in a rainbow–while allowing you to see light in both the green part of the spectrum and the red part of the spectrum. If the original light that is shone on it contains more red light, like incandescent light bulbs or a candle flame, that that is the light that you see, whereas if the original light contains more green and blue light, such as sunlight or a halogen lightbulb, that is the color you see. The color in alexandrite is provided by small amounts of vanadium or chromium in the gemstone.

You can’t get this effect simply by dyeing with two different dyes, each of which reflects light in one of the two colors you want to see, because dyes, like paints, work in a subtractive way. If you apply a red dye to fabric, it works by absorbing the green light, so all you see is red, whereas if you apply a green dye, it works by absorbing the red light, so all you see is green. If you apply two different dyes, a green one which absorbs red light, and a red one which absorbs green light, the two colors are both subtracted from the light you see, which is why dyeing the same piece with both red and green dye results in a dark brown color.

The only way you can produce the different colors under different lighting is to have both extremes of color reflecting from the same dye, and then compare the effects of a warmer light against those of a cooler light. It’s simply a question of choosing a particular dye that absorbs in the correct parts of the color spectrum. There aren’t many dyes in common use that show this effect so strongly, and I’ve never seen them marketed for this property. Often the property of showing markedly different colors under different lights is considered a defect in a dye, because people want their ordinary clothes to be a predictable color. If you put on a red shirt under an incandescent light at home, you’re not expecting it to turn brown under the cooler fluorescent lights at work. When the special color property of the dye is remarked on at the time of sale, however, what is sometimes a defect instead becomes very desirable. It becomes something you can play with.

I have observed this effect in a subtler form myself. I purchased some of a rather expensive Procion MX dye, red MX-G, also known as Colour Index Red 5, from George Weil in the UK. It is much closer to a true red than our usual red mixing primaries, which are red MX-5B (magenta) and red MX-8B (fuchsia), both of which reflect a large amount of blue light as well as red light. I was trying to decide if it was really a true red, or tilted slightly toward the orange or the blue side of red. It was impossible to decide. When I looked at fabric I had dyed with red MX-G, it seemed to be slightly orangish indoors, but slightly blue under the light of the sky. It was only a mild effect, though, not nearly as extreme as in the Mystical Moose series series of yarn. Red MX-G is not a popular Procion dye, by the way, because it is quite expensive, and yet a very similar color can be obtained much more economically by mixing red MX-5B (magenta) with orange MX-2R (strong orange).

Now obviously all colors are somewhat affected by the color of the light you shine upon them. A dye or pigment has its color because it reflects only a limited portion of the visible spectrum of light, but if the light source contains a different balance of colors, the dye or pigment can’t show you any more light than it receives. Mostly our brains somehow manage to correct for the different colors of light, so that we usually notice the changes only in photography. Why haven’t we noticed the difference between the blue/red balance of a pure fuchsia dye under warm lights versus cool lights? It reflects both blue and red light, after all. The difference is there, but it is far less visible than that of the dramatic variations in the Mystical Moose series of dyed yarn.

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