Category Archives: dyeing synthetic fibers

looking for a light-fast dye or pigment with peak absorption centered between about 570-590 nm

Dear Paula,

I came across your website on dyes, it’s great! Currently, I’m experimenting with an idea to understand how insects see color in plants and how it may relate to a decreased use of pesticides. Something that we all may benefit from. In this, I’m looking at a light-fast dye or pigment with peak absorption centered between about 570-590 nm. The narrower the absorption band the better, and the lower the fluorescence quantum yield the better (for a controlled experiment on absorption).

The material substrate is polyurethane or other plastics. Would you know some dyes that would fit the mold?

Thank you!


Hi Keenan,

You want a dye that absorbs in the orange range, which means you want a dye that looks blue. To help with visualizing this, let’s look at a graph I happen to have handy, which shows the absorption spectra of a number of dichlorotriazine dyes that are popularly used for hand dyeing:

absorption spectra of a number of dichlorotriazine dyes that are popularly used for hand dyeing CLICK TO SEE FULL SIZE

(Image provided by Olli Niemitalo.)

The closest of this range (which is not suitable for your substrate; I’m using it only because it is handy) is Procion Blue MX-7RX, which is Colour Index Reactive Blue 161. Its peak is not as sharp as you’d like, anyway, as it absorbs pretty significantly from 530 to 640 nm. Procion Blue MX-7RX is notable for a deep violet-blue color. It is also noted for being quite poorly lightfast when used on cotton, though its lightfastness is significantly greater when it is used with an acid dye recipe on silk.

Dyes that have narrow absorption ranges are unusually clear and bright in color. Wider absorption ranges result in duller colors. A dye that has a very narrow absorption range cannot be used to produce a dark color, no matter how high a concentration of it is used, because it allows most colors of wavelengths to be passed freely. Your desired dye will be a very bright, clear blue, on the violet side of blue, since it will not absorb any wavelengths in either end of the spectrum. You do not want a dye whose color is described as a navy blue, because navy blue dyes always absorb over a wide range of the visible spectrum. You may want to look for a blue dye whose name includes the words “brilliant” or “bright”. There are many dyes that are of a medium royal blue color or of a cyan color, or of a reddish violet, but violet-blue dyes are far rarer. Of course, it is no use to look at dyes that are composed of mixtures of other dyes, as these will always tend to absorb a winder spectrum.

The one person I know who has made a great study of blue dyes is Dr. Steve Mihok, who looked at dyes that attract tsetse flies when used in fly traps. You can see his descriptions of many blue dyes using the Internet Archive (his original site appears to have been taken over by spam and no longer contains useful information). See his page “Blue Dyes” at the Internet Archive, captured in January of 2012.

Mihok concentrated on metal phthalocyanine dyes, which tend to absorb in a turquoise-blue range, I’d say around 600 to 700 nm. My one example dye which absorbs near your target, Colour Index Reactive Blue 161, has as a chromophore a triphenodioxazine structure, I believe. It would make sense to look for a dye with this same chromophore. Following is an image of Direct Blue 106, as an example of the triphenodioxazine structure:

an image of Direct Blue 106, as an example of the triphenodioxazine structure

Unfortunately, the large size of this chromophore may make it unsuitable for use in plastics. Disperse dyes are typically relatively small molecules. The 2003 book “Industrial Dyes: Chemistry, Properties, Applications”, edited by Klaus Hunger, says, “Like phthalocyanine dyes, triphenodioxazine dyes are large molecules, and therefore their use is restricted to coloring the more open-structured substrates such as paper and cotton.” (page 112) I suspect that this leaves you having to find an antraquinone dye. Anthraquinone dyes include many popular blue dyes, such as Procion Blue MX-R (reactive blue 4) and Remazol Brilliant Blue R (reactive blue 19), and many violet dyes, as well. This is disperse blue 3, an example of an anthraquinone dye:

disperse blue 3, an example of an anthraquinone dye

It is important to consider what class of dye you need. Different materials require different dyes; for example, a dye that works on wool is unlikely to work on cotton, and dyes that work on either cotton or wool will not work on polyester, but wool dyes will work on nylon. You say that you want to color polyurethane or other plastics. Polyurethane is quite different from PET plastic, in its dyeing properties, which in turn is quite different from nylon plastic. Although no acid dyes work on polyester (which includes PET), acid dyes can be used to dye polyurethane, though with varying degrees of washfastness. The most washfast acid dyes to use on polyurethane would be metal complex acid dyes. Disperse dye, which is used on most synthetic fibers and is the only option for dyeing polyester, can be used to dye polyurethane, but the washfastness is poor, and the heat required may damage the polyurethane.

It is probably best to dye polyurethane in liquid form before fabricating it into objects. Solution-dyed plastics tend to be more resistant to both light-faging and wash-fading than fabrics dyed after manufacture. This is the explanation of why, for example, Sunbrella brand acrylic fabric is so resistant to fading that it can be used in outdoor furniture that retains its color even after extensive exposure to run and rain. I imagine that you would use a solvent dye for coloring the liquid plastic before using it in manufacturing. Solvent dyes are not soluble in water, but are soluble in organic solvents. Many disperse dyes, which are used with special carrier chemicals to dye polyester fiber after manufacture, are actually identical to solvent dyes.

To color the widest range of already-manufactured plastics, I’d suggest you concentrate on disperse dyes, especially since washfastness is not as much of an issue for you. They will work on nylon, polyester, and polyurethane. When dyeing polyester it is generally necessary to use boiling temperatures and an additional carrier chemical; when dyeing other plastics, the carrier chemical should be omitted, and lower temperatures may be adequate, though the water must still be very hot, at least abot 60 degrees C. Nylon can be dyed at lower temperatures than polyester, and I think the same is probably true of polyurethane as well.

Sourcing your blue dye is an issue. You will note that many textile dyes are sold in the form of in-house mixtures, whose constituents are not made public. Dyes obtained from chemical suppliers tend to be much more expensive per gram, perhaps with greater purity, prohibitive for dyeing large quantities. Textile dye suppliers such as PRO Chemical & Dye and Aljo Manufacturing sell dyes in useful quantities for hand dyers, often at much better prices, but in some cases the generic identity of dyes is not made clear, and many dyes are sold as mixtures in order to produce specific colors. I have listed a number of disperse dyes that are used for hand dyeing in a large chart on my page, “About Disperse Dyes”, at , including disperse blue 3, which is described a sky blue and is sold by Aljo, and disperse blue 56, sold by ProChem, which is described as royal blue; disperse blue 60 is described as turquoise, so its absorbance is probably at a greater wavelength than you want, and disperse blue 281 is described as navy blue, which would have far too wide an absorption band to suit you.
Sigma Aldritch sells Disperse blues 1, 3, 14, 27, 35, 56, 60, and 124. All of the ones whose structures are indicated on their web site are anthraquinone type dyes. I suggest that you contact Sigma Aldritch and ask about the absorption spectra of all of these dyes.

I’ve been discussing only dyes, but you did mention pigments as an alternative. Pigments differ in that they do not bond directly to a substance, but instead are glued to it by some sort of binder, or they can be incorporated directly into some materials. Pigment dyes are pigments whose binder systems allow them to be applied in much the same way as dyes. Unless a pigment is sold with a Colour Index number, it probably consists of a mixture of more than one colored substance. The only pigments I would recommend you look at would be those sold by a chemical supplier such as Sigma Aldrich.

I am very interested in your project and would appreciate it if you would let me know more about it in the future.

For more information, see the following pages:

About Disperse Dyes

Dyeing Polyester with Disperse Dyes

What to Use to Dye White Polyurethane Foam, December 19, 2007

Steve Mihok’s Blue Dyes, captured by the Internet Archive on January 24, 2012

Sigma Aldrich

Lightfastness of Different Types of Dyes

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Is there a dye that can colour PET (polyethylene terephthalate)?

Name: Kathy
Country or region: Australia
Message: Hi Paula,
I’m wondering if there’s a dye that can colour PET (polyethylene terephthalate)?
Thanks for your help


iDye Poly

iDye Poly dyes polyester and other synthetic fabrics. 16 colors including black!

buy from

Yes. PET is a common form of polyester, which can be dyed with a class of dyes known as disperse dye. Disperse dye is only slightly soluble in water, and works best on polyester when used with a carrier chemical. Without a carrier chemical, you can achieve only paler shades on polyester.

Dyes that are made for use on cotton or wool will not work on PET and other forms of polyester.

For more information, see my page, “Dyeing Polyester with Disperse Dyes“.

In Australia, you can buy disperse dyes under the brand name of Polysol, from Batik Oetoro, or Polytex, from Kraftkolour, or you can buy Jacquard brand iDye Poly (not iDye without the Poly, which is for natural fibers) from companies that import Jacquard products. For contact information for dye suppliers in your area, see my page, “Sources for Dyeing Supplies Around the World”.

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For polyester, do you know anything about Rit DyeMore (for synthetics)?

Name: Danielle
Location: California
Message: For polyester, do you know anything about Rit DyeMore (for synthetics)?


Rit DyeMore
Liquid Dye
for Synthetics

Dyes polyester and cotton-poly blends, acrylic, acetate and nylon by stove top dye method.

Buy from


iDye Poly

iDye Poly dyes polyester and other synthetic fabrics. 16 colors including black!

buy from

Rit DyeMore, introduced only a year ago, contains a type of dye called disperse dye, which can be used to dye synthetic fibers including polyester, nylon, and acrylic. Disperse dye is the only type of dye that works on polyester. Rit All-Purpose dye cannot be used to dye polyester.

Alternative brands of disperse dyes produced for home use include two lines sold by PRO Chemical & Dye, PROSperse Disperse Dyes and PRO Transperse Transfer printing dyes, and iDye Poly, which is made by Jacquard Products. iDye Poly is available in sixteen different colors, and PROsperse in twelve. You can order PROSPerse dyes directly from PRO Chemical & Dye, while iDye Poly is sold by many suppliers of art materials, including Dharma Trading Company, and, if you’re lucky, some local fabric and art supply stores. Another source of disperse dye is Aljo Manufacturing in New York, which sells two different lines of disperse dyes, Aljo Acetate-Nylon dyes and Aljo Polyester disperse dyes. The Aljo Polyester disperse dyes are available in twenty-two colors. (For contact information for these suppliers, see “Sources for Dyeing Supplies Around the World”.)

It is impossible to tell which specific dyes are contained in the different colors of Rit DyeMore, which is not surprising because this is nearly always the case for dyes that are sold under the Rit name. (The only exception is the colorless ultraviolet-blocking Sun Guard dye.) They are probably among the lower-energy type of disperse dye, which require less heat or assisting carrier molecules, but which transfer more quickly to polyester from a dyebath than higher-energy disperse dyes.

I am not sure, but it seems possible that Rit DyeMore formulas may also contain direct dyes, in addition to the disperse dyes for polyester. Direct dye is for dyeing cotton, rayon, and silk. The Rit dye company appears to advise that DyeMore will also dye cotton or rayon, which we know that disperse dye is not good for, though they do say DyeMore will not dye wool. Disperse dye can stain cotton, but does not bond to it well enough to make it suitable for use as a cotton dye.

It’s important to note that there is no true black in the Rit DyeMore line of dyes. The darkest color in the range is “graphite”, which is a dark gray. For a true black on polyester, you should consider one of the other brands of disperse dye.

The colors available in the Rit DyeMore line are named as follows: Daffodil Yellow, Sand Stone (tan), Apricot Orange, Racing Red, Super Pink, Royal Purple, Sapphire Blue, Kentucky Sky, Peacock Green, Frost Gray, and Graphite. If the colors available in the DyeMore line do not match what you need for a specific project, they are not the best choice for mixing different colors. The yellow has too much orange in it to be an ideal mixing primary, and there is no pure cyan. I would recommend one of the other brands of disperse dye for color mixing.

Polyester requires high heat to accept disperse dyes. There are two ways you can supply this: either by boiling the fabric in a dyebath, which is a large pot of water with the dye and auxiliary chemicals, or using the dye to make designs on paper, which can then be transferred by ironing them on. Disperse dyes that have been selected to be suitable for the latter method are often labeled as “transfer dyes”. Rit DyeMore is intended only for use in the dyebath method.

Dyeing polyester with Rit DyeMore requires heating the fabric in the dye on the stovetop at a minimum of 180°F (82°C), preferably closer to boiling (212°F or 100°C), for at least thirty minutes. (Instructions are available at the Rit website). Other materials such as acetate and acrylic will generally take this sort of dye with less heating. The cooking pot used must be large enough for the material to move quite freely in the water, unless you are interested in a non-uniform “crumple dye” effect. As with all textile dyes that are not originally sold as food coloring, the Rit DyeMore dyes should not be used in cookware that you plan to reuse for food preparation, as some of the dyes or auxiliary chemicals may be toxic or carcinogenic when eaten. Aluminum pots are not recommended because the salt in the DyeMore mixture will tend to cause corrosion to the aluminum, but if you have an inexpensive aluminum pot that you don’t want to save for kitchen use, it’s worth trying. Stainless steel pots and enameled pots are the best choice; enameled pots are less expensive than stainless steel, but if they become chipped inside can contaminate the dyes with iron, resulting in dull colors.

One bottle of Rit DyeMore should be sufficient to dye one to two pounds of fabric, in three gallons of water in a sixteen-quart pot. Using a smaller cooking pot will result in less uniform colors. When dyeing a dark color, double the amount of dye used.

Comparison of costs: as is typical of Rit dyes, the DyeMore line is quite dilute, compared to other dyes, which makes it more expensive than would appear at first glance; the bottle contains more water than anything else, just as Rit Powder Dye is mostly salt and detergent. One seven-ounce bottle of Rit DyeMore costs $5, or about nine dollars on Amazon, and will dye one to two pounds of fabric. One small fourteen-gram packet of Jacquard iDye Poly costs $3.79 and will dye two to three pounds of fabric. PROsperse dye is more concentrated; while four grams of it is sufficient for a medium shade, and eight grams for a dark shade, fifteen grams costs only $2.49 (plus shipping) on the PRO Chemical & Dye website, and bulk quantities are available at a steep discount (e.g., four ounces, or 120 grams, for fourteen dollars).

Rit DyeMore, like Jacquard iDye Poly, is convenient for the beginning dyer who does not want to measure out salt or vinegar or other auxiliary chemicals. Nothing needs to be added to the DyeMore recipe, except for water and fabric. The formulation probably contains unspecified auxiliary chemicals known as dye carriers, which help polyester to accept dye without requiring temperatures well above boiling. iDye Poly contains a dye carrier chemical in a separate packet within the iDye Poly package; it should be omitted when dyeing synthetics other than polyester, such as acetate or acrylic, as it is not needed for them. Some dye carrier chemicals are rather toxic and smelly, and all should be used only with good ventilation. Be sure to keep at least a window open when dyeing polyester; better to have an outward-facing fan in one window, and an inward-facing fan in another. The Rit DyeMore MSDS [PDF] is uninformative, as it is the same one supplied for Rit All-Purpose Liquid dye, which contains entirely different dye chemicals.

It is a fine thing that Rit has introduced polyester dyes, because this may make them more accessible to more people, but the requirement to obtain a very large cooking pot for use with dyes, and not with food, makes immersion dyeing polyester an expensive project for the beginning dyer. Dyeing cotton with fiber reactive dyes requires much less investment, since they can be used at room temperature with plastic containers. Other brands of disperse dye cost significantly less than DyeMore per pound of fabric, and are available in colors that have been selected to be better for color mixing.

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