Name: Andrea

Message: Hi, my name is Andrea!  I’m an 8th grade student who is conducting a science fair project to determine if the fabric content of a tee shirt affects the brightness and colorfastness when tie dyeing.  I found your website in my research and it is a tremendous help.  I would like to use you as a subject expert, and am hoping that you can answer a few quick questions.

1. I am going to compare the results of tie dying three blends of T-shirt fabric with the same dye -- 50% cotton/50% polyester, 90% cotton/10% polyester, and 100% cotton.  Would all-purpose or direct dye be a better choice?
2. Do 100% cotton or fabric blends generally absorb more color? 
3. And do some colors of dye last longer and stay brighter than others?

Direct dye is a better choice than all-purpose dye, because you cannot identify what is in any all-purpose dye. In a scientific presentation, you want to be able to specify what chemicals you used, but it is impossible to find out what specific dyes have been used in any packet of all-purpose dye. I think it looks a lot better to be able to say that you used "Colour Index Reactive Red 2" or "Colour Index Direct Blue 98", since these are generic names that refer to specific chemicals, instead of just saying "Rit® All-Purpose Tint And Dye #33 Aubergine", which might contain an entirely different set of chemicals by this time next year, for all we know. We never know what is in the dye mixtures made by the Rit® dye company (Phoenix Brands), but we do know what dye chemicals are in specific unmixed single-hue reactive or direct dyes, if you purchase them from a good dye supplier such as PRO Chemical & Dye.

You will find that no commonly used dye that works on cotton will work on polyester; instead, it will just wash out of the polyester fiber, leaving it undyed. A cotton/polyester blend will dye more intensely than 100% polyester, if you use a cotton dye such as reactive dye or direct dye (or all purpose dye), and 100% cotton will dye more intensely still.

If you find a tie-dye kit at your local crafts store, you can use that and know exactly what dyes you have, unless you choose a Rit brand tie-dye kit. Tie-dye kits made by Dritz, Tulip, Dylon, Rainbow Rock, or Jacquard Products all use the same kinds of fiber reactive dye. If they contain turquoise, yellow, and fuchsia dye, then you know that the turquoise is Colour Index Reactive Blue 140, the fuchsia is Colour Index Reactive Red 11, and the yellow dye is Colour Index Reactive Yellow 86. Otherwise, I recommend that you mail-order dyes from PRO Chemical & Dye according to the list of unmixed single hue Diazol Direct dyes on my page About Direct Dyes, since these direct dyes have known generic names and identities. If you mail-order reactive dyes, there are more sources for Procion MX type dyes with known generic names, which you can see listed on my chart of Which Procion MX Dyes are Pure rather than Mixed?. 

All of these dyes work well on cotton and poorly on polyester. In order to do well at dyeing polyester, you need to use a completely different type of dye which is called disperse dye.

It is important, I think, to use a single-hue mixed dye for this sort of experiment. It's too confusing when one dye in a premixed color works better than another, so, for example, a green dye mixture may shift to be more turquoise or more yellow on different fibers.

You are welcome to list me as your subject expert. If you need any information about me to use, see the August 28, 2007 entry in this blog. If you send further questions about your project, I will attempt to answer them.


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