Name: Emma

Message: I like your website a lot! It has helped me with my science project. See I am 11 years old and I am doing a science project about dying.  am seeing which dye works best out of 3 dyes; Rit,Rainbow Rock, and Dlyon. I am following the package instructions of each dye. On Rit, it says to add laundry detergent to the dye bath. I was wondering why it says to add that and how it helps.

Most dyes sold by the Rit dye company are a type of dye called "all-purpose" dye. It is a mixture of two different types of hot water dye: "direct" dye, which works on cotton, rayon, and silk, and "acid" dye, which works on wool, nylon, and silk. The main purpose of the laundry detergent is probably to help the dye penetrate the fabric. It does this by reducing surface tension. Surface tension is a property of water that makes water molecules stick together. Reducing surface tension helps many chemicals to dissolve more easily in water.

Another possible use of laundry detergent in dyeing would be to increase the pH of the water, because many laundry detergents include a chemical called soda ash. Direct dye (one part of the all-purpose dye mixture) does not need soda ash to work, though. Dyes that need soda ash work better when you use pure soda ash, instead of laundry detergent, anyway.

What kind of fabric are you using for your tests? 100% cotton is usually the best choice. Do not try to dye polyester fabric. None of the dyes you have chosen will work on polyester.

Direct dye does not need chemicals other than salt to work, but it needs very hot water to make its best attachment to fabric. In contrast, fiber reactive dye requires soda ash to work well, but it can be used in cool water (70°F or higher), and it attaches much more permanently. The colors produced by fiber reactive dyes are better, and they are easier to apply since they do not need to be heated with the fabric.

Dylon is a dye company that sells many different types of dye. You will need to specify which of the Dylon types of dye you are using. The easiest to find in the US is Dylon Permanent dye. It is a type of fiber reactive dye. However, Dylon also makes a dye called Dylon Multi Purpose dye, which is, like Rit dye, an all-purpose dye, which is a mixture of direct dye and acid dye.

Dylon Permanent dye contains fiber reactive dyes that are known as Drimerene K dyes. There is another kind of Dylon dye which can sometimes be found in the US, which is called Dylon Cold Water Dye. This is a different kind of fiber reactive dye, known as Procion MX dye.

Rainbow Rock kits also include Procion MX type dye, so they are much more like the Dylon Cold Water or Dylon Permanent dyes. The same dye is sold by the same company, Duncan Crafts, under the Tulip brand name, as well.

Dylon Permanent Dye and Rainbow Rock dye include the soda ash or other chemicals needed to raise the pH in order to make these fiber reactive dyes work. Dylon Cold Water dye is sold with a separate packet of soda ash for you to add for yourself. Rit dye contains no chemical adjuncts other than salt, but it does contain a type of dye that is of no use to you, since it is a combination of two different types of dye that work on different types of fabric.

To test a dye, you should see if it washes out of your fabric. A good dye will not wash out. If you wash fabric dyed with all-purpose dye five times in very hot water, you will probably end up with faded fabric. In contrast, if fiber reactive dyes are applied correctly, they will last for a hundred washings in hot water. However, the very first washing will remove some dye because not all of the dye you use will attach to the fiber, so the fabric will be lighter after the very first washing even for fiber reactive dye.

Good luck in your science fair project. You will need to reference this message in your bibliography. Here is one appropriate format:

     Burch, Paula E. "Why does the Rit dye package 
     say to add laundry detergent to the dye bath? How 
     does it help?" [Weblog entry.] All About Hand 
     Dyeing Q&A. 18 Mar. 2007. (http://www.pburch.net/
     dyeing/dyelog/B1063361308/C22699859/E20070319101910/) 

End your reference with the date on which you accessed this page.
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