Name: Line

Message: Hi, I'm planning to dye a sweatshirt that has a silkscreened design on it.  I think this will work because my sister in law has done other garments like this and I've loved them. 

Silkscreened designs are unaffected by dyeing, in my experience, but you must keep the color light enough that the design does not simply seem to disappear, due to loss of contrast.  

It's a white sweatshirt - Hanes® Heavyweight cotton poly blend.  I have a large on order - will the dyeing process cause any shrinkage in this kind of garment?  I hope I didn't miss this on the website - I did do a search.

There are two main classes of dyes for cotton: hot water dyes, and cool water dyes. Hot water dyes require nearly boiling water to perform their best, which will, of course, cause as much cotton shrinkage as is possible. Hot water dyes are widely available as Rit® Dye, Tintex® Easy Fabric Dye, DEKA® L dye, etc. However, you should avoid hot water dyes when dyeing cotton clothing, anyway. In particular, all-purpose dyes perform poorly on cotton clothing, fading quickly in the laundry, and (as a bonus) possibly ruining other clothing you wash the dyed garments with, if you are not meticulous about sorting.

In contrast, a good cool water fiber reactive dye will not require boiling water. The most popular of fiber reactive dyes, Procion MX dye, can be used in water as cool as 70°F (21°C), which will not shrink anything. It will also produce brighter, prettier results than all-purpose dye can, and will last a hundred times longer in the laundry without ever requiring you to wash it with similar colors. You will use soda ash to fix the dye, instead of heat; this works only with fiber reactive dyes, never with all-purpose dyes. Soda ash is a common household chemical, found in washing soda and most laundry detergents; you can buy it from the same company that sells you your Procion MX dye, or you can get it from your local hardware store in the swimming pools supply section.

However, the dyeing process absolutely requires a thorough washing afterwards, preferably washing in hot water of 140°F or higher, to remove excess unreacted dye. As you know, cotton does shrink when first washed, especially in hot water. If it is very important to you to maintain the pre-washing size of the shirt, you will have to wash out only in cool water. Cool water does not work nearly as efficiently in washing out fiber reactive dyes, so, if you do not use hot water for your washing out, you will have to be cautious with the garment, washing it separately or only with similar colors, until all of the excess dye has been removed, which could take many, many washings in cool water. It will work fine, though. You can do it. Just be aware that if the dyed clothing is washed in hot water for the first time even a year later, more dye will come out that did not come out in cool water. If you're ever going to wash in hot water, it's as well to do so right after dyeing, so that you know there is no unattached dye left to run in hot water.

As a lazy person, I prefer to buy clothing in the size that will fit even after machine washing and drying. This can save a lot of work over the lifetime of the garment. If I were you, I'd buy one size larger so that I could wash in hot water with impunity.

It is very important to note that while you can dye the cotton in your blended sweatshirt, you cannot dye the polyester. A 50% cotton/50% polyester blend will produce a nice pastel, if you use plenty of dye. The same dyes will produce a brilliant color on a 100% cotton sweatshirt. It is almost always preferable to dye a 100% cotton (or 100% rayon or 100% silk) garment. 50% cotton is fine if you don't mind pastel colors, though. Polyester will not accept any dyes that work on cotton; it will just stay white. (The special dye that will work on polyester requires that you boil the garment with the dye for an hour, which will ruin many garments! Don't even bother to try to dye the polyester fiber in your blended clothing.) Hanes does sell sweatshirts that are 100% cotton on the surface and 80% cotton on the backing, which would be ideal for dyeing, as long as there is no stain-resistant finish. 80% cotton generally dyes quite well.

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