Name: Paul
Message: Hi. I just have a quick question - is it possible to thicken a dye? I'm making my own t-shirt designs with stencils and I'd like to apply the dye with a stencil brush or foam roller. I'd be stencilling onto white or light-colored 100% cotton t-shirts. I was thinking of using a Procion MX type dye and thickening it with guar gum. Would that work?

Guar gum is not ideal, because it reacts with fiber reactive dyes, reducing the amount of dye that actually reaches your fabric. Most people who thicken their Procion MX dyes use either sodium alginate or Superclear. See "Sodium alginate, Superclear, and other dye thickeners". There are two types of alginate, F and SH. Alginate F is used for silk, and alginate SH is used for cotton. (Amazon is one possible source for Jacquard brand alginate SH.) Here's a recipe for using alginate SH:

Chemical Water (Dye Mix)
2 cups water (0.5 liter)
1 tsp. of Alginate SH (5 ml)
1/8 cup Urea (2 tablespoons or 30 ml)
Mix with 2 tablespoons Procion MX dye powder (30 ml)
Either add 1 teaspoon (5 ml) of soda ash to the dye mixture,
or presoak the fabric in soda ash (1 cup per gallon or
250 ml per four liters) and use while still damp or after
line-drying.

I have found that thickened dye may solidify if not used within a few days.

You can use guar gum for thickening acid dyes, when dyeing animal fibers (wool or silk) or nylon. Acid dyes cannot be used on cotton.

By the way, I did make one stencilled shirt with acrylic paint and fabric medium. It turned out well, but I don't like the stiffness of the paint. I'd still use paint for light colors on a dark shirt, though.

When you want to try the same technique with dilute bleach or other discharge agents, don't use alginate to thicken your bleach, because the bleach quickly breaks down the thickener. Instead use Monogum or bleach thickener, or for small designs try the thickened bleach in a Clorox Bleach Pen. Alternatively, you can use a liquid or gel formula dishwasher detergent, which has bleach and thickeners included in the formula. Both requires the same post-discharge neutralization, using either peroxide, chlorine-free oxygen 'bleach', or Anti-chlor.

Not all dark shirts will bleach well, depending on the dye used on them originally, but Dharma Trading Company sells black t-shirts which are guaranteed to discharge to white.

You can use discharge dyeing to produce white or pale designs on a dark background, or to create white spots to dye over to create bright colors on a black or dark background. The feel of the fabric is much nicer than with paint.