This page will be an ongoing documentation of my pastel making trials.
I am in the process of making soft pastels. I have ultramarine & oxide pigments left over from soapmaking. I also have a few cosmetic clays.
I am going for a soft silky feel. That means I will be using white kaolin clay. If I need a harder pastel, I will add precipitated chalk. But so far, I haven't needed the chalk at all and have been using the weakest solution of gum.
It starts off with a solution of water and gum tragacanth in five dilutions. The stronger the solution, the harder the pastel. So far I have found that unless I use straight clay (I've used white kaolin so far), I need the weakest solution.
The first pastel I made is this 100% white kaolin clay with a medium dilution rate. It's a beautifully soft and silky, off-white pastel.
My next experiment was with red iron oxide. This was completely different than the clay. It remained hard and gritty no matter which solution I used. So I ended up using a a 4:1 ratio of white clay to red iron oxide and the weakest gum solution. I'm happy and surprised that the clay didn't lighten the red iron oxide very much.