Pastels-exploding and otherwise

The first pastels I made-from the “Garden Gold” clay dug from the NCC East 40 (photo of this in 5/11/22 post “Back to Earth Pigment”), turned out great. I was not at all prepared for the spectacular failure of the next pastels I attempted to make. If you look at my April 2022 blog post “Don’t Jump in this lake” you will see how I made my first lake pigments. I attempted to make pastels using those lake pigments. They looked great after I made them. Then I came back the next day, to find the pastels had self-destructed; one looked like it had exploded, there were shards and powder all around what had been a well-formed pastel stick just the day before. 

As with other paints, the pigment is what gives the color. For pastels (also watercolor and gouache paints) the binding material is gum arabic, which is resin from the acacia tree. I had used only drops of the gum arabic in the garden gold pastels. I learned the hard way that the amount of gum arabic binder needed to make a usable pastel varies wildly. I suspected the exploding pastel didn’t have enough binder (the gum arabic) and possibly also not enough glycerine. I took the exploded bits and pieces, ground them up, then mixed in a more significant amount of gum arabic and glycerine. One thing I had read is that the glycerine should be proportioned to half of the amount of gum arabic. Glycerine is a natural product that improves the consistency of the pastels, and also has an antimicrobial property. It’s often sold as a moisturizer for skin and is totally non-toxic. I’ve also read that honey can be substituted for the glycerine.

The next day, the re-ground pastels had not self-exploded. But when I picked them up and tried to scribble with them a bit, the pastels broke into bits. I had to conclude I was on the right track-the pastels didn’t self-explode. But when used, they crumbled. So once again, I re-ground them adding even more gum arabic and glycerin. The next day, they were not dry enough to use. Interesting-I had read that pastels took several days to dry, but in my previous attempts, they had dried overnight. I took the fact that they took longer to dry as a clue I was on the right track with adding additional binder (gum arabic). I’m happy to report that three was a charm; the pastels held together well enough to use. Sort of. 


There is such a thing as too much binder-in this case, gum arabic. Too much binder, and the pastels were too hard, the marks made with them thin, not a mice amount of color but a kind of thin lime. I took paintbrush, dipped it in water and scrubbed at the scratchy, too-hard (too much binder) pastel marks, and the pigment dispersed easily into a nice “wash” of color. The nice thing is, with all my bungling about, I’m not wasting anything. Even my “failures” result in something I can still use.

So far I have not been able to make a satisfactory pastel from a rock pigment. More binder or more glycerin or honey perhaps? 

I looked at the price tag of the gum arabic I have been using; it said Pearl Paint, and the price was three dollars something. Ooops. Not only has Pearl paint been closed for about a decade, but gum arabic goes for at least 3 times what was on that price tag. I’ve been using probably 20 year old gum arabic. Maybe that’s an issue-off to the art supply store for me. Once I try some fresh gum arabic I’ll post my results.