I use gesso and add it to paint. I use a little bit at a time. It last for a very long time and it cost me about $8.00.
Recipe Water – 1 to 2 Parts (more or less as needed for consistency)Tooth – 2 PartsPigment – 1 to 2 Parts
So for example, I put in a cup of glue, a cup or a little more of water, a cup of baby powder and a cup or so of left over paint. Think pancake batter or syrup for consistency. Mix well and test for coverage.
Most of the time I make it up with equal amounts of everything and it’s just fine. I like to see through mine, if you want yours to give better coverage, use more pigment.
Try dap plaster add it to paint,
I use Gesso to make my own chalk paint.