ONE OF THE primary ingredients for thick paint is chalk, otherwise known as Calcium Carbonate. The thicker I paint the more chalk I use. So it is important to have a good source of inexpensive chalk. I recently found a source that is half as much as the previous chalk (currently $13.25 for five pounds and free shipping).
Like painters have done for centuries I add chalk to my paint to give it body. Chalk has very low tinting strength so it doesn’t make your paint lighter in value, in fact, when you add it to transparent media the mixture becomes almost transparent. I say almost because it does impart a slight milkiness to the mixture. I add chalk both to my oil paints as well as to my acrylics when I need to make a very thick mixture. When you add chalk to acrylics it will make them more absorbent so when you are finished painting be sure to varnish it with a generous coat of acrylic medium.
Although I have experimented with more complex mixtures lately I simply add chalk to my paint or add chalk to Gamblin’s G-gel for a thicker medium to oil up my canvas (to see why I do this go here). If you would like more info on more complex recipes go here.
Brad Teare January 2012