One of the first things we go over in my workshops is how to prepare the boards for painting. Since it is an important first step before beginning, I thought it would a good time to talk about the surface I paint on. The materials needed are acid free Gesso, jars to mix in, binder medium, a flat brush (I use a two inch brush), and 1/8” or 1/4” hardboard, either tempered or untempered. The hardboard has raised plenty of questions about whether it should be untempered, or tempered. I use both, but untempered mostly. Remember that hardboard is actually wood, so seal it before applying gesso, and if you want to dig into the tempered/untempered debate, this link is excellent (http://www.ampersandart.com/tips/archivalinfo.html). I buy the sheets in 4’x8’ sheets and use a table saw to cut it up into the sizes I need.
Once my boards have been cut, I coat them with binder medium only on the gesso side. Chroma Acrylics (the guys that make my paint) make this and it works to seal everything into the board, keeping the stuff in the board from migrating into my paint. Now the sealed boards, which dry quickly, are ready for gesso. I mix my gesso with some water in the Ball jars, making it thinner, and close to the consistency of a thin pancake batter. I want a surface texture of a very slight canvas feel, so I apply each layer in alternating directions.
When all of my boards are coated and uniformly white, I let them sit for 24 hours, then I lightly dry sand them. This is just to take down any burrs or surface imperfections, and finally I apply one last coat of gesso. I do not coat the back or sides of the board. Some coating gets on the sides, but it’s not intentional.
The boards are now ready to paint on. If you are doing boards much larger than 8” x 10”, I would use the 1/4” thickness board, and if they are 24” x 36” or larger, I suggest that you glue a wooden support frame on the back. These coated boards will warp, so make sure you store them flat and supported. There’s nothing worse than a finished painting that begins to bow or warp, although there are ways to correct it.
If this all seems a bit much or you don’t have anyone to cut the boards for you (though Home Depot will often cut them in the store for you), you can buy a commercial board. There are many choices today, flat boards, clay boards, flat boards attached to a wooden frame, etc. and they are mostly very good quality. I have found that my paintings look slightly different, depending on the particular board, due to the finish of the boards surface and its absorbency, so it’s another reason that I prefer making my own. Hope this helps you get started. Happy painting…get after it!