I make my own painting panels. I do that for several reasons, the first and most important is that I want them oil primed. The panels you buy at the art supply store are primed with acrylic. Oil paint "sits " much better on an oil primer and it dries in less, feels better under the brush, and binds better with an oil ground chemically. The other reason is, I can make them cheaper than the commercial boards. Much cheaper.
I buy Masonite (hard board ) panels at a big box lumberyard that cuts them into 24 x 48 pieces they call handypanels .They are much easier to cut alone on a table saw . Putting a 4' by 8' sheet of hard board through a table saw alone is almost impossible. I set the fence to give me the width I want, in this case 18' and then I carefully feed my stock through the saw. My wife is inside so if I feed my hand in there too, I stand some chance of a rescue. Don't use a table saw when there is no one else around.
My table saw is a hundred and fifty dollar Sear special. I wouldn't want to build kitchen cabinets with it, but for cutting painting panels it works just fine. It also has folding legs so I can store it in between uses. I ended up with some left over material after cutting my 18 x 24 s so I used that to make 11 x14"s and 8 x 10" s. I wasted almost none of the hardboard.
Out in my back yard I have set up a couple of sawhorses with several 2 x 4s running between them and a scrap of plywood to set my tools on at one end. I do this about twice a year so I have the whole setup ready to be used when I need it.
Here are my materials for priming the panels. I have a can of oil-alkyd primer from Sherwin Williams. (Correction, the formula on this product has been changed and I am now using Zinsser OIL BASED primer. They are best known for shellac based primer, but I am using the oil based now.) I don't like the acrylic, but in some states oil based primer has been made illegal. If that's all you can get, it will have to do, but it is vastly inferior to the oil base. Acrylic gesso is the other choice. I dislike that stuff and I have seen it peel of off of a panel, but lots of people use it. It is a drag to sand, like sanding rubber.
I put the primer into a roller pan and thin it till it is like cream with mineral spirits. Then I lay it onto the panels with a foam "hotdog" roller. A hotdog roller is shaped just like a hotdog, that is it is rounded at the ends so it doesn't leave an edge mark behind. I buy the ones that promise a super smooth finish. I also have a plastic disposable roller pan liner , which I use over and over until I am forced to dispose of it when it gets too loaded up with dried paint.
Here I am happily rolling on my primer with a steak cooking on the grill behind me. I put a coat on lengthwise being careful to leave no raised lap marks in the primer. That's easy. The I throw them onto the grass to dry. I like to do this on a hot afternoon as it helps my drying times, and in a couple of hours they are dry.
Notice the panels are a little warped at this point. Thats because I have only painted one side, and that side has shrunk. When I am finished with the panels I will paint the backs with latex paint that I have left over from some household project. It doesn't matter much what color it is. This is important for another reason. I want to seal up that board as best I can. I have known people to paint the edges too, but I don't bother.
In an hour or so in the sun the boards dry enough to recieve a second coat. The second coat I apply across the panel, going the other way than the first coat. Then I let them dry in the sun again until they are ready to sand.
I use a palm sander with a piece of 150 paper on it. 150, seems to be exactly the right grade. You can hand sand these if you don't have a sander. The sanding goes real fast. The primer is made to be sanded. I can sand an 18 x 24 panel in less than a minute. That's why I used the super smooth roller .
Here is my whole setup for doing this.
The panels I make are a LOT better than the commercially available panels. I will show you in an upcoming post, my boxes for transporting panels.