where do you find something like this - every article i have read about using masonite specifies untempored but i have asked numerous sources and been unable to find this - what happens if i just go to home depot and use what they have there????? thanks for all your help.

My husband uses Masonite a lot for his smaller paintings, only Masonite for his daily paintings. He gets a sheet from Home Depot and cuts it to size. Then, he sands, gessos, sands, gessos, sands, and puts on an undercoat of thinned out burnt sienna. You could use an undercoat of whatever color you want or not use an undercoat at all. So yes, Home Depot or other hardware store Masonite will work fine.

Try using MDF board. Medium density fiberboard. It is lighter than masonite, more uniform, stays flatter and sands easily. All the large home project stores carry it. It is inexpensive and easy to cut. I usually cradle any panel over 16x20.