Any one use it? I bought some pints of tempra fro dd, but we go through the stuff like water! I considered getting the gallow size, but I am thinking that may be too much, and I'm sure after it is opened, the paint has some kind of expiration date, right? So I thought maybe the powdered kind would be a good buy. I m just worried that it wouldn't be as vibrant? Has anyone used it and what brand? Thanks!