I'm painting over builders grade paint, and I know it's going to be very "thirsty". I have a lot of light colored paints left over from previous projects that I'm never going to use again in an eggshell sheen (whites and yellows that mix into a light yellow). I was thinking of mixing them all in a 5 gallon bucket and using that as "primer". Do you think I'm asking for trouble? My topcoat is a tan Ben Moore eggshell.