Re: Are Sta-Wet pallets firm enough to mix colours?
I like the Sta-Wet palette because of their sizes and shapes - not too deep and they fit a back-pack, extra computer case, etc.
The sponge can be replaced, when it's time, by a ShamWow or other synthetic chamois. Heck, a real chamois could be used, but that's kind of expensive. If kept closed for more than a couple days, though, both the sponge or the chamois will often begin to show signs of mold, so open at least daily.
A piece of tempered glass cut smaller than the sponge is fantastic for mixing, but an occasional spritz is needed, but it is also necessary if painting on the absorbent palette paper because the paper does not keep the surface of the paint moist.