Davespil wrote:I don't have any foam from blisters so would a foam paintbrush work?
Yep. The cheap foam sponge brushes have about the same cell size/density as blister pack foam. Better than makeup brushes, in my opinion, as there's more foam in the head to work with. You need to tear out chunks to give it the rough edge needed for a random, mottled pattern, so the extra material is a good thing. Really, though, any soft, finely grained open-cell foam will work. As many of those foam brushes as I have, I always end up using scraps from packaging, air conditioner weather sealing strips, etc.
Should I waterdown the paint or keep it thick? People always say to water paint down but I find that out of the pot it covers much better and there is no rneed to paint over something 2-4 times.
Keep it thick, but apply it sparingly. Again, you want an irregular, mottled application - that's why you use a shredded sponge. If you overload it, you're just going to end up splodging on big globs of paint. Load up a corner, smear it around on a palette to distribute the paint over the face of the sponge, then gently dab off on a paper towel, if necessary. Load the sponge more like you plan to drybrush than lay down a basecoat.
More generally, people recommend thinning because of the smoothness of the finish (thick paint is viscous enough to show brush strokes, thin paint is self-leveling and flows off a brush more readily) and the greater flexibility of translucent paint. Thicker paint definitely covers better, but that's not always desirable - dilute paint aids in blending, softening layer transitions and making subtle glazing possible. "Always thin your paint" is common advice thrown at beginners, because it's something they should learn as soon as possible, if they want to improve. In reality, thinning is a very fluid [rimshot] practice - something that you adjust, on the fly, to the task at hand.