I found that if I sprayed water on the outside of my papercrete dome on a warm dry day that the temperature on the inside would drop substantially from evaporative cooling. I was planning on painting it at some point to seal it, but this may be too big an advantage to ignore.
The problem is that I can find very little info on water permeable paints. There is a lot on vapor permeable paint, but that will not really help with this application as I want the water to soak in. I may just leave it unpainted, but it looks kind of grey and blotchy so it would be nice if I could even out the color at least. Also I want it to be a slightly dark color so that it blends in to the woods a bit.
Things I am looking into are whitewash, milk paint, tempera and colored chalk powder. Any thoughts?
