I picked up a couple of casein tubes recently. James Gurney has been talking about (and showing) casein on his blog for a couple of months and I was pretty curious about it.
This is basically my first shot at it. I worked pretty small (I think it's around 4x6 inches) on Fredrix Canvas Pad.
The paint handles like nothing I've ever tried before. It's like the love child of oil paints and gouache.
It's a bit runnier than oils but behaves much like it on the brush (I used soft synthetic Filberts). It's really, REALLY matte and incredibly opaque. A single white stroke will cover the darkest background color with ease.
It dries as fast as acrylics or gouaches and to my surprise, I found out that it could be re-wet to mix a new stroke or to soften edges (exactly like gouache but with more body). I read that the surfaces actually closes after a while but that it can take weeks. I'll keep you posted on this.
Thought it dries as fast as acrylics, it doesn't have that tacky feeling to it and anyone used to painting with acrylics will definitely be pleasantly surprised.
So… yeah. I loved it and will keep experimenting with it — namely on other surfaces/grounds.