Well, that’s interesting.
Acrylic ink, which I use for love of waterproofness and opacity and so forth, is indeed waterproof.
Evidentally it’s not milkproof.
I laid down some treetrunks in acrylic ink and glazed over them with white gouache. They weren’t receding as much as I’d like after multiple coats, so I went to the next Big Gun–casein, a milk-based paint that’s more opaque than gouache, but still workable for awhile after drying, unlike acrylic.
And I discovered, about a minute afterwards, that the casein picked the pigment right out of the acrylic ink and turned into a tan smear.
Painting was salvaged through hasty paper-towel use, and a little experimentation would indicate that dripping and patting the casein is reasonably safe and delivers the white-over-brown effect I was after, but it was still an interesting discovery. Ultimately a fairly happy accident–the globs and splotches look very bark-like–but kind’ve a surprise. Water does not equal milk. Who knew?
This is why I don’t use oil paints–the notion of linseed oil and turpentine and god knows what toxic solvents would overwhelm my feeble brain. I got a B in AP Chemistry because I always typed my lab reports and wrote clear, lucid prose, not because I ever made any of the experiments work. (I maintain that this is entirely the wrong way to teach kids science, but that’s another rant for another day…)
Originally published at Tea with the Squash God. You can comment here or there.