Here are a couple of my recent plein-aire painting sketches from Tumamoc Hill. This first one was painted with casein in about half an hour as it was still cold up there - you can see the snow on the Catalina Mountains in the distance.
Casein on paper
This one was painted in a little over an hour with my "new" paints: water based encaustics from Cuni http://www.encausticcuni.com This is first time I've used these paints. I really like them. I've always wanted to try encaustics, but never wanted to mess with heating up wax to paint. These paints however work straight out of the tube. It is thought that this is same formula used by the ancient greeks and romans to paint the famous Fayum mummy portraits, which are still in perfect condition after almost 2,000 years.