Thanks for the comments on the rocks / mountains.
CaliAnn, when I say dilute acrylics, I mean acrylics that have been watered down to watercolor consistency. I imagine they are a little like acrylic ink, but probably not quite so intense. For example in the rock painting, the sky wash was very watery, and the dark areas put in at the end were getting toward the consistency of heavy cream.
The difference between student grade and artist grade really shows up when you paint this way. Student grade just doesn't have the pigment content for this, at least in my experience -- even with phthalo blue and green. Also, a lot of student grade acrylics have Ti white added, which is not good if you're trying to paint transparently. So I mainly use M. Graham and (left over from back in the day) Daniel Smith acrylics. Most of the paint goes on so dilute that it's actually quite economical in the long run.
I've read some experts say that you need to use fluid acrylics to paint in this style. Perhaps, but the heavy-body artist acrylics I've been using seem just fine to me when diluted.
One big difference is that once the paint sets, you're not going to lift it up by scrubbing. I've actually taken sandpaper to lighten a few small areas of some paintings and liked the result. But those areas are not suitable of painting over at that point.
Another difference is that you don't want to use a plastic palette. It stains, and if the paint dries, you're out of luck. (How could I possibly know that?
) Porcelain works great. If the paint dries, it's easy to clean. You need to mist every few minutes while painting, and put wet sponges in the mixing area and a tight fitting top when not in use.
I started doing this accidentally. I wanted to try painting, and the expert advice was that acrylics are a good place to start. After I got a few supplies and tried a few paintings, I decided I really wanted to try watercolor. I was ready to buy some watercolors, and then read Wendon Blake's "Acrylic Watercolor Painting,"
I keep thinking I should get some real watercolors and try them, but haven't gotten around to it yet.
That's probably more than you wanted to know, but it was fun writing about it.