What is an underwash? With a pastel painting, it is the first layer of the painting. Why are underwashes needed? Because it either covers the media, saving you from using too much soft pastels, or has a desirous effect with your painting. We will discuss both. In both of these examples, I am using a 10″x8″ Ampersand Pastel Board.
Example #1 Watercolor Underwash
In this example I used watercolor as a first step underneath my pastel painting.
Pros: Watercolors have a cool effect. The water spreads the pigment and the clouds look soft, distant trees look realistic without much effort. Let the watercolors do what watercolors do…..spread on their own. Do you see under the clouds? It looks as if rain is descending on the ground….I did not do this intentionally, the watercolors spread on their own and like magic it looks realistic.
Cons: When dry, the watercolors dry very, very light. Apply dark if possible.
When applying soft pastels on top, do not cover the whole painting. Let the watercolor underwash show through. This enables you to achieve a 3D effect, effortlessly.
Example #2 Turpentine and Pastel Underwash
In this example I scribbled a little pastel color and blended it on my board with turpentine and a bristle brush. A little goes a long way.
Pros: It takes very little pastel scribbled on your board to cover the entire surface. It actually takes a lot less than what I used. Just apply a tiny bit of pastel color and with a clean bristle brush, spread it with turpentine. Pastels are expensive, but if you use this method you will not waste much soft pastel.
Cons: Not much of a 3D effect, rather flat, but many layers can be applied for a dimensional look.
Both methods are fun. These two examples were done on Ampersand Pastel Boards. These methods will NOT work with regular pastel paper. The water with the watercolor and the turpentine in method #2 will destroy regular pastel paper.
Explore and have fun! Layer and see where it takes you.
Let's Paint Nature! 
It looks great! Applying dry media over wet is a great way to touch-up or enhance a work of art. I’m trying colored pencils over colored inks. I’ve also had success with colored pencils over watercolors.
What excellent techniques! Thank you for sharing. I’ve tried pastel pencil over watercolor on cold press paper, but not colored pencil. It’s fun to mix media and see what happens! 🙂