I recently bought the new book Pastel Pointers by Richard McKinley. The book included a DVD in which Richard showed how to use wet underpaintings. I thought I'd give it a try. I am not a fan of sanded papers, but had some leftovers of several brands, and decided to experiment. I used UArt, LeCarte and later - Wallis.
In the photo below you will see two UArt papers on the left and a LeCarte paper bottom right. I have blocked in the composition using the reference photo on the top right. I used the same colors of hard pastels for all.
Then I tried several different wet washes to see which I liked the best. In the photo below you will see that I added Wallis to the experiment. Because the LeCarte's grit was dissolved (you can see the white patches), I just threw that away. Because LeCarte uses a vegetable based grit, it was too fragile for a wet wash.
You can see that the Wallis was the most vibrant and had a nice watercolor effect. The others were pretty boring. I then started to add more color with softer pastels to all three papers. I really didn't like the feel of the UArt paper and since the Wallis was much more interesting, I worked on that alone. Below, you will see the finished painting. It was a good experiment overall, but I still don't really enjoy using sanded papers. I prefer a softer feel and suede mat board is my favorite.