Preparing paper for pastels is a lot of fun. Start with watercolor paper (I like a large size). Tear off a sheet and put it on a table or other surface. (Be sure to put something like newspapers or wax paper down to protect your table; this will get messy.) Now, take watercolors or gouache or ink or whatever paint you like, and apply it to the paper. You have complete freedom here: wet the paper first, or leave it dry. Brush the colors on or drip them or roll them on with an ink roller or flick them from the end of a toothbrush with your thumb. Or do all of the above, in successive layers. You can make a lot of scratchy, wavy lines that look like ripples, by using a very old, crappy brush. (Next time the bristles of a brush get all splayed out and raggedy, and you want to throw it away, think again! It's perfect for this.) For a dramatic effect, you can dust a little metallic powder on the surface.
When the paper is completely dry again, you are ready to apply the pastel ground. There are several different products you can use for this. Acrylic Pastel Ground is one. Pumice Gel is another. In either case, use a palette knife to scoop the gel out of the jar and transfer it to the paper. Don't fuss over this; move quickly so you can seal up the jar and wipe off the knife before unwanted hardening occurs. Now use your roller to spread the gel evenly across the surface of the paper. Go back and forth several times, both ways: top to bottom and side to side. If you find that the edges of the roller are leaving long, straight grooves in the gel, try to work over those areas for better evenness. Now clean your roller and hang up the paper to dry.
It makes sense to prepare several sheets of paper while you are at it. The most strategic way to do this is to do each of the stages to all the sheets at the same time. So, when you are applying your gouache or ink to the paper, do it to all the sheets and let them dry. Then put all that away and get ready to roll your pastel ground onto all your sheets in quick succession: have a drying rack or clothesline ready, and get a plastic bag or some cling wrap that you can use to wrap your roller in between sheets and prevent the gel from drying on the roller (because this will ruin the smooth surface of the roller). Some of these gels look cloudy while wet, but they become more transparent when they dry.
Once the gel is perfectly dry, you can apply your pastels. The pastel sticks very well and acquires a pleasantly rough look.
