I found this link with useful tips and information on the use of various materials. Here's an interesting excerpt on the use of pastels:
DECOUPAGE: PASTELS
oil pastels I have the advantage that it can be used on surfaces treated with either chalk or watercolor, or on surfaces covered with enamel or oil. They can also be used as is, creating textures, or shades of color, may subsequently be diluted with turpentine and so you get the effect of seeming real oil paintings, allowing those who are not familiar with the paintings and palettes in any way to get quality results. The secret is to get some pleasing strokes, and this technique is accomplished by drilling a little more and using a little more patience.
If you have limited time, keep in mind that the funds created with pastels require a relatively long drying time (but will not be a problem, right?, Put to rest for a few hours because your work to dry and do in the meantime something else?), even if they have the advantage that it can be changed or adjusted. It should, however, use soft brush and good quality.
how:
· Roll out the bottom fading between them the various shades of the same color
· Bath a soft brush in turpentine (but be careful not to soak it too much) and pass it quickly, without calcium, on the surface. Let dry.
· Glue the cutouts. When dry, cover the entire surface with glue. If you want to look soft and bright at all, finished with neutral wax.
