disappearing pastels

Pastels only work well on flat finishes where the paint gives a little tooth to hold the particles. On gloss finishes, it's not much more than dust which will easily wipe off. On a flat finish, you normally want to slightly overdue the pastel effects & then seal with a flat top coat. The spray will blow some of the pastel off, reducing the desired effect. Unsealed pastels will deteriorate even on a flat paint finish if not sealed.

Regards, Rick

If you overcoat the model with clear flat, this will virtually negate the effect of pastels. I don't know the physics behind this but it happens.