Hi Beth
I am so pleased that my idea worked. (should patert it)
I have used paperclay for all sorts of different projects, from sculpting dolls faces to adding ugly faces to the covers of my sketchbooks ( to personalise them) It is a wonderful product. I don't think turps will affect it but if the varnish seal isn't perfect, water will soften it if you soak the brush handles for a long time. The manufacturers say that it can be be rewet and reused but I have found when I have tried to rewet it, it loses its stickiness.