Somebody showed me a trick to "set" chalks--cover with a piece of wax paper and run a brayer over the chalked areas. It embeds the chalks into the paper. Make extra sure any inks or such are dry first! Chalks are great fun and a wonderfully subtle touch for shading. Plus, they last forever (love that).
The "metallic chalks" by Pebbles are an entirely different animal--they're creamy!