..you can use talc in shellac as a filler...
"FINALLY
Talc is also used as a very fine abrasive, a lubricant on bench-tops, machinery, drawer runners, etc. and can be added to shellac as a grain filler. Our talc is much finer than ordinary body talc and completely free from perfumes that may harm a finish. It is also ideal for use as a body talc for people who are allergic to perfumes and other additives. There are many more practical uses for this amazing powder, from soaking up oil spills to ................ well, let your imagination run wild. "
Shellac & Talc
Have fun.