you can use two thinks together,
mould release
http://cgi.ebay.com/Partall-Paste-Wax-2-Mold-Release-for-Carbon-Fiber-24oz_W0QQitemZ110464274577QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item19b82f1091#ht_931wt_939
, and PVA (polyvynial (sp.?) alcohol, it dryes like a film like glad wrap...