Thanks smasha, I'll get some Talc for my tube. (and will rinse my spare free of the corn starch!)

As for Talc for baby / body care, there are some health concerns. Do a Goggle for "Dangers of talcum powder" or check this link:
http://www.livestrong.com/article/23...owder-dangers/

I don't think we need to be concerned with health risks when using talc for lubing a tube (small amounts, outdoors, not big clouds of the stuff in the bathroom). But those links will point out reasons to avoid it as a personal care product.