Pam thanks for the suggestion but does a candle really heat up the nail quickly enough? even in a gas burner it takes 10 seconds or more to burn off the plastic and get it hot enough to burn through 12 holes without getting too cold..
but in any rate Des has a suggestion about the taper drill and i'll be getting one of those.
P.S. I did find some 50% H202 at a hydroponics store which the directions say only need 2ml per 10L so i'll be using that for a while.