another putty sanding trick is not to sand it!
try a Q-tip w/ nail polish remover after the putty has set up some, but not completely hardened.
for the complete scoop, go to:
http://www.aircraftresourcecenter.com
click on "tools'n' tips" on the top menu,
pick "Filling" off the list
then "Filling without sanding" off the new page
(currently bottom row, 3rd item)
notes: requires acetone based nail polish remover or you can substitute denautured alcohol.
!! USE ONLY WITH ADULT SUPERVISION IN A WELL VENTILATED AREA!!
works w/ auto body filler too.
DO NOT TEST ON YOUR MOST IMPORTANT KIT !!
ed.