I saw this on the web today and thought it was a good idea especially since i cant find a local store who sells Alum Blocks and i have the pencil and I don't really like it if you did try this how long did it take, also did it work i would think it is the same thing as one from classic shaving or a comparable brand also would make a neat science experiment if you have kids of whatever
I am going to try it when/if i can find Alum Powder so I'll let you know how it turns out
http://chemistry.about.com/cs/howtos/ht/alumcrystal.htm