Hot scraping is a technique for cleaning the bases of skis and snowboards wihtout using any chemicals or abrasives.
The idea is to use the same process as hot waxing++ but scrape the wax immediately rather then wait for it to cool off and harden. Also, you have to use very soft wax for this, usually cheap warm weather wax is great.
So, the process is:
You should keep doing this until the wax comes off clean.
I recently read about the proper (?) way to hot scrape... which is to heat the ski so much that the (make sure it's soft) wax is liquid on the entire ski, then scrape it. Note that you have to keep moving the iron back and forth to warm the ski equally.
A side effect of that is that the ski (race skis at least) actually change camber i.e. they flatten and then bend the other way...
I tried that and seems to work fine... watching an expensive race ski reversing camber is something... I hope I didn't mess it up for good ;)
This is very important in bad/dirty snow, for instance in the spring, to take all the crap off the base. Also, after tuning the skis, if you used a file for instance, to make sure you extract all the metal particles from the base.
The soft wax is also a very good base layer for the normal wax you'd use, so you get that as well.
The general consensus is that using chemicals to clean the skis is a bad idea. I only use them if I have to patch the base, to make sure that the patching material adheres properly to the base, and I use them localized.
Also, the more you wax the base, the more it gets saturated with wax and the faster the ski gets.