Cooling the blocks by touching the bottoms to a damp sponge or touching the sprue with a sponge is ok to get the temp of the blocks down will reduce the likelihood of frosting. Also using two molds in tandem will allow for more cooldown time. Use of an aluminum heatsink under the blocks will also help. These are all timeproven ways that work well. Nothing gets warped or broken. Frosting, although esthetically displeasing to some folks is not an evil condition. It has absolutely no effect on accuracy whatsoever. Self-inflated gurus and quacking experts that seem to be present on every range always have some comment to make...best is to just ignore them. If you are nevertheless unable to avoid any frosting and it continues to bother you then get a few pads of #0000 steel wool and simply polish it off the noses of your finished rounds. It goes fast, no one will be able to tell the difference and everyone will live happily ever after. LLS