Boiling & Simmering flat out SUCK and you can ruin a skull quick doing it! Boiling can and will cause bone to break done especially with some of the chemical I've heard some people say they put in the watter. It can also cause grease to set into the bone and cause discoloration
I have to disagree, I did mine and a buddies deer this year, using a post that had been on this site as a guide. Boiled on a propane burner, low and slow. Took about a day taking it out and cleaning all the flesh/brains etc. Let sit out and dry. Coated in a paste of peroxide and bleach for 24 hours. Took out hosed off and let dry. Both turned out awesome. Euro mount in 3 days. Nearly instant gratification.
I'm sure there are other ways that are less labor intensive. For me, spending a day out drinking some cold beer and boiling deer skulls is my happy place
