Seems like the tank heaters are key. Just did my whitetail skull in 15 days using a tank heater in the barn. Now it is resting in dawn and warm water for however long that will take. Couple of mule deer skulls out there rotting now.
Word of warning on Rid X. I had the whitetail skull in that at first and taped a bag around the top of the bucket and across the brow tines. Apparently the warm Rid X fumes carried a blue green mist on the exposed antlers. Was a bit worried but after going back to clean warm water, the stains disappeared. That said, won't use RidX on them again as they rot fine without it.
