I've used Boco's tanning method several times now for Beaver. The smaller hides turned out great. Had some issues with the larger hides. I posed some questions about alum tanning on a taxidermy site, and they gave me some recommendations (basically tweaks to Boco's method) that have worked out for me.
Tweaks:
. Instead of 1lb of Alum to 1Gal water. I'm using 8oz Alum + 8oz Salt / Gallon.
. Add skins at the lower PH, which allows the Alum to penetrate deeply into the hide.
. After a few hours add washing soda to raise the PH and set the Alum. Not mixed with water.
Here is where I'm at with this method: (Based on 5 L/XL Beaver pelts at a time)
Out of the pickle let them hang for 20min and wring them out. You don't want the hides to be filled with pickle. Like a squeezed out sponge.
8 Gallons water. 4lbs Aluminum Sulphate 4lbs Salt (based on the salt you use this is about 8 cups for me). Mix well
Add skins. Don't over crowd. Should be somewhat floating.
After 2 or 3 hours. I pull/drain/ring the hides over the solution and set aside.
Add the washing soda (not mixed with water), little at a time until the PH reaches 4. For me and my water I'm at around 16oz. This part takes awhile. If you add too much at one time the foam on top is thick. I'll leave it sit till the foam settles so I can get a proper ph reading.
Add skins back in one at a time.
Leave them sit for 4 days, checking PH at least once a day. My issue, is that after the first day the PH has dropped a bit. So I need to add more washing soda.
Pull them and give them a good RINSE. Don't need soap. Cool water. Need to wash all of the Alum out of the hair. If you don't, after they are fully dry they will emit dust clouds of alum.
If they still emit dust clouds, I'll hang them, reverse the hose on my shop vac and blow them completely out.
I've been having really good results. They come out pretty soft after oiling and stretching. The bigger ones I do put a sander to after they are fleshed, stretched and dried. Before I tan them.
Shout out to Boco. Thank You for sharing your knowledge.