Again, this has been an excellent thread. It has helped organize those random bits of knowledge floating around in my skull for 50+ years. I have a couple of questions still.
1. Besides super glue and epoxies, do you use either carpenters or a hide glue when repairing cracks? I know the new synthetics have advantages but wonder if there is still a place for the old varieties.
2. Flitz and SemiChrome are both very fine, as in grit, polishing compounds. Has anyone used either for bolts or the other bits that would have been polished or does it remove too much. My distant memory, the part that still works, recalls a Flitz seller at the local shows that sat polishing an old Colt DA revolver (prewar) at every show I ran into him at. His point was to prove that it didn't harm the original deep blue finish.
While I realize we have Ren Wax and other better protective products; I recall that in the 50s & 60s as a teen, my favorite protective coatings were Hoppes No.9, Rig and Johnson's paste floor wax for those seldom used pieces. Johnsons served me well on wood and metal for decades in the humid Texas and Louisiana Gulf Coast environment.
I don't use carpenter's glue or hide glue for stock cracks. While they may (will) hold securely if the crack is well cleaned out to expose fresh wood and clamped positively, they aren't as strong as epoxy, nor as water proof. In cabinet work, I use hide glue for joinery that may have to come apart for repair a century down the road. Water/steam is the solvent for hide glue. There were times I blessed old craftsman for using hide glue when I had to un-do their work- but on the other hand perhaps the joinery would have still been sound had they used epoxy 200 years ago.
One glue I just can't warm up to is Gorilla Glue, and others of its ilk.
Epoxy will bond with strength if it's impossible, or undesirable, to clamp a crack shut. Yellow glue won't do that very well.
Nothing wrong with Hoppes, Rig, or Johnson's Wax, IMO. Sure, there are better products, but that old stuff is still plenty good.