And then there are some that don't find it to be a problem at all and really like the looks of a sheath when you use hot oil/wax. I will agree that it has to be done right or it can be a mess. I use a little more wax than a 50/50 mix and it is hard when cool.
While the mix will burn it is not nearly as flammable as you would think. Neither neat’s-foot oil nor bees wax has a flash point. They make candles out of bees wax so it is not like it is going to explode in flame. I took a tin of the mix and held a torch under it until it started boiling off with lots of smoke. I then tried to light the smoke. Nothing happened. I tried to light the really hot melted mix and it did burn like a candle. When I took the flame from the torch away it burned for a few seconds and then went out. It was still smoking. I use a crock pot and the oil/wax never gets any where near hot enough to smoke much less burn.
I don't worry about ruining the leather by overheating any more than I worry about burning chicken when I bake it. You don't leave the chicken in the oven until it reaches the temperature of the oven, don't leave the leather in the oil until it reaches the temperature of the oil either. I bring the mix up to temperature and dip the sheath in the mix for 4 to 5 seconds. This lets the leather warm up so the mix will penetrate, but is not long enough to fry the leather. I then place the sheath upside down on a grate over the crock pot for a few seconds to drain. I never use a hair dryer or heat gun on leather. In close to a thousand sheaths I have never had a problem with a "cooked" sheath.
As far as rotting goes I haven't seen any information that would back up one finish over another. I do know that my linesman's belt was finished with a wax finish and so was my dad's. I bought mine in 1967 and he bought his in the early 1930's. They were kept in a bin on a truck when not used, so they were meant to take abuse and hold up. He hung his in the barn after he was through with it and about 40 years later it was still in good shape. The companies that make the belts still don't use super sheen to finish them.
I don't know how much of the mix others try to get "soaked" into the leather, but I have never had a problem with it leaking out when it gets warm. And it does get warm in South Georgia.
I use an old crock pot for the mix. It works great and you don't have to worry about over heating the oil. While the oil is hot, it is not hot enough that it will blister or burn you any more than soup would. I don't put my hands in the soup either. When you are done, you just put the lid back on and unplug it.
There are several areas that that are concerns with using the hot oil/wax mix, in my opinion, that have not been addressed. You have to plan ahead to use this finish. It takes time to bring the mix up to temperature in a crock pot and it must be hot enough or you will get a mess. You can't rush it at all. It does take some practice to get right or you will end up with exactly what Bossdog said you will get. A greasy, burnt mess. It does not work well with dyes at all, so I don’t use it on sheaths that need to be dyed. I also don’t use it on exotic skins like alligator. Alligator is dyed and finished as it comes from the tannery and the mix doesn’t work well with it. The last thing is, you will catch some flak from sheath makers about using the mix, although the customers love it. Sandy made a few remarks about it to me, realized I like it because the look I was getting is what I was after and he adopted me anyway.
While it is some trouble the sheaths last and the looks are worth the effort to me.
I just hope I don't get banned for having a different opinion about the hot oil/wax from the pro’s Paul and Dave and the forum owner Boss Dog.
I kind of like it around here.