Don't know how Von is doing it but I use to do it for a sheath that I used to store my fish cleaning knife in in the tackle box. That first knife and sheath were all about experimenting. I learned the hard way the knife still needs to be dry before it goes back into the sheath! Also learned like any treatment to leather it has to be refreshed every so often.
For myself I always used a mix of 3 -1 ratio of, the following 3parts beeswax and 1 part paraffin wax! Actually at this moment I can't explain the why. However it was something I discovered if I used 100% beeswax there was a problem. However in my feeble mind I can't remember what the problem was!! See what old age does for you!!
As to the how of hot waxing. I have done it two ways. Get the wax hot enough to spread with throw away paint brush. Then heat the sheath with heat gun. Being careful not to burn the leather. All you are looking for it to let as much as wax can soak into the leather as possible. Let it cool and buff of any excess with a soft cloth.
The other way is to heat to liquid the wax. Then let cool till just before it starts to congeal again. I have poured it inside the sheath and then after a bit pour it back out. I then dipped the outside of the sheath!
Any way you do it the leather will only take so much of the wax and the excess can be buffed off with a good soft cloth! The buffing actually helps to push it into the leather by the heat created by buffing!!
One thing to keep in mind when doing the hot waxing is that the sheath needs to have a drain hole in the bottom and to do this I leave the welt back a 1/4 inch from the end of the sheath. The wax is straight parriffin wax and heated to 230 - 240F with the sheaths in the oven at 100F to pre-heat (which aids in opening the pores of the leather to except the wax) while the wax heats which takes about 15-20 minutes. I dip the sheath into the hot wax with the drain hole up which allows the air inside to escape and the wax to get all the way to the same level as the outside so dip, hold for 4 seconds and out again. There is ony a few seconds for all the wax to be sucked into the leather and while it is hot to hold the sheath is reversed and the bottm end is dipped in for the same time. Generally there is only a short part of the sheath to do from this end as my wax tin is 6 1/2 inches deep and the wax easily travels in through the drain hole to thoroughly coat the remaining portion of the inside of the sheath. I fit the knife while the leather is hot so it forms the shape then remove the knife till it all cools down again and this leaves the sheath hard formed (almost like kydex) and protects against any inclement weather while hunting or fishing. A go-over with Renaisance wax every so often keeps the visual looking bright and shiney. I have an old video I did but will do another one today on the process.
garry...I suspect that process makes for the best hard use leather sheath around...I did try it once a couple years ago after watching your video. Absolutely waterproof. I didn't stick with it because I couldn't the little foo-foo artistic things I was trying on my sheaths back then...lol.