Nope Mike not putting words in my mouth. PURE Neatsfoot oil (not neatsfoot compound) was scientifically tested in the laboratory and proved NOT to be harmful to leather. The test was funded by a custom saddle maker and was reported in the Leathercrafter's & Saddlemaker's Journal sometime back - don't remember when or which issue though.
There has been much written/discussed over the years about the "bad" effects of using animal fats on leather, but the fact is animal and fish oils are used in the tanning process! Otherwise vegtan leather would be as hard as a rock and brittle (alcohol/chemical based will in fact dry out vegtan as many of you may have noticed - one reason I add a touch of olive oil to my mix.) Heavy using leather such as harness leather has been more heavily treated with fats & waxes (the process is called stuffing). Montana Pitchblend also had a lab test run on their product which uses mink oil and it was found to have no deleterious effects on good leather.
Now with that said like anything leather goods should be treated sparingly - over oiling can cause "damage" by over softening the sheath or other like product that needs to retain stiffness. And there are bonafide makers that will tell you that neatsfoot will rot threads, but in my experience thousands of leather goods of all kinds I believe that the worst culprits are sweat (salt and water), water damage, and crud/abrasion. Over oiling or over waxing acts like a magnet to crud and the subsequent abrasion. Water damage often occurs when leather is not allowed to PROPERLY dry in between soakings.
As for slickers - I'm like Mike I make mine from antler tips or pieces. You really don't have to have a groove in the piece but if you so desire take a rattail file of the proper size and groove the antler. Round and polish the edges so you don't mark it. Along with antler I use old jeans material or canvas to burnish edges.
Finally thread - first Jim what material is the 7 cord your maker can get for you made of? The reason I ask is you ask whether to prep it just like linen? No matter what thread you use: poly, nylon, linen, or cotton - wax it.
As to size of thread I offer the following image scanned from Al Stohlman's book - The Art of Hand Sewing Leather.
Personally I use 5 strand Barbour's Red Hand Linen - the best in the world IMO - at 6 SPI for most of my seams. It's available at around $35.00 for 1094 yards from Mid-Continent Leather Co, Coweta, OK, USA 1-800-926-2061. How long will it last - Well I bought a roll of 5 strand and 3 strand (I use the 3 strand for sewing on belt linings and doing the stitches around inlays) about two years ago and I have used about half of each roll. Not tooting my horn here, but I'm sure I sew more miles of thread in a month than most of you do in a year so you can see that it's going to last a LONG time for the average user
.
As for strength - well most of my work is actually gun rigs (for every sheath I make I probably make 10 holsters) and I use the 5 strand on my main seams and those seams see a whole lot more wear and tear than the average knife sheath. So decide for yourself.
How To Care for a sheath - there are literally thousands of ideas floating around out there but the following are ones I've tested under all kinds of conditions and they work for me - so take it for what it's worth.
A lot depends on how much one is used but also in HOW it is used. For a Hunting/Camping sheath - Mut's advise is pretty good. The main difference is I would suggest CLEANING the sheath intermittently before reconditioning. Like Mut I also seal the interior of my sheaths and this way you can rinse them out with clean water. Blow out the excess with Canned Air or a LOW air pressure - hang upside down and let AIR dry. You can reseal if necessary by pouring a small amount of the original sealer in and draining thoroughly. I then clean the outside with a good saddle soap - follow the directions. Apply a good top coat - for a heavy using sheath I like Mt PitchBlend or Obenauf's. Apply a couple of LIGHT coats (it's like drinking - a little is nice - too much and well
).
For light use sheaths I would clean/condition maybe twice a year. For light use I usually recommend Lexol Conditioner or Fiebings 4-Way Leather Care - a heavy conditioner just isn't necessary and these will not normally rub off on clothes like the heavier duty finishes can.
Bottomline - There are many, many other leather care products such as Skidmore's Leather Cream, Leather Amore, and Leather Nu - try them and see what you think. The ones I use have been tested by myself and others in some of the most extreme environments/conditions on this earth and I know they work so that's why I use them.
Well it seems like I've once again followed my own advise - why use one word when ten will do
- but I hope the information is helpful to some of you any way.