OldBaldGuy: You're right. Spit-shining is pretty much long gone. And I too noticed that there was a difference after using wax that had been melted and then allowed to cool. I used to do it though, on new boots and low-quarter shoes, to get the first few coats on there.

Frankie: I really think it might be overkill but I don;t think it would hurt. Not right after you loaded leather with wax, but as an occasional "water-proofer", the Nikwax would work. I think, for me, Id just go with one or the other. One thing I might do is use snoseal or nikwax along the sewn seams, especially where the uppers are sewn to the sole.

As far as overboots that's the way to go if you know you'll be sloshing through ankle-deep water. No matter what you put on leather, water will still get into the pores and get the interior damp. I mean, if you were to somehow seal leather completely, I think it would, like wood, just expand, crack, and you'd be back to square one. Waxes, preservants, softeners, balms, "water-proofers", I think the best they can do is help make them water "resistant".

Kiwi do a wetpruf polish too.
The Sock

For field use, I gently warm up my boots and coat them in dubbin, as the dubbin melts it soaks into the leather, do that a few times until the leather wont take any more and your feet are dry and toasty for ages. Upkeep is easy, brush off any mud and reproof. A layer of polish makes them nice and black and keeps the grown ups off my back.

For general use, Kiwi black all the way. On, off and finished with a soft duster.

Parades, two or three days work spit shining or bulling. Starting off with burning the old polish off, melting beeswax into the leather and smoothing it with a hot spoon. Followed by the calming actions of little circles with polish and water on a sylvit cloth. I never use spit, god knows what may fly out of my mouth and scratch the finish. All finished off with a cotton wool session under a running tap.

Treated leather is far more waterproof and resistant to wear and rot. During the rainy season I have seen new boots left untreated fail at the junction of sole to upper because of rot in two months.

Kiwi wax is okay for smooth leather. For a time I used Snow Seal. It is okay for smooth leather and cold weather use. A hair drier to warm the leather and it melts right in. The down side is that soaked in the leather becomes pretty much impermeable. Waterproof but it doesn't breath much and it has to be reapplied regularly.

Then I moved south and the ability of the boot to breath became more important.

More recently I have shifted to silicone. I got a quart of the stuff and apply it with a foam brush. When boots are new I lay on a heavy coat and recoat every few weeks for a while. Don't put too much on all at once as it can weaken glues. It will also make blond rubber darker amber and a bit harder. Seems to make the rubber less adhesive but wear longer. An acceptable trade-off in my book. After a few times the leather becomes pretty much waterproof and won't rot. After that point I might add more once a year or so.