Sno Seal waterproofs leather products. The beeswax formula is long lasting, doesn’t harm or weaken leather like animal fat waterproofing products do, and still allows the leather to breath. Easily applied by heating your leather boots with a hair dryer and simply rubbing Sno-Seal into the leather.
I haven’t seen or used another product as good. I’ve been using it for the last tens years on the four pairs of prospector Gortex/leather boots that I’ve owned. Because of the Sno-Seal I wear out the soles (multiple times) before the leather shows any kind of deterioration.
A 3 1/2 oz. (100g) tub of the stuff will last me two years for one pair of boots, reapplying every three to four months, depending on use.
[Please see the more recently-reviewed Nikwax Aqueous Wax.]