Care of Walking Boots
Leather has three enemies and in ascending order of threat they are Acid, Drying Out and The Owner! Much walking in this country is on wet upland acid soils and so wash off all dirt at the end of each day. Leather is skin and your boots need to be treated in rather the same way that a woman looks after hers. Walking through wet grass puts your boots through a continuous car-wash which is a very efficient way of removing the natural oils from leather. Cracking, shrinking, stiffening and greater porosity will follow and the adhesives employed to fix on the sole will fail in the end.
A saddlery shop will supply saddle soap, leather preservative like Hydrolan (a moisturiser) and rejuvenator like Gold Label. A very thorough wash with saddle soap about twice a year will neutralise acids. Set about such a maintenance session when you know you will not need your boots for some days to come so as to get as much preservative into the leather as it will take. Remove the laces and clean the boots first then scrub with a stiff brush, saddle soap and water; rinse off and repeat with very little water so as to produce a thick soapy foam. Do not rinse but allow to dry naturally with the mildly alkaline soap residue remaining on the leather.
Once dry, brush off the dried soap thoroughly and soak the leather again to open its pores and allow the preservative to sink in rapidly putting back what the long distance path takes out. Be generous with this treatment using your fingers to rub it in and paying particular attention to the toe and to the part just at the bottom of the laced portion where the boot flexes most. You will see the preservative disappear quicker in these places so go back and put more on. Leave for a couple of days so that it soaks in - remarkably such materials will not waterproof leather so now comes the final treatment.
I have relied on Nikwax for thirty years. The original type, worked in with the fingers has exactly the tenacity to resist the "Car-Wash" effect for days on end. Nikwax will soak in to a small degree and on a long trip is worth taking with you to sustain the protection on the toes, across the part which flexes and along the seams particularly where the gusseted, laced part is stitched to the upper.
Leather/ fabric combination boots
Goretex and its imitators are sandwiches of an outer such as leather or woven nylon with a lining. Between these is a membrane of expanded Teflon which has pores so microscopically small that only water molecules can pass through. So the vapour from your hot feet will be driven through while the water droplets cannot penetrate from outside.
To ensure water continues to form beads on the outside you must proof the surface much as you would polish a car this goes for many breathable jackets as well! A purpose made spray waterproofer by Nikwax or one of the outdoor proofing manufacturers will do the trick. Remember the car-wash effect and keep it proofed. Remember the Acid and keep it clean and the leather parts moisturised as well. If the effect of Hydrolan on suede or nubuck offends you go back to the Nikwax display and find the purpose made product for that application. Follow these regimes and your boots principal enemy will be vanquished.
OK, so you didnt do any of this and your boots are showing signs of cracking, what to do? Now reach for the rejuvenator. Riders know that if leather cracks the reins can break or the girth strap give way. At a gallop that can cost you your life so the stuff they use is heavy duty indeed. I use Elico Gold Label Leather Rejuvenator. It looks like a cross between runny honey and axle grease (no, I havent tasted it!) and it works miracles on dry, hard, cracked leather. Always, always clean the leather first with water and use the saddle soap treatment to make sure the acid is neutralised. This will also start the softening. Apply the rejuvenator according to the instructions on the tub. If necessary, repeat. See also www.nikwax.co.uk and www.gore-tex.co.uk