I've got some leather boots that are showing some wear and tear. More importantly, the seam between the sole and boot is starting to crack and allow some water in. Do products like ShoeGoo or FreeSole work well to extend the life of boots when used preventively, both on the sole seam or the toe box? Are there any treatments I should be putting on the leather itself to minimize the risk of cracking?
The first commandment of leather care is to never let your boots dry too quickly, for example on direct sun or next to a source of heat. The leather could crack or shrink. You have to let them dry slowly.
Second, you should use something to keep the leather in good shape. There are tons of products for this, so pick a dependable outdoors brand and use what they have. (I use a silicone-based cream by Scarpa, but that's probably not available on your continent :-) Some people use various regular greases from hand creams to edible oils. I would not do that, as picking the wrong substance may get your leather too soft or compromise the waterproof membrane (if you have one). The sole purpose of this treatment is to keep the leather happy, ie. not dry and reasonably soft.
Third there is waterproofing, where we enter a world of alchemy in which everybody claims that something else works for them :-) Some products take care both of leather conditioning and waterproofing, some products only do either. Choosing the right waterproofing product depends on whether your boots have a membrane and whether it still works. If the membrane is there and works, you can mostly forget about waterproofing. Some extra waterproofing should improve the boot breathability when wet, so it makes sense, but it has to be a product intended for leather boots with a membrane. Otherwise it could clog the membrane or something like that.
If there is no membrane or it leaks, there's again a lot of solutions to pick from, ranging from various sprays to waxes. The waxes are very dependable, meaning a well waxed leather will not let the water in for a long time, but some people say that wax limits the breathability and makes the leather harder, which can lead to cracking. I have no experience with wax, since my membrane still works. And speaking of wax, it's good to know that once you wax the leather, there's pretty much no way back.
From the amount of what I have written it looks like I know something about it, but that's not really true, so I'd welcome other opinions and corrections.
I recommend you bring your shoes to a professional shoemaker / cobbler. The issue you are describing in where your seams crack sounds what I have had multiple times in the past, and my shoes were easily fixed by a professional back then. Personally I would recommend against trying to fix this yourself, unless you have the experience and tools to do so the right way.
What a professional shoemaker / cobbler can do:
- re-sew seams
- re-apply glue to fix loose glue-seams or soles
- re-sole your shoe, giving you a new sole with a fresh, intact profile to improve grip
What you can do yourself: tend to the surface of the shoe, i.e. clean and impregnate the leather. There is an entire question on this already: Impregnation and waxing full leather shoes
I have had an old pair of work boots do this, I used shoe goo [what I happened to have] and they lasted months longer, I am less sure if I would trust it for a hiking boot. It will depend on what kind of terrain weather and distance you normally go.
If you mostly hike in good weather, easy trails and less than a few hours long, sure go for it, worst comes to worse you get an embarrassing walk back to your car, if you are mountaineering, multi day backpacking, or even on a rough trail with sharp rocks, I would be much less trusting of these repairs.
A good cobbler, IF you can find one, would be a good option if there nice boots, with cheaper I would self repair or just replace them.
As far as leather treatments, I have used snow-seal, but apparently it can cause your boot to dry wrong? I have since switched to mink oil, have not had any problems with it yet, I apply a coating between once and three times a year depending on how hard I have been using my foot were. make sure you follow the directions [clean/dry boot, good ventilation etc.]. I am told if you use to much treatment, or treat them to often in can soften the leather causing its own issues, this has not yet happened to me.