I just tried GlenKaren for the first time-- to see if something could be done on some salt stains on black oxfords. A few years back, I'd walked over pavement that was getting some spring rain after a rather toxic winter. No harm, I thought, but then there appeared a few smears of white stain when it dried. I tried myself to use vinegar and water, then black polish. Not great, but perhaps OK for non-special wear. Then I had them in London and got stuck in a real rainstorm. I let them dry for a few days, and when the problem re-emerged, I decided to return them to the maker to see what they might recommend to really fix the problem. A month or so later I got them back. Lots of wax polish, but still an obvious scar and white film around the salt/water damage.
I tried a few things again myself, including some Saphir Renovateur and black shoe cream. No dice, and I was prepared to retire this pair after a mere 8 years. Then I tried GlenKaren.
Whoooee! First, I used acetone to get rid of any excess polish. I know-- only in last resorts. But I was desperate. Then the GlenKaren conditioner. The acetone didn't seem to have removed much polish, but the rag was thoroughly black after running that neutral cream over the shoes. These guys were thirsty, and took quite a lot. I let everything dry overnight, and then used the black/bentonite cream. The result now is that for the first time in a few years, the shoes are black. And rather attractive. If you catch the light just the right way you can still tell that there is a tad of water damage under the black, but the shoes have new life, and are now worth getting re-soled.
I've used the conditioner on a few other pairs, and have been struck by how much the leather changes its appearance. More plump, less glossy (a small casualty, perhaps), but much softer and springier. On a brown pair that had sort of a "willow grain" finish, the surface nearly smoothed out as much as regular calf, although it's coming back to the previous finish now that it has had a chance to soak in and dry over several days. The dark brown color is fantastic now even without other polish-- better even than what a famous polisher/blogger had left on them last year.
Anyway-- great stuff. I don't know if I will retire Saphir and some of the other good polishes, but this is a great addition to the kit.