Most of the "Walking Out"/ dress frogs I have on my KS98s are made of this type of leather. The patent leather like finish dries out pretty much over time even without much of a heat source present, but will definitely be worse if kept in higher heat conditions. The leather can take on the impression of items in contact with it. Mostly the diamond shapes from the grip plate of the KS98 will be observed. I have one that was stored on top of a shirt or uniform and has a button impression. The top layer can also peel off, sticking to a grip and resemble black paint or tar. You can not do anything to "revitalize" the leather. The best you can do is try to keep it in a controlled environment. Low humidity, but not desert dry. No dust or smoke. I was told by a caretaker at a museum that in another fifty to seventy years or so, most of the leather frogs such as these will have deteriorated to not much more than the rivets.