My son-in-law wipes the out side of the cap and nipple with a little wax from a toilet seal. The people who used muzzle loaders when there was nothing else, often wiped the area with either bee's wax or bear grease. A very good tight fitting cap is almost weather pruf. With a little wax or grease is should be very good. I have had the most problems when using musket caps. They did not fit as tight on the nipple. I carry two capers in dry pockets. One is very reachable. I also carry a extra tin of them in my belt pouch.