The Marine in the image is using a carbide lamp, that was originally used by miners, and adopted by shooters. I recall smoke pots (ugly black spheres that I think were originally designed for road workers to mark construction areas) on the ranges at Camp Matthews, Camp Elliott, and Camp Pendleton for blackening the front sight. I never used the smoke pots and I assume had kerosene in them. I acquired a carbide lamp and a can of carbide but never used it. Did on occasion use the canned spray product. Had to be careful of the canned spray as it could build up and change the sight zero. The carbide was cleaner and as far as I recall didn't build up on the sight.