Marvelux has one very good use. I hate to mention this since others will now know and I'll not be able to get free Marvelux. I mix one hundred forty pounds (4700 200+ grain .308 and .30-'06 bullets) of used linotype hard alloy in a cast iron pot each Fall to have homogenous alloy for the coming year. May be overkill, but Alice likes to shoot both CBA Production and Military Rifle which require a hard alloy.
Marvelux works very well to get all the crud out of the mixture that sits in the pot as we begin. First, I run it on a hot plate to drive the moisture out before we begin, less bubbling. The other trick is to use it very sparingly as a light dusting and stir into the alloy. Every time I see someone offering free Marvelux at a match, I get it.