Frog lube isn't petroleum or mineral based. It's something that's organic. I don't think it's water soluble, and from what I've seen it's done a pretty good job at inhibiting rust, at least over the last 4 or 5 years, on all my mosin's. I don't have any special desiccants in my safe, which is down the basement, and the humidity is roughly 35% or so. I also know that the weapons wick FL after repeated firing and heating up. Also, there's actually a tempering process you have to go through, to remove all petroleum based lubes off your weapons before you can convert it to Frog Lube.
The only reason I converted is because my work bench is in my basement and isn't ventilated all that well. And after the "Hoppe's incident", when I thought I was having a heart attack, I made the conversion. Personally, I like the stuff, except for the cost. BUT, it's not an inhalation hazard or poisonous.
Found out something else earlier... today I noticed that I seem to be going through it a little faster than I'd noticed. I come home from work and notice the faint fragrance of Frog Lube in the air and was curious. The wife doesn't want to have anything to do with guns, we have 3 cats and no kids. So I ask the obvious question, when did the cats start eating my gun cleaning supplies... The response I get is "Oh I was reading where it's really good for my skin <rant> you mean you didn't notice my silky soft hands?!? </rant>
My reply was get your own damn frog lube, or I'll tell your friends you use my gun cleaner on your skin. Wrong move on my point but I think she understands now.
I recently sold my Glock G42 to a very nice young lady who was taking to a Gun & A Girl Meet. I have been cleaning and lubing it with FrogLube, but did not see any necessity to tell her. I am sure she has her favorite CLP product