I have an anecdote about Dumonde Tech:
The stuff is supposed to "bond" and/or "plate" metal parts - that's
it's key "tech", I think. In use it acts like smelly oil, but does
seem to last better than, say, motor oil.
I noticed that if I took a dirty chain off and let it soak in mineral
spirits for more than a part of a day, the gunky lube turned kind of
plasticky and wouldn't brush off; whereas if I took a dirty chain off,
soaked for a few hours, and then scrubbed, ti would come up shiny
clean.
Last week I had two chains to clean - one just off the bike, the other
had been sitting coiled in the garage for a couple of weeks. Soaked
them together for a few hours, and scrubbed them both. The one fresh
off the bike came up shiny clean; the one that had been sitting didn't
(still kind of greasy w/ plasticky residue).
But I put the still smeary chain on the bike, since it was the older
in rotation, and applied fresh lube as usual since the scrubbing had
at least cleared the crusty stuff off the outside.
This chain ran a couple of hours in the rain, and still doesn't need
re-lubed. It's like maybe the smeary residue acts like sticky waxy
grease to seal a little better, maybe.
The phenomenon of a chain sitting (either in air or mineral spirits)
turning plasticky is interesting. It's like as long as the chain is
being run on the bike every day the lube stays solvent. I may have to
try cleaning chains shiny clean, then putting them on a bike w/ clean
sprockets to lube, wiping the outside, then hanging them up for later
use. (As it is I have been hanging them clean and dry and lubing when
installing to ride.)