On Sat, 19 Sep 2015 10:18:18 -0400, Ed Huntress
wrote:

On Fri, 18 Sep 2015 21:00:50 -0500, Tim Wescott
wrote:

On Fri, 18 Sep 2015 18:07:54 -0500, Lloyd E. Sponenburgh wrote:

fired this volley in
:

What could cause this grease to do what it did?

Soap. Most 'greases' are suspensions of an oil in a soap. Once the oil
has evaporated or been expelled by heat, the soap congeals and finally
dries and hardens.

And soap is NOT soluble in mineral spirits. Water would likely have
cleaned it up faster.

Caviat: this is based on theory, not experience.

It may not be too late. Try soaking in hot water, or even boiling it. A
bit of dishwashing detergent in the mix might cut through any solvents
left in there.

The"soap" used in greases is metallic soap. It is not what we
generally think of as "soap" and it doesn't behave like soaps we use
in other contexts. Typically it is made from metal compounds reacted
with acid, not with fats reacted with alkali, like the soaps we're
familiar with, and it isn't generally water soluble.

There are several metal soaps used in greases and they behave
differently, but they're all difficult to dissolve. Some, like lithium
soap, are slightly soluble in water. Most are not.

They aren't soluble in most common solvents, either. You can try
propylene glycol or even antifreeze and see if it works. It will
chemically attack a few of the metallic soaps.

Otherwise, I have had success in the past using gasoline to dissolve
the gunk from ancient lithium grease (white grease). Maybe it depends
on how hard the grease has become, and how much petroleum-based oil
still remains in it. I suspect, but don't know, that I had success
with that because there was enough oil left in it to take the soap
with it when the oil was diluted with the gasoline.
The strange thing about this grease is that it did not dry out like
the old grease did. It instead turned into very sticky paste. There
was no evidence of free oil like I have seen many times when grease
starts to break down.
Eric