I had been using pre-mixed joint compound, but I ran out just before I was finished, and my neighbor (who had just re-done his basement) gave me some Sheetrock Easy Sand 90 Joint Compound, and his drill bit /paint stirrer so I could mix small batches.
Unfortunately, I missed cleaning the paint stirrer when doing my cleanup, and didn't remember it until a couple of hours later, when I was in class. When I got home, I gave it a soak, and have scraped / scrubbed as much as I can off, but there's still quite a bit stuck on it in difficult to reach places.
Is there anything that might soften it? (eg, a strong base? I have Barkeeper's Friend, lye water, and lye crystals), or do I need to stick with mechanical means? (I have some brass brushes if I can remember where I put them)