My First Soak. Thoughts?

Well, after 30 years I tried to clean my first coin.

Reviewing advice and experience from members I started with a circulated coin that isn't in great condition and even if it was it's not worth much. And it had pretty cruddy surfaces. According to Numista the coin is aluminum bronze.

I couldn't really tell from looking at the coin what sort of crud it might be so I thought I'd start slow and see what happened.

I followed the polarity ladder by first soaking in distilled water - dry - and then a half hour soak in acetone. The picture below shows before (top) and after pictures. They almost look backwards to me. As you can see the results weren't dramatic.

I've read a number of posts about others experiences. I have an idea what verdigris and PVC damage look like from others posts. Still it's not always obvious to me.

This coin had a kind of blackish gunk on it. I suppose it's just having seen lots of coins with various kinds of gunk to have an idea what you might be dealing with and what might work best. It seems to me that both the coins composition and how long the gunk has been there can impact what it looks like. Is there a better approach to recognizing the gunk and choosing the best method of dealing with it?