Evapo-rust dried up into weird “cake”

[Dave Rosner]

I’ve been doing my spring shop cleaning of all my old hand tools. I have a small pot of evapo-rust that I’ve been dunking screws and small parts in. I had a bunch the other day that I left to soak overnight. Next day I can’t explain it but all the liquid dried up into a rocky dirt like cake type matter. Seriously it was weird and it is taking a lot to clean off the parts now. It’s kinda soft in that I can crumble the free matter but whatever it is that is stuck to the parts takes a stiff screw driver to remove.

anyone ever seen this cleaning old rusty parts?

[Mike Henderson]

Never seen that. However, I usually cover the container when I'm soaking something in EvapoRust. When I pour it back into the container I add water to fill it up.

I'll be interested to hear what others have to say about your 'cake".

Mike