Quote Originally Posted by BigBear View Post
[Pressure Washer] Did not work, even with mixed chemical paste beforehand...
Might depend on the pressure washer.

I tried one of the "homeowner models" to strip paint off my gutters, outside clapboards, and concrete floor....nothing happened---it was worthless.

My neighbor loaned me his gasoline powered model.

Took the paint off my clapboards and stripped the paint off the galvanized gutters (down to the metal), with just water.
I had to be careful, as at first, with the "jet" nozzle. It put a hole through my fascia board, just below the gutter, until I learned how to use it better.
This was from about an 8' distance.

It took EVERYTHING off my garage floor with just water using the "fan" nozzle. It was literally like using a paint scraper to lift off the oil, grease, paint, etc.

While I can't guarantee it will work on your problem, I can say that my success depended on what kind of pressure washer I used.