I found this spray product through an ad here. Got a bottle to try and never got to really use it until now. I stripped my 66 with Removall, and then used this with a bristle brush, starting at the bottom and working up according to directions.
It was easy and not very caustic in smell. I did wear eye protection and gloves though.
Once it reached the higher parts, I let it sit a few minutes then hosed it off.
The skin looked a lot better, shinier and clean. I now move on to some polishing.
This is a mild acid, and though it etches, it is not very strong like other acid washes. Wished it remove filiform but of course that will take manual labor.