Today, I received one gallon of Mastercoat metal prep and rust remover. Since my compressor is down for a pressure switch I turned my attention to the roof of my 66 coupe. Originally, this coupe came with a vinyl top from the factory. When it was removed I believe there was no prep of the metal before the roof was painted. The rust is terrible. I also purchased a chamois and a spray bottle. After filling the spray bottle I wiped the area off with thinner to remove any residual contaminants. I then soaked the chamois in a can of rust remover, sprayed a small area and applied the chamois soaked with the rust remover. I let it sit for 30 minutes, removed and took my grinder with a stiff wire wheel to the roof. The rust started disappearing. I then laid the chamois back on the area I cleaned for another 30 minutes. Keeping the area wet. I removed the chamois and wire brushed and sprayed the area to keep it wet.
You can see the difference in the photos. The pitted areas the rust has lifted out or is lifting out. As per the instructions, once the area is clean, wet the surface area and with a clean cloth wipe dry immediately. After it is dry a zinc phosphate coating will form over the surface in a grey haze. If no grey haze repeat the procedure. I attached a few before and after photos. So far, I'm pretty happy with the results. Mastercoat can be found at the following link:
http://www.masterseriescoatings.com/index/Jeff