Cleaning and painting rusty steel frame
10-26-19, 08:04 AM
#51
Junior Member
Thread Starter
Here are some pictures after BB extraction, looks pretty rusty down there.
What can be seen is some white paint there, I am completely sure it's manufacturer paint. Not sure what to do about it, should I just leave it and wash internal tubes with acid? Because I could also try to scratch those most accessible areas and paint them with zinc primer paint. If so, I guess I should take special care of BB threads(by screwing old BB cup in?).
What can be seen is some white paint there, I am completely sure it's manufacturer paint. Not sure what to do about it, should I just leave it and wash internal tubes with acid? Because I could also try to scratch those most accessible areas and paint them with zinc primer paint. If so, I guess I should take special care of BB threads(by screwing old BB cup in?).
11-11-19, 06:57 AM
#52
Junior Member
Thread Starter
Sadly I had no time to work with frame until now. I have filled frame internals with ~20% phosphoric acid, there are few micro leaks but I am just collecting acid droplets and filling frame again. The leaks are like half pint per 12h total. I am going to pickle it for around 48h total.
The thing is, there's lot of residue going outside. Somehow droplets got out and whole frame external is mildly covered with acid that turned into white residue. Additionally, some really rusty internals produced massive amounts of black residue(ferric oxide I guess) albeit, it's very slimy and also got out of frame and hardened on the outside. As for interior I guess it's very good and exactly how should it happen.
But the problem is, I have to prep frame for external painting and for this I need it to be very clean because the company I bought paint from did not recommend acid pickling. I am not sure what to do because phosphoric acid is a chemical and might react. And I will have to remove it obviously. Should I try to neutralize it with baking/caustic soda? I have heard that caustic soda will dissolve zinc and the paint I got is zinc phosphate based. For just abrasive methods I have working drill with few different wire brushes, steel wool and 60-180 grit dry sandpaper and 1500-2000 grit wet sandpaper.
I was thinking about using power tool to remove the hardened residue then spraying frame with some very mild caustic soda/tap water solution to neutralize the acid on the exteriors(I could also wet-sand with caustic soda/tap water) then power-tooling it again with wire brush and finally using acetone to sanitize it right before paint. Would this work?
The thing is, there's lot of residue going outside. Somehow droplets got out and whole frame external is mildly covered with acid that turned into white residue. Additionally, some really rusty internals produced massive amounts of black residue(ferric oxide I guess) albeit, it's very slimy and also got out of frame and hardened on the outside. As for interior I guess it's very good and exactly how should it happen.
But the problem is, I have to prep frame for external painting and for this I need it to be very clean because the company I bought paint from did not recommend acid pickling. I am not sure what to do because phosphoric acid is a chemical and might react. And I will have to remove it obviously. Should I try to neutralize it with baking/caustic soda? I have heard that caustic soda will dissolve zinc and the paint I got is zinc phosphate based. For just abrasive methods I have working drill with few different wire brushes, steel wool and 60-180 grit dry sandpaper and 1500-2000 grit wet sandpaper.
I was thinking about using power tool to remove the hardened residue then spraying frame with some very mild caustic soda/tap water solution to neutralize the acid on the exteriors(I could also wet-sand with caustic soda/tap water) then power-tooling it again with wire brush and finally using acetone to sanitize it right before paint. Would this work?
