My first attempt with a rust converter has not gone too well. Tried it on my truck, first, just to see how it works. Bought the Rustoleum kind in an 8 oz. bottle -- brush on. It's white and water based. Some of the deep rust turned sort of black after quite a while, but nothing in the 15 minutes mentioned. It will rub off with a finger tip when applied over paint. Does temperature have an effect on this stuff? It was about 55 degrees or so. Since it was coming off easily, I sanded a bunch of it, and the red rust was still there under it. Should I try a different product, or did I just do a bad job of applying the stuff?

When I used it, it seemed to me that the rust converter had to really mix well with the rust - i.e. thicker layers of rust will not get the converter in contact with anything but the surface stuff. Add to that the fact that it tends to form a black primer substance, and it becomes even more difficult for the liquid to get in contact with deeper rust.

You should probably remove most of the deeper rust before applying the converter - it works really well on surface rust.

I bought some spray stuff from wallymart. The instructions say to remove as much rust as possible, then apply. I think the stuff is solvent based. I have had great luck with it, but be sure to let it dry / cure before you do anything else to it. I have never used the water based stuff. Guys I work with just buy the Rustoleum primer or paint, which contains the converter.

I agree with Dash, that the converter is not penetrating the rust.


Tom

Thanks for your replies. I did sand the areas pretty well, I think. This area on the frame was mostly surface rust, but I sanded it pretty thorougly, anyway. Some parts of that turned black in the seams, but the flat area didn't, and the red rust was still there after it dried a couple of days, and I sanded the white stuff off. Another area, a battery tray with some pretty healthy rust, I mostly scraped with a putty knife and sanded some, but a good bit of the coarse rust did turn black. I think I'll try some other, maybe solvent based, brand. Especially when I use it on a bike.

I think that might do the trick for you. I just used some, can't remember if it's Rustoleum or Locktite brand, but definitely solvent based. Used it on the bed of my truck. Says it needs some rust left on to work. Turned the whole area I painted it on black and seems to have worked well. Also, I remember the can said it will actually rust areas of bare metal and won't work on any painted areas. FWIW.

Was the "white stuff" in the battery tray? If so, then you should make a paste out of baking soda and water, then apply to the area. Let it react with the acid, rinse and if there is still white, re-apply. Then rinse and dry the area off.

Tom

Yes, temperature does affect the reaction, but leaving it on longer should compensate for lower temperature.

Hey, the white stuff is just the product itself, after it dried without interacting with the rust. I've been reading some history posts, and apparently this is the kind of thing that Ospho is supposed to do. I'm thinking of trying that next, since I have a bottle of it. But I've sort of been blaming the Ospho for the advanced rust on my truck in the first place. I had bought the stuff a few years back to use on an old Mustang that we didn't keep very long. Then, three years ago, I hit the second deer going to work in my truck. I needed to get it back together over the weekend, and came up with junkyard parts just as the junkyard was closing on Sat. I realized the radiator support had a rusted through place and figured I had to use it because of time, but pretty much coated the piece in the Ospho. I didn't paint over it or anything. I didn't put a grill back in it since I bought a new aftermarket rad. support and have been waiting for a chance to tear it back apart. The radiator support has been looking rustier every time I looked at it ever since. I think maybe you have to paint over the Ospho, or neutralize it, or the acid will promote further rust. I've gone ahead and primered the frame section and battery tray, since they are both thick steel in the first place. Waiting for warmer weather to paint it so I can put it back together. Really want to know how to do this for the steel rims on a bike project, though.

I recently used the water base stuff on the underside of two fenders. One fender was near a heater and was just warm to the touch. The other was at the other end of the work bench and cold. The ambient air temp was about 50 degrees. The warm fender turned black in about 15 minutes. The cold fender still has a white milky look. I think the temp is an important factor. The directions said that it needs to be above ??? temp, which I can't remember at the moment. Apparently, they mean it!

Yes, you must paint over Ospho, and any brand of rust converter. They do not provide [I]any[I] protection to the metal, only to convert existing iron oxide (rust) to iron phosphate or magnetite, respectively.

I work on ships and we have, as you might imagine, quite a lot of rust/paint problems, so I'm always interested in different approaches and results.

In my experience Ospho works very well and rust converter is more situation dependent. Neither Oshpo or Rust Converter (I would recommend Corroseal brand, widely used on ships) will work if the scale has not been removed.

Ospho is not as temperature dependent, but does work much faster when exposed to sunlight.

As for steel rims, I've been contemplating this as well for some old 28" Westwoods. I think I'm going to go for the Ospho. It will produce a sort of white film when dry where it has converted rust. You can wipe this away with some solvent and call it good. That is what I'm going to do.