Okay, I've asked a bit about this before, but I've got a couple new questions.
I've got some internal frame rust, and it's kind of crusty in there. I don't think it's structural yet, and I'll find out for sure, but I want to prevent it from worsening. The first problem I have is that there's some paint on the inside of the tubes. I can't reach in there and remove it, so I'm thinking maybe I should dip the frame in paint stripper, but I don't know if that'll remove it thoroughly enough. I then want to use some sort of acid to convert the rust to an inert compound. I also heard that some of these acids will make the frame MORE prone to rust in the future, so I want to avoid those. Someone mentioned "acid dipping", which I'm trying to find out more about, because he mentioned it'd remove paint as well. He said that professional places will do that.
So yeah, if you know any specific products and tips on application, that'd be great. I'm looking to get this done as cheaply as possible, of course. Once all's said and done I plan to framesaver it and paint it.
You could take the frame down to a local sand blasting shop and see if they can glass bead blast the rust off or use crushed glass (cheaper). The cost would be about the same as buying the chemicals of your choice.
In any case, The cheap way: you would need a Tube (Twisted-in-Wire) Brush and a long wood rod to secure the brush to (screws and plastic ties) so you can reach deep in the tube to scrub off the majority of the rust. Use white vinegar (slightly acidic and inexpensive) with the brush to remove the rust. Rinse with water, dry (can use a hair dryer), inspect, and repeat as necessary. Once you are satisfied the rust is removed, apply your frame saver spray or CVC Galvanizing Spray (Zinc Coating Spray - find it at your local auto parts store) and you are done. BTW, there are round sponges (can cut to size if they are too big or cut a square sponge) that are available at any store or art store and you can use that are either strapped to or screwed in in middle (use a couple of washers - front and back) of your wood rod to apply or evenly coat the inner tubing surfaces (esp at the bottom of the tubing) with your frame saver spray.
Why do you say tube? There's rust in all of my tubes as far as I can tell. I put my finger into any given tube and there's rust in there. I don't understand how the wire brush would make it into all the tubes. I like the idea of bead blasting if that'll get into the inside well enough. Otherwise I think I'll just dip it into chemicals. The only problem I see is that they don't mention removing paint, and the first won't remove paint at all. Most of the tubes on the inside are unpainted, but there is paint leaked into them, so I'd need to remove that first before doing the chemicals. That makes sandblasting sound really good.
If the rust is not structural, just framesaver it really good and ride. If the frame is stripped down for painting, you can have it sandblasted - inside included. A good phosphate solution is also a good way to go - it removes the surface rust and converts the remaining rust to iron phosphate. Home Depot sells phosphate solutions in the form of Behr Concrete Cleaner and Degreaser. This product is a favorate of people restoring old motorcycles and removing rust from the inside of the gas tanks. http://www.homedepot.com/prel80/HDUS...gmj.0&MID=9876
Becareful buying/selling bike parts on-line. I learned the hard way. :(
a fella i used to work with has a 1948 frame made from reynolds tubing. he's used it year in year out, sleet rain and snow, all mixed up with the salt they throw on the roads here. and whilst i don't doubt that there is rust inside it, it has yet to become a problem.
Yes, I know it goes both ways, but there was a thread a while back about whether people knew someone who had a frame fail due to internal rust, and quite a few did know someone first hand. I'd really rather pay the $20 or whatever to ensure this lasts a long time.