Originally Posted by
unterhausen
I'm not sure of the exact composition that causes rust either. 753 was 531 with better marketing. Okay, it was heat treated. 531 had what looked to be a phosphorus treatment. You can tell because it's a dark green. Nowadays everything is silver, so no treatment. I have never heard anyone mention this about 531, but you can tell it on sight. I don't think it's mill scale. At Trek in the '70s, every frame went through 7 dip tanks and the frames could sit around forever in high humidity and not rust. I think there was some phosphorus in a couple of the tanks. If you look at the initial Trek brochures in the background of the picture of the two bearded guys (Dick Nolan and Mike Appel) there were racks of frames that they never sold. I never knew why, they probably should have scrapped them. But they didn't rust.
I have a frame made of reissue Columbus SL and the surface rust on that is pretty striking. Don't think I have ever had a bike rust like that before.
I have seen very occasionnally some rusty frames with Reynolds 531 ,almost none with 753,731,708 classic and 653. With I have seen many rusty SL, SLX, TSX, Thron and Brain frames. Cyclex being inferior to Nivacrom and Thermacrom,I am not astonished about that they rust faster.With Excell tubing never seen one being rusty. The 7 dip tanks was perphaps inspired about how chrysler corporation were rustproofing the chassis of their cars as well as the bodyframes of their cars back in the 60's-70's.