Cleaning Hot Rolled Steel for priming and painting

[Big Paulie]

Looking for the best way to prep my HR pieces prior to painting. Someo fthe projects are using angle iron and less than 6' in length. One way to prp HR is to remove mill scale with muriatic acid, brish, rinse with baking soda (to neutralize asid residue), then prime before painting.

This is usually a hassle after assembly, and a bit of a dangerous mess. My thought was to get some lengths of 6" diameter PVC or CPVC seawar Pipe, cap one end , and use as a vessal to hold the individual pieces of angle iron / tubing that are cut to dimension, in a bath of muriatic acid. This way, if the piece is slightly longer, I could soak half, then rotate. An alternative to the vertical bath could be to slice the pipe lengthwize into troughs, and lay the pieces in them. I like the vertical method, as it takes less floor space, and is safer with kids and pets wandering around.

Place in bucket and brush down, then resoak until all clean. Dip in baking soda solution and rinse/ dry / prime. Baking soda is required, to keep the pieces from rusting immediately after rinsing.

when assembly prior to welding, just grind off the edges to be welded (would do that anyway), or use weld through primer (never tried that).

Reprime the welded area after brushing, and it should be fine until assembly is done, and a final paint is then done.

Anyone have a better method?

[geezer]

For angle iron projects I just use rust paint ,,,no primer,,cause primer just makes a skin for the rust paint to float on and it scratches and shows easily,,,where as the rust paint by it self goes into the mill scale and sticks like S##T to a blanket..It all boils down to how much time and effort you want to put into painting some thing like that,,

[rake]

Big Paulie a chemist friend of mine told me that sodium bicarb doesn't do a good job of neutralizing muriatic
acid. Arm and Hammer Washing Soda does a much better job. A stronger alkaline. He said that even after
a sodium bicarb bath that I was actually leaving acid on the surface and trapping it under the paint. Paint
seemed to come out better after switching.

Removing mill scale is a beotch. whether grinding, blasting or dipping.

When I was at the shipyard they had a vibrating media tumbler big enough to get an M1 tank in.
Now that was an easy way! Supersize a bullet tumbler?

[Poptm]

leave it outside in the weather and let it rust off. Then clean off the rust. Seriously, it's one way to do it. If you don't like that just paint over the mill scale.