Pickling some steel

[bucky]

I’m in the process of fabricating a rack to hold 2 fuel jugs on the tongue of my teardrop trailer. My steel is rust free but I’ll need to remove the mill scale for painting. It’s a pain to grind/sand it off. Anyone pickled at home? Longest piece of steel angle will be 22” so nothing long. I have muriatic pool acid will this work? How much should I dilute it?
Design is similar to the picture below except I will run 1” angle iron risers on the corners connected to strap steel for the horizontal part. I’m using steel I have laying around at the shop so that dictates the design.

 

[Farmergreg]

My son uses vinegar.
For the longer pieces we made a shallow "pan" with 2X4's on edge on a plywood base and lined it with heavy plastic.

 

[bucky]

I have a plastic tray that’s the right size. I guess I’ll start with a small amount of acid and increase if needed. I have everything cut and ready to go.

 

[sab]

I may be posting too late for you - I just saw this thread. I use muriatic acid all the time to both strip zinc plating off steel (happens in a minute or two, with vigorous bubbling) and to take off mill scale (takes a lot longer than the zinc stripping - I leave it for 24 hours, and I've never had an issue). The stuff I use is the Klean-Strip muriatic acid from Home Depot, full strength, and I re-use it over and over again until it stops working (just pour it back in the jug when done).

Klean-Strip's MSDS is purposefully vague on the concentration of the HCl:

I have used many different containers over the years, but I recently made some die inserts for my press brake that were nested angle iron pieces 19" long (see this post for a picture). I put those in a capped 4" piece of Sch 40 PVC for 24 hours, and it worked great.

Also, I think @freedom_in_4low used vinegar in PVC pipe to clean scale off some tubing used to make the railings in his house a couple years back.

 

[freedom_in_4low]

I may be posting too late for you - I just saw this thread. I use muriatic acid all the time to both strip zinc plating off steel (happens in a minute or two, with vigorous bubbling) and to take off mill scale (takes a lot longer than the zinc stripping - I leave it for 24 hours, and I've never had an issue). The stuff I use is the Klean-Strip muriatic acid from Home Depot, full strength, and I re-use it over and over again until it stops working (just pour it back in the jug when done).

Klean-Strip's MSDS is purposefully vague on the concentration of the HCl:

View attachment 520981

I have used many different containers over the years, but I recently made some die inserts for my press brake that were nested angle iron pieces 19" long (see this post for a picture). I put those in a capped 4" piece of Sch 40 PVC for 24 hours, and it worked great.

Also, I think @freedom_in_4low used vinegar in PVC pipe to clean scale off some tubing used to make the railings in his house a couple years back.

Yes, I used vinegar. It took at least a day, 2 was better, and I found temperature played a role as well...it went faster when warmer.

 

[bucky]

I went with muriatic pool acid because it’s what I Had. I mixed 2 cups with 4 gal of water. It takes a few hrs to remove the scale. It does a great job. I rinse, blow dry and use a red scotchbrite to remove the flash rust. Pieces come out very clean and smooth. Almost dine with my project just 2 small pieces soaking now rest are welded up. I don’t know why I did not do this sooner the metal comes out great with no sanding marks.
Thanks for your input.

 

[Rickyd]

I've used muriatic for decades on period correct hardware on old cars. Metal prep and etch works too.

I recommend a 5 gallon bucket with a lid and do it outside. The fumes aren't good for you

 

[sab]

I recommend a 5 gallon bucket with a lid and do it outside. The fumes aren't good for you

Good point. In addition to doing my pickling outside, I don't even store the acid in the shop. The fumes aren't good for anything metallic nearby, either. I learned that the hard way...

 

[AirborneTexasRanger]

Are you trying to remove all the mill scale from the entire piece?

Edit: Nevermind, I just reread your post & saw it was for painting