Today I just scored this 32 commercial grille for a deal I couldn’t pass up. Very solid, only a few small pin holes toward the bottom, missing the splash guard. Grille was hanging in a cement factory in PA for the past 40yrs. I don’t want to paint it, debating leaving it exactly as is or just trying to mildly knock off some of the surface rust to smooth it out. Read about using CLR, white vinegar and a light brush, paper towels soaked in lemon juice, light scotch bright sanding, etc etc. What are the best options? If I don’t have any without risking messing this piece up, I’ll leave it as is.
All of the things you suggest will tidy up some of the rust or kill it. Also search molasses on here. Clr is probably going to achieve best what you want, from what you say. Search some of those on here and compare before and after pics to see what is closest to your desired finished product. If you don’t want to stuff it up, - (your words) - sand it down or carefully sand blast it, treat the rust and paint it ! (and yes I did read that you don’t wish to paint it). .
Nice find. I had a '32 commercial grill on my '31 and found it to be a bit too "bulky" for the look I wanted. You, of course, might have a different situation, but you might want to test fit it and stand back before you get too involved. If you do use it, keep us posted on what works, or doesn't. Best.
Ok, these pics are of a rusty ''cast iron'' (not panel steel) Japanese lantern thingy, before and after soaking in white vinegar for a few days, then a quick scrub with a brush.. I have used it on rusty totally seized steel tools that I've found, and they came out just as good..
https://www.jalopyjournal.com/forum/threads/whats-the-story-on-using-clr.990241/ https://www.jalopyjournal.com/forum/threads/clr-method-procedure.616168/ I would think that all of the above ways would continue to rust, unless you somehow seal them after treatment.
I just completed a rust removal project. White vinegar worked well on surface rust and on pitted areas. A couple of nylon scrub brushes cleaned up the items with no damage. I think vinegar is the least likely to cause you to 'overdo' the process. I rinsed off my project and put it back in the same vinegar one time and it worked just fine for the second dip.
Be sure to plan for the radiator neck to be further forward than the Model A. You might consider a dummy cap and the radiator filler under the hood. Charlie Stephens