Question about priming mild steel after acid washing

[V-10 Killer]

I've got a box grader I just welded together that I need to get primed. I'm going to wash it down with either muratic or works toilet bowl cleaner and water, but there's still going to be mill scale. I don't have a sandblaster and don't feel this worth paying someone else to blast it.
So my big question is, what primer will work best for this application. I have a quart of Rustoleum Latex primer for aluminum and galvanized metal, but I don't know if that'd be useful here (especially being latex based).
I expect this will flash rust fast after etching, so would something like Rustoleum Rusty Metal primer, or Clean Metal primer (mentions can be used over light rusting).

I plan to top coat it with Rustoleum Gloss Black, mainly because I have it laying around already.

What's everyones recommendation on this?

 

[trbomax]

Definitly dont use anything thats latex.Ive used the rusty metal formula a lot and the mill scale wont be an issue.Very few comercially built trailers or impliments are de-scaled before painting, and most dont even use a prime coat.Use the oil base rusty metal with a gun,not a bug bomb,and top coat it with regular rustoleum. I would thin the topcoat no more than 10% with xylol and give it a tack coat followed by a full coat. keep in mind that you are shooting air dry enamel and dont try for a really full,wet top coat,it must flow and runs easily. Good luck with your project!

 

[trbomax]

One more thing,when you rinse the acid, blow the part dry paying special attention to any cracks,gaps and welds. Blow them completely dry. Rinseing with hot water is way better than cold,I prefer a hot water power wash for this,but I know most people dont have that option.Dont worry about the flash rust,it will be fine.

 

[LG63]

Is it new or used steel? If used, I would skip the acid and just hit it by hand with a wire brush and then go with a zinc chromate primer. If new steel then acid will help remove the mill oil but muratic is nasty stuff. You might experiment with some purple degreaser (sold under several brand names) as an alternative.

 

[koditten]

Man are you over thinking this. Acid wash, rinse, let flash over. Paint it with rustoleum or something similar. If you really want to do it right, use the truck bed liner paint. Wally world-40 bucks.

Like said by Turbo, blow dry the crevices.

Later

KO

 

[HMCFab9]

Muriatic acid is really nasty stuff, but it should dissolve the mill scale. Apply it & you can work it in a little with a scuff pad. Do a section at a time & dry. If you acid wash the whole thing at once & rinse it, you will have a ton of flash rust. Make sure you neutralize the acid after washing. Prime with the rustoleum & paint.
You could also go to an automotive paint supply store & ask about acid etching for cars. That may work better than the muriatic acid.

 

[PKAero]

I agree w/ LG63. Zinc chromate on bare steel (and other bare metal) is the way to go. Being involved w/aviation over the years I have used gallons of the stuff. I have found that the Rustoleum brand (self etching primer) works fairly well and the Dupicolor is a bit better. Would not go with mill spec aviation grade due to price. I clean my garden tractor implements and spray w/ this stuff, no top coat just primer, the stuff last for years, no rust.

 

[V-10 Killer]

Man are you over thinking this. Acid wash, rinse, let flash over. Paint it with rustoleum or something similar. If you really want to do it right, use the truck bed liner paint. Wally world-40 bucks.

Like said by Turbo, blow dry the crevices.

Later

KO

Me overthinking things, so what's new there. I thought about having you come back for coffee, but somehow you got the night off work....
BTW, congrats on finally ordering that lift

 

[V-10 Killer]

Oh believe me guys, I know acid hazards, but I appreciate the concern. Compared to what I work with every day, I could practically drink muratic lol (hopefully obvious sarcasm). But I have a gallon of it left over from etching concrete for my epoxy floor and thought it would be a good way to use it up so I can free up that shelf space.

I always try to see if I can use what I have first, so I can prolong getting to that eventual stage of having 50+ half full containers of paint/primer/stain/etc. taking up space in the garage.

 

[retrobuilder]

Muratic acid is better for concrete. Use one of many people friendly rust oxide removers or converters.

If a serious repaint- check out some great info at Southern Precision Urethanes website forum.

Wire the excess on top, chemical clean deeper to grain of metal - rinse to remove residues then prime, fill..etc.. Avoid cheap sandable ( fast dry) primers.

Not that hard to do quick and easy..

 

[retrobuilder]

SEM makes an aerosol excellent primer but $ for can spray. Duplicolor is okay too- high build primer fills shallow pitting. If outer body work- use a temperature proper 2 part epoxy spray gun applied coating.

 

[cbogg]

+1 for the sem. Shop I worked at used it on hitch plates, never descaled. Just a wipe down with some thinner to get the oil off and shoot it black. Works awesome.