Abe's post on cleaning parking lights prompted this... The concrete area in front of my shop is pretty badly stained from grinding and welding and not cleaning up properly. Lots of iron rust stain that has been there a long time. Is there anything that will work to remove, etch, etc these stains so when I pressure wash the drive I don't have this discolored area ??? Don't have pets to worry about but do have nice grass on either side of driveway so rinse off might be a problem for the grass.

thanks
John

 

John,
I have never tried this but what have you got to lose, ...........ok time but you must have tons of that, right?

1.  
   • Rinse and wash the concrete with soap and water before beginning. Dirt and dust will just get between your cleaner and the stain, making your work less effective...
   • Pour or spray lemon juice on the rusted surface.
   • Pour or spray white vinegar on the rusted surface in place of lemon juice for tougher stains.
   • Scrub the surface of the concrete with a brush...
   • Rinse off the concrete with cool water when you're finished

(Opinions/suggestions expressed in the post are not necessarily those of the postee.)

 

Hmmm Tom... never considered Vinegar... I'll give it a try... cheap solution if it works. I had same stains on vinyl siding and found a toilet
bowl cleaner that I brushed on and it cleaned the vinyl...don't know about concrete since the stain has probably leeched into the concrete..,

thanks
j

 

Will vinegar chemically eat away at the concrete?

You could just let it wear off naturally. See the rust stains beneath my truck? They are now gone.

 

Muriatic acid (HCL); you can get it in gallon jugs at Lowes. This stuff is concentrated and nasty; watch the fumes or wear a respirator. You need safety glasses, rubber gloves, and a stiff brush. Check the label for dilution for the type of stains you are removing. This is the most effective cleaner for concrete. Scrub but do not leave on long as it will etch the concrete if left standing too long; then rinse. Always pour acid into water, not the reverse. HCL is a much stronger acid than acetic acid (vinegar)

Concrete is porous so rust and oil stains embed into the concrete. I use it on my driveway because the POS UPS truck always leaks diesel oil when dropping off a package.

 

I used a product from Home Depot called Green Muriatic Acid. It is strong and has to be diluted and sometimes I even have to use a wire wheel of the air drill to break rust loose. By problem is mostly rust and battery acid leaking from my wife's electric golf cart. It takes several applications usually.

 

I have used muriatic acid for some situations, but as stated it can be nasty and it is not eco-friendly. I would try vinegar first to see what results you get. You can always ramp up if the situation calls for it.

 

 

A pressure wash will remove the majority of it...the sun and time will take care of the rest. I have used the acids and they do work, the only problem is that they make the treated areas very clean leaving white spots among the rest of the dingy concrete.

 

And watch where the rinse water goes. Your wife will be even more upset if you kill her plants and trees around the driveway.