Removing concrete stains

I have a bunch of tool boxes used by masons, which have some concrete stuck on them.
I want to remove that stuff quickly and efficiently and it is a lot of
items (four huge Knaack field stations, Knaack gangboxes and many concrete saws).
What is the best and easiest way/chemical etc thanks
I tried a power washer, it seems to work on some stains and, miraculously, not on others.
i
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Sand blasting ?
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Ignoramus11693 wrote:

Vinegar or just about any weak acid . How about that stuff they sell at the BigBox stores for cleaning mortar residue off new brickwork ?
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Concrete is mostly sulfates, which don't dissolve easily in things that won't adversely affect the boxes.
If the "stains" are mortar, they'll come loose with a mild acid. If they're really Portland-based concrete, mechanical abrasion with water is the quickest way.
Lloyd
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For the gangboxes, I would try whacking them with a piece of wood, or using a piece of wood like a chisel.
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On Thu, 15 Mar 2012 17:22:24 -0500, Ignoramus11693

When my chimney was built the stone mason used muriatic acid to wash the mortar stains off of the stones. I think he diluted it but I don't know how much. Anyway, the stones were all stained with mortar and after he washed them with acid they were all very clean. Muriatic acid will not damage the steel but will remove rust. Of course using any acid will require good rinsing afterwards to avoid rusting. Eric
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On Thu, 15 Mar 2012 20:40:47 -0700, snipped-for-privacy@whidbey.com wrote:

Common muriatic acid sold in gallons is 32%, or 20 degrees baume. It should be diluted 1:10 with water (3.2% solution). And use an alkaline neutralizer (baking soda and water, etc.) to keep it from continuing to etch the crete after you're done. Acid residue keeps finishes from sticking, too.
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