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muratic acid qty.

dankeenan

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May 21, 2008
Messages
180
I am getting ready to to acid etch my floor in preperation of epoxy coating. The garage is 24 x 28 with new concrete. I am wondering how much acid to get to etch the floor. How much has everyone used versus the size of their garage.

Dan
 
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azone

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Joined
Nov 13, 2009
Messages
43
my garage is the same size. I used (4) gallons of 30% muriatic acid. I diluted it with water 3:1. I probably overdid it though, I tend to do that. You can probably dilute it more. You can get the 30% stuff at pool supply stores, it's about $4/g. You can also get it in the outside garden area at Home Depot or Lowes in 2g packs for about the same price but it's only 15% HCL.
 

hartattack

Member
Joined
Jul 19, 2009
Messages
22
My garage is 20x28 with new concrete and i used 6 gals. I tried using 3 to1 ratio and found it did not do much of anything. I ended up using a 1 to 1 ratio.
 

Cobra5L

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Mar 3, 2009
Messages
38
Location
BC, Canada
I only used 2 gallons of acid and mixed it 4:1 with water. Not sure on the % the acid was to begin with. The key thing I noticed, was pour a little down at a time, then use a broom to agitate it. If you pour it all on at once, the acid will stop working before you get to the spots you missed (this was the 1st gallon, hence why i did it again). BTW my shop is 25x30 (750sqft) with new concrete.
 
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dankeenan

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May 21, 2008
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180
Thanks for all the help. I will check out the local pool store tomorrow.

Dan
 
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Bullet120

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Nov 3, 2009
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40
I used the premade stuff at lowe's, no good.

Used 30% at 3:1, not good enough.

Used 2 gallons at 1:1 for a 22 x 22 and let it set for 30 minutes. Much better but could stand even more.

Not sure if the scrubbing or set time helps, I think most of the work is done as soon as it stops fizzing, which was about a minute for me.

Definitely must powerwash like crazy to clean out the pores and that's when I finally could feel the roughness you're looking for.
 

rlme36

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Feb 17, 2008
Messages
331
on my 30x36 I used 6 gallons as I etched it twice with the Muratic as the 2 times with the phosphoric did nothing but make it clean. Mine is new concrete, so results may differ. I would definitely pressure wash and scrub 2-3 times. You only get one chance at getting this right.

rob
 

Domino

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Joined
Nov 20, 2009
Messages
3
The directions on the label for the acid I got says to dilute 25:1. From what everyone is saying, I guess that is way too diluted? I think it's 31% HCL.
 

AlphaGarage

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Apr 16, 2008
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1,298
Location
Every Garage, AnyTown, USA
Different strengths of the bottled acid, different concrete compositions and conditions, these factors make it impossible to predict how much acid will be needed to properly profile a floor. So to figure out what works for your floor run a quick test or two.

First read all package instructions and warnings, muriatic acid is one of the most hazardous products sold retail, it is caustic and toxic, so wear protective gloves, face coverings etc.

Your floor should be thoroughly cleaned and degreased beforehand with no sealers or previous coatings.

Pre-wet the floor so that it's damp, not standing water, just evenly moist without puddling.

Now to test for the correct strength - Start out with a mix of about 1 part acid to 3 parts water (always pour the acid into the water - slowly!), just a small amount, say 1/2 cup acid to 1.5 cups water. Pour this on an inconspicuous spot, what you want is a strong enough mix that causes a reaction, fizzing and bubbling, that's the acid reaction with the calcium in the concrete. If the mix just sits there like water, it's too weak; if it smokes and foams, it's too strong. Once you've found the correct mix of acid to water you're set to do the whole floor.

Again make sure the entire floor is damp - not too wet with standing or puddling, just damp.

Have a stiff broom ready (check first to make sure the bristles don't react with the acid), protect any areas you don't want acid to hit, remember that muriatic acid is caustic to metal - even its fumes can damage metal!

Figure you'll have about 15 minutes to work with the acid on the floor, you do not want the acid mix to dry on the floor, so don't etch too much area.

Evenly apply oyur acid/water mix, I like using a all plastic flower watering can. Broom the mix to work the acid into the concrete and promote reaction. The acid will do most of it's work in 10 - 15 minutes, so after about 15 minutes completely rinse the area with water and/or neutralize it with a mix of 1 pound baking soda with 5 gallons of water. If you don't use baking soda, be careful with the run off rinse water and don't let it run onto any landscaping, it may still be a bit "hot".

Repeat the process until the entire floor has been etched. Using a baking soda solution to neutralize the concrete is strongly recommended. A like with the acid solution, do not allow the baking soda mix to dry on the concrete.

When completed your floor should have the texture of 80 - 120 grit sand paper. Some floors will need more than one application of acid to do the trick.

If you want to chemically profile the floor, but can't or don't want to deal with a chemical as harsh as muriatic acid, there are other chemical available. We offer OrganiPrep, far less toxic and smelly, but as effective, but it does cost more.
 

bob1234

Member
Joined
Nov 9, 2009
Messages
21
Should I have to worry about the broom dissolving in the acid? If so, what else can I use to move the acid/water mixture around?
 
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