First rule and one to never break. Always Add Acid. Don't put water in straight acid. Protect your eyes. Wear a respirator unless there is abundant flowing fresh air. Keep a garden hose at the ready to wash acid or acid mix of you or anything else it gets on that it shouldn't.
Add the acid to the clean water. You want to add a little acid to your mop/slop bucket 1/2 full of water and then test it on the cement. If it does nothing add some more acid to the water and test again. Keep adding small amounts and testing until you get light white foam with very little to no white smoke. Wash the floor with this strength solution. The acid will etch the floor and as it does it will chemically change from an acid to a salt. When it does this it will stop working and you will see no action. Keep adding more solution to the floor to keep the visible action going. don't push dead etch water around. A right strength mix will it do nothing after a couple of min at best. Keep adding more fresh solution as you go. I like to use a mop they work better than most brooms at low concentrations. I use a stiff broom during the final rinse clean phase.
Too weak. No foaming action. No eching.
Just right. Light white foaming, the bubbles break and there are no blobs of thick foam remaining. Almost no stink. Wear a mask regardless unless there is lots of air flow.
Slightly too strong or for hard to etch spots. White foam with slight white smoke as the foam forms and bubbles.
Real strong. Thick white to yellow foam and white smoke.
Too strong for cleaning floors. Thick yellow foam abundant smoke and strong stink.
Straight up. Thick yellow foam yellow to white smoke, foam lingers. This will eat into the surface enough to weaken the surface layers and reduce coating adhesion.
How to keep the eching solution from eating stuff you don't want it to.
1. Wet other surfaces down before hand. Dry surfaces etch or get damaged more easily than wet.
2. Use only the lowest strength you need and no more. Take yer' time and give the acid time do the work. Weaker and longer is better than stronger and shorter.
3. Let the solution go fully inactive before rinsing. The acid will combine and as it turns into salts it will stop fizzing and etching. You can walk barefoot in combined out acid that would have stung your feet 10 min earlier.
4. Baking soda. If you have a surface you don't want touched but need to run spent etch water over after the etching is done you can shut the etch water down fully with baking soda. Do the floor with the weakest solution that gets results. Let the acid combine out and then for added safety sprinkle baking soda all over the floor and push it around with a push broom. Slop it in the puddles and then push the puddles around all over the entire surface. Get baking soda water on all treated surfaces. Now you can rinse the solution away without etching anything else. For plants that are down stream flood with lots of water. LOTS OF WATER. Let the water run to dilute the salts.
Muratic acid will not eat you like in the movies unless you are made from rotten cement.
These are great instructions...
In addition... I've found 2 different common muriatic acid strengths. The most widely available is for swimming pools. I've found stuff in the paint section of a hardware store (Orchard Supply Hardware) that is twice as strong. So... Vicegrip's advice about dilution works regardless of what strength you purchase.
In my case, with desert conditions (9% humidity), I had to work to keep slab wet with water/acid solution -- the slab would just dry after a couple minutes (even though I flooded the slab ahead of time to get it wet), and the directions I received said don't let the slab get dry.
Judging by Vicegrip's description, I probably used too strong a solution -- the fumes caused some paint on the drywall to "melt away", as I recall (although maybe it was small splashes of acid -- I was using an old fashioned plastic flower watering can to sprinkle the mixture on the slab).
In my case, just flooding / powerwashing with water was sufficient without neutralizing with baking soda. The "spent" solution from the slab went down the concrete driveway to the concrete gutter to a storm drain without leaving a mark .
I had some "spent" solution end up on some plants on either side of the driveway. I gave surrounding plants lots of water just in case - nothing died.
Oh - I used rubber boots during the process "just in case."
Afterwards, powerwash, powerwash, powerwash and powerwash some more .. anyway that's what I did.
Take some before & after pictures & let us know how it turns out!
