Acid washing question

18 years ago

This may not be the right place to post this so I will post it in the porches board also, but I need some advise about acid cleaning the stone columns I just built. There doesn't seem to be a concrete discussion board anywhere!! lol!

I have a bottle of acid. The back of the bottle says dilute it 1:20. I saw some directions on the web that says 1:4 dilution! 1:20 does practically nothing. It removes the haze, but the not the excess spilled mortar and mortar fingerprints. I have not grouted the joints yet either, but there is a lot of mortar between many of the joints anyway just from the process of sticking the rocks to the columns. If I mix the acid 1:4, can it damage mortar and make the rocks come loose? I mean can it soak in and weaken it....or will it only eat away at the exposed mortar? I don't want to damage anything....but I would love to get the excess mortar off without having to resort to a grinding wheel. There isn't that much....but the rocks are black and every little speck of mortar really shows. thanks for the help.

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Comments (5)

fishpants
18 years ago
Do you have true rock or the veneer type? The reason I ask is because the acid wash will destroy the coloring on the veneer. We have a good friend who is a mason and had a client insist of doing the acid wash. He cringes every time he drives by and sees the place. He says it reminds him of when a rainstorm hits and you can see the light/dark areas where the raindrops have hit/missed. Unfortunately, the look is permanent. If you have black...
ccoombs1
Original Author
18 years ago
They are real rock. I don't know what kind they are.....but they are VERY hard. I did acid wash some yesterday with about a 20:1 dilution and that got the mortar haze off them really well. The rocks are beautiful! Unfortunatly, cleaning them up made the thicker areas of mis-places mortar really stand out. It is the thicker stuff I need to remove still.
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brickman
18 years ago
O boy .....the heavier stuf you are going to have to remove manualy either with a trowel or chissel / scraper, or if it is still soft enough, with a wire brush, this will be time consuming, and try not to leave scrape marks in the stone when you are doing it , then clean with the acid making sure to wet the stone first and rinse thoroughly afterwards.. heavy rubber gloves & eye protection are a must..
When all is completely dry use a grout bag to grout in the joints, experiment with the grout mix usually slightly richer & softer mix (cake icing or dq ice cream consistency) will be best but dont make it sloppy or you will have the same problem. when the mortar is firm to the touch then tool it as you want. Again make certain this is real stone before proceding
have fun
Martin
lsst
18 years ago
Can you take a pressure washer to the mortar to "etch it out"?
I did this to our stone to get the remaining mortar off. I think we have the same stone and it did not affect ours in a negative way.
ccoombs1
Original Author
18 years ago
Thanks brickman....that is what I was afraid of. OK lesson learned.....be neater with the mortar!! I did put a small wire wheel on a drill last night and had pretty good sucess with it....but it is going to be time consuming.I am getting a larger wire wheel today and put it on the grinder (more RPMs) and see if I can make faster progress. This stone is bullet proof!! All that wire brushing didn't scratch the stone at all. Lsst....I'll try that too. My MIL has a nice pressure washer...I think I need to go borrow it for a day and see if that works.