I have a pile of old bricks left over from renovations. Since these bricks match the house's color, I want to clean and keep them. I started a bit with a chisel but gave up pretty quickly. I bought a slag hammer, but that didn't work particularly well either. I'm considering putting a wire wheel on the angle grinder. But that will probably create a lot of dust and damage the bricks. So, does anyone here have good tips on how to succeed with this?
sorry for the title....
sorry for the title....
If it's real clay bricks, maybe something strong and dissolving could work? I mean dissolving for lime, I've used a mixture called G60, unfortunately, I don't think it's sold anymore, but it was incredibly effective. Some mixture of hydrochloric acid, nitric acid, and a little something else. Strong but effective (used diluted, of course 
). Regular hydrochloric acid might work perhaps? You could try on a couple of stones at least, a larger tub, with a little mixture in it, rubber gloves (safety goggles are not a bad idea either!) and a brush could work. But the stones might need to soak for a while before you start.
Now, it's not really clear in the text, but I assume it's stones with plaster/mortar on them and nothing else?
). Regular hydrochloric acid might work perhaps? You could try on a couple of stones at least, a larger tub, with a little mixture in it, rubber gloves (safety goggles are not a bad idea either!) and a brush could work. But the stones might need to soak for a while before you start.Now, it's not really clear in the text, but I assume it's stones with plaster/mortar on them and nothing else?
Sounds interesting. I will have to try! I actually have some hydrochloric acid, I think. Do you have any idea what concentration is appropriate?
It is yellow brick and facade brick from the 60s that need to be cleaned from mortar. I don't think it's lime mortar. It's too hard!
It is yellow brick and facade brick from the 60s that need to be cleaned from mortar. I don't think it's lime mortar. It's too hard!
Can't say more than try a little and see how it works, then you can see if you should increase or decrease the concentration. If what you try solves it, just lower the concentration until it starts to feel like it's not working quite right. It's a bit unnecessary to use stronger than necessary.
I used the G60 I had to clean masonry tools, dissolve mortar on stones/floors, remove tile adhesive/grout, etc., it worked for everything cement-based. However, I don't know if pure hydrochloric acid is as effective; I'm a bit skeptical. But it can't hurt to try anyway.
Unless there's an extremely thick layer of mortar on the stones, I think some form of acid solution is the right way to go to keep the bricks as intact as possible.
Please report back with the results if you try. However, be prepared that it might take a while; even with my favored G60, I don't think it would be particularly quick to clean an entire stock of bricks (it's not really clear what quantities we're talking about here?
I used the G60 I had to clean masonry tools, dissolve mortar on stones/floors, remove tile adhesive/grout, etc., it worked for everything cement-based. However, I don't know if pure hydrochloric acid is as effective; I'm a bit skeptical. But it can't hurt to try anyway.
Unless there's an extremely thick layer of mortar on the stones, I think some form of acid solution is the right way to go to keep the bricks as intact as possible.
Please report back with the results if you try. However, be prepared that it might take a while; even with my favored G60, I don't think it would be particularly quick to clean an entire stock of bricks (it's not really clear what quantities we're talking about here?
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It's called "Kalkbort G60" and is (was?) used a lot in the plumbing industry to clean pumps and thermostatic mixers. In the past, as you said, it contained hydrochloric acid (and other things), but I believe the formula has changed or the product has disappeared entirely.
The product has completely disappeared, I can inform you. Ask my paint dealer where I bought mine, and it turns out they had to stop selling it, apparently "too dangerous/unhealthy." Good if it wasn't so beneficial perhaps, but a shame because it was extremely effective for everything related to use.
Hey again!
I just wanted to report back on the results of my attempts with hydrochloric acid. I diluted 1 part 30% hydrochloric acid with 9 parts water, i.e., 3% hydrochloric acid. It worked excellently but takes a bit of time. It works best if you remove as much mortar as possible with a wire wheel on the angle grinder first. I let the stones sit for about 10 hours, and then they were like new without any visible color changes.
I just wanted to report back on the results of my attempts with hydrochloric acid. I diluted 1 part 30% hydrochloric acid with 9 parts water, i.e., 3% hydrochloric acid. It worked excellently but takes a bit of time. It works best if you remove as much mortar as possible with a wire wheel on the angle grinder first. I let the stones sit for about 10 hours, and then they were like new without any visible color changes.