[lewisk]

I have some nice looking dragon stones, I know someone use something like acid, toilet cleaner or CLR to clean stone to make it look better.

I went to homedepot today, I checked all cleaning liquid but all of them mentioned: DO NOT USE ON NATURAL STONE.

What is the best way to clean and remove calcium of stone?

Thanks!

 

[fplata]

The reason they tell you not to use it on natural stone is because it removes calcium and lime

 

[PlantedRich]

When you say clean, it may mean an umber of different things.

If you mean to remove calcium deposit that are often hard water minerals, a light acid will soften the deposits. If they are still too hard after washing, soaking a rag in vinegar and letting the rag lay on the rock for 15-20 minutes will sometimes get it soft enough to brush off with a stiff brush.

If you mean clean "looking" as in getting algae off the rock, I prefer bleach soaking. It will often work to kill the algae and then it can be brushed off. This works also if you just want the rock to be whiter.

 

[lochaber]

If you are looking to remove carbonates or hard water build-up (lime/scale/etc) using an acidic solution would probably be the easiest.

I'm not familiar with dragon stone, but with a quick image googling, seemed like a wide variety of rocks being called dragon stone. ADA lists theirs as being inert, but some of the pics I found looked like weathered limestone, so depending on where you got your stones and how much you trust the source, you may want to be careful using an acid.

I'd also recommend not using toilet or other household cleaners - a lot of them have dyes and perfumes added that could be hard to remove from the rock. Not sure about CLR, as I haven't checked the labeling.

Usually you can get a jug of acid (HCl?) reasonably cheap at a hardware store - I think they use them in pools a lot, or cleaning up masonry. Don't do this unless you are familiar with the safe handling and disposal of acids.

You may be able to just use a strong vinegar solution - I've read of people using this to treat concrete tanks and ponds before adding fish. requires a bit of monitoring the pH and changing the solution out as it rises, but is a lot safer.