Some years back, I made this dragon head fountain. It's made of mostly unglazed black stoneware clay (the eyes and teeth have transparent glaze).



I keep it outside all summer and then take it in to save it from the frost. By the time I take it in, it's always grown a green beard.



I clean off the green, no problem. The lime deposits, however, is a different matter. It builds up more every year and I haven't been able to get it off.



So I was wondering if anyone here might have a good idea for how to clean lime off of unglazed clay without damaging it? Would it be okay to try vinegar?

Ylis

The only thing I can think of is bleach which may damage the stone/clay so hopefully someone will stop in and know the answer.

I really couldn't find anything for unglazed pottery.

Anything acidic dissolves lime, so vinegar or low concentration hydrochloric acid

Cool Dragon head!

that is a great piece!
also, I'd try vinegar.

Thank you for confirming the safe use of vinegar.

This is the before and after. It's not perfect, but it's better.

Now he can chill with his buddies without shame.

Sometimes the vinegar has to soak a bit, there is also Lime Away, but I prefer vinegar - the 5% or the 10% I have to use on garden nozzles, bathtub heads at least every 6 months, even for the green on the step stones here. Then rinse with clear water, and the vinegar will dissipate as it dries.

Ylis, those are amazing

kittriana said: Sometimes the vinegar has to soak a bit, there is also Lime Away, but I prefer vinegar - the 5% or the 10% I have to use on garden nozzles, bathtub heads at least every 6 months, even for the green on the step stones here. Then rinse with clear water, and the vinegar will dissipate as it dries.

I used 12% (we have 12 and 24% here) and diluted it. Most of what came off was gone after an hour of soaking, but the rest was more stubborn. A little bit more came off after two more hours, but even when I left it over night, I couldn't get any more off.

I'll just jot the remains down as "patina". ^^;

sallyg said: Ylis, those are amazing

I just like to release whatever creature happens to be hiding in the clay and let it live in my garden/house. And that black clay is a dream to sculpt.

sallyg said: Ylis, those are amazing

what a great talent you have Ylis!

@dirtdorphins Thank you for the acorns!

And thank you @GigiAdeniumPlumeria !

Love these dragons!