Cleaning: Awakening & Resetting Unglazed Ceramics / Yixing

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Bok
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Wed Jul 14, 2021 7:08 pm

Mark-S wrote:
Wed Jul 14, 2021 4:54 pm
I've started to clean my 🐿️ pot with Sodium Percarbonate today and there was much foam in the pot. Is this normal? :| Before the Sodium Percarbonate bath I put it in water with some Sodium Bicarbonate for about one to two weeks... but I rinsed it afterwards.
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Foam is normal! The dirtier the more foam! Sometimes it fills my whole sink.
Mark-S
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Wed Jul 14, 2021 11:31 pm

@Bok Nice, thanks, @Bok ;)
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Youzi
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Wed Aug 04, 2021 5:53 pm

@Victoria

Any idea or opinion on using EDTA to clean teapots?

In this paper where they studied tea stain formation they used that to clean the stains, among others, and it worked the best.
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Black tea stain formed on the surface of teacups and pots Part 2.pdf
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Victoria
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Wed Aug 04, 2021 8:01 pm

Youzi wrote:
Wed Aug 04, 2021 5:53 pm
Victoria
Any idea or opinion on using EDTA to clean teapots?

In this paper where they studied tea stain formation they used that to clean the stains, among others, and it worked the best.
Very interesting study. I haven’t heard of this before, so thank you for sharing @Youzi. Just yesterday, I used a baking soda rub, followed by a white vinegar wash to remove oxidized tea stain residue on a few porcelain cups. I’ll definitely look into this though.

Wiki
Ethylenediaminetetraacetic acid (EDTA) is an aminopolycarboxylic acid with the formula [CH2N(CH2CO2H)2]2. This white, water-soluble solid is widely used to bind to iron and calcium ions. It binds these ions as a hexadentate ("six-toothed") chelating agent. EDTA is produced as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA.
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teanik
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Fri Nov 19, 2021 6:08 am

I'd be grateful for some Yixing cleaning advice.
A friend of mine bought a hong ni pot some time in the 90's. He collects ceramics and bought it for display only, so it's never been used. I figured it was time we cleaned it up. If he doesn't use it, at least I'll be able to use it when I visit,
We soaked it by submerging it in a pot of room temp water for a day and a half, changing the water regularly. Then it simmered in a pot for an hour or so. When we took it out, the interior and exterior walls of the pot looked and felt clean. The underside of the lid felt clean. But the top of the lid had what looked like white-ish stains. When I touched the stains they were waxy. As it was time for me to leave, I simply wiped off what I could of the waxy substance, but it didn't all come off.
My friend likes black tea, so we made some Jin Jun Mei, which turned out well and he enjoyed it.
We don't want any waxy stuff leeching from the lid into the tea, so some further treatment is needed.
I've read info on this site about cleaning dry stains on old pots, but not waxy ooze. Does anyone here feel that repeated simmering in hot water will eventually de-ooze the lid, or is there some other material it can soak in for a while?
Thanks folks.
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Bok
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Fri Nov 19, 2021 8:36 am

@teanik try citric acid. Waxy sounds weird though… often white spots are lime scale, but these wouldn’t be wax like…
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teanik
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Fri Nov 19, 2021 10:05 am

Bok wrote:
Fri Nov 19, 2021 8:36 am
Waxy sounds weird though…
30 years sitting on a shelf absorbing everything from car exhaust to cooking oils, I guess. Something may have even spilled on it during a move.
Citric acid it is. Thanks, @Bok.
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LeoFox
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Fri Nov 19, 2021 12:12 pm

teanik wrote:
Fri Nov 19, 2021 10:05 am
Bok wrote:
Fri Nov 19, 2021 8:36 am
Waxy sounds weird though…
30 years sitting on a shelf absorbing everything from car exhaust to cooking oils, I guess. Something may have even spilled on it during a move.
Citric acid it is. Thanks, Bok.
Should just go ahead and do percarbonate over night soak while you are at it
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teanik
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Fri Nov 19, 2021 7:11 pm

Thank you, @LeoFox.
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