Cleaning: Awakening & Resetting Unglazed Ceramics / Yixing

[Bok]

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.

Foam is normal! The dirtier the more foam! Sometimes it fills my whole sink.

[Mark-S]

@Bok Nice, thanks, @Bok

[Youzi]

@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.

[Victoria]

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.

[teanik]

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.

[Bok]

@teanik try citric acid. Waxy sounds weird though… often white spots are lime scale, but these wouldn’t be wax like…

[teanik]

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.

[LeoFox]

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

[teanik]

Thank you, @LeoFox.

[karma]

I’ve tried every method suggested in this thread to clean a musty-moldy-gross aroma out of a pot, including sodium percarbonate and clorox. I’m contemplating just putting this pot in the oven on self clean. The pot originally had what seems to be urushi lacquer spilled on the inside.

Anyone got any ideas?

[Victoria]

I’ve tried every method suggested in this thread to clean a musty-moldy-gross aroma out of a pot, including sodium percarbonate and clorox. I’m contemplating just putting this pot in the oven on self clean. The pot originally had what seems to be urushi lacquer spilled on the inside.

Anyone got any ideas?

Can you provide pictures of this pot?

[karma]

I’ve tried every method suggested in this thread to clean a musty-moldy-gross aroma out of a pot, including sodium percarbonate and clorox. I’m contemplating just putting this pot in the oven on self clean. The pot originally had what seems to be urushi lacquer spilled on the inside.

Anyone got any ideas?

Can you provide pictures of this pot?

Here are some both when I got it, after I cleaned the first time, and after I removed the spout. Can be more thorough if I know what’s needed.

[DailyTX]

I’ve tried every method suggested in this thread to clean a musty-moldy-gross aroma out of a pot, including sodium percarbonate and clorox. I’m contemplating just putting this pot in the oven on self clean. The pot originally had what seems to be urushi lacquer spilled on the inside.

Anyone got any ideas?

@karma
This will probably take some time. Let the pot bath in clean water. Do a water change daily, and evaluate each time you do water change. My last Yixing pot had this issue. It took an extra 2 day of bathing to get the moldy smell out after a full reset. Good luck!

[teatray]

I love the look of that pot. It's like it lost a limb but got a steampunk mecha replacement (with the steam to prove it, when it's in use). Hope it soon makes tasty tea!

[.m.]

@karma I've a somewhat similar issue with a low fired yixing kettle (viewtopic.php?p=37207#p37207)
It wasn't musty, but had a strong "wet terracotta smell". I cleaned it multiple times, sodium percarbonate, vinegar, baking soda, many rounds of boiling water, but it was still there, also the water had somewhat chalky texture. At some moment i've just started using it. 100 boils later, the smell is all gone, it makes a really nice soft water. I second @DailyTX, it may take some time and patience...