Cleaning: Awakening & Resetting Unglazed Ceramics / Yixing

User avatar
Victoria
Admin
Posts: 2450
Joined: Sat Sep 30, 2017 3:33 pm
Location: Santa Monica, CA
Contact:

Sat Jan 30, 2021 3:44 pm

SmallSmallTea wrote:
Fri Jan 29, 2021 7:18 pm
Hello to all connoisseurs.

I inherited few Yixing teapots (fortunately) which is very mouldy and has ugly stains all over it (unfortunately).

Read a few threads which recommend Sodium Percarbonate as cleaning agent and tried Googling it up too.

Could not find any food grade ones (or are there any actually?), are industrial grade ones safe? Are there any trusted supplier or brand?

Thanks, hope I will be able to revive my “new” teapots and get them safe for brewing once more, making cups of good tea.

Cheers!
Welcome to TeaForum @SmallSmallTea. I recommend you proceed with instructions at beginning of this topic to remove mold and stains. “Sodium percarbonate is an eco-friendly chemical which decomposes into oxygen, water and natural soda ash when it contacts with water making it biodegradable and septic safe (though it is not grey water safe due to the high salt content).” https://www.biome.com.au/blog/oxygen-bleach-cleaning/
User avatar
Balthazar
Posts: 380
Joined: Mon Apr 02, 2018 7:04 am
Location: Oslo, Norway

Sat Jan 30, 2021 4:11 pm

One thing I have wondered... Is there any reasonwhy lye is not commonly a part of the discussion when it comes to resetting teapots? I recently treated a vintage cast iron pan to a lye bath and was mindblown when I saw how effective it was in removing almost a century's worth of gunk and grease. While it must always be handled with care (skin/eye exposure would be ... not good), it's food grade available and not really any reason for concern of residues after cleaning (as opposed to bleach).

But there must be a reason. Maybe clay reacts badly to it?
User avatar
pedant
Admin
Posts: 1155
Joined: Fri Sep 29, 2017 4:35 am
Location: Chicago
Contact:

Sat Feb 20, 2021 11:39 am

Balthazar wrote:
Sat Jan 30, 2021 4:11 pm
One thing I have wondered... Is there any reasonwhy lye is not commonly a part of the discussion when it comes to resetting teapots? I recently treated a vintage cast iron pan to a lye bath and was mindblown when I saw how effective it was in removing almost a century's worth of gunk and grease. While it must always be handled with care (skin/eye exposure would be ... not good), it's food grade available and not really any reason for concern of residues after cleaning (as opposed to bleach).

But there must be a reason. Maybe clay reacts badly to it?
i've never used it. but in theory, using NaOH might be ok, but it depends on the concentration (pH).

what would you try to accomplish? removal of patina via saponification (basically de-greasing the pot)?

concentrated NaOH solution can etch glass, so that's why it's always stored in plastic containers. it can also etch ceramics.

since NaHCO3 (baking soda) will also remove patina, i'd rather use that.
User avatar
Balthazar
Posts: 380
Joined: Mon Apr 02, 2018 7:04 am
Location: Oslo, Norway

Sun Feb 21, 2021 2:19 am

pedant wrote:
Sat Feb 20, 2021 11:39 am
what would you try to accomplish? removal of patina via saponification (basically de-greasing the pot)?
Yes, basically to deal with something like this.

But I was mostly wondering why it is never a part of the discussion, since it's food grade, so readily available and used for many other cleaning purposes. If it can etch ceramics, then that's certainly a good enough reason to not take any chances with it! :)

Edit: For those interested, here's the before (first three) / after (last two) images of the vintage CI pot I cleaned up with a lye bath, a bit of elbow grease and some vinegar (at the end, for rust removal)
User avatar
LeoFox
Posts: 336
Joined: Tue Sep 01, 2020 4:01 pm
Location: Washington DC
Contact:

Sat Feb 27, 2021 6:11 pm

Decided to clean my modern ruyi pot:
20201214_090954.jpg
20201214_090954.jpg (251.1 KiB) Viewed 79 times
20201214_091127.jpg
20201214_091127.jpg (318.24 KiB) Viewed 79 times
20201117_235057-2.jpg
20201117_235057-2.jpg (183.65 KiB) Viewed 79 times
After 2x 6 hour soaks with percarbonate and 1x soak with citric acid. Note the interior shot is at same orientation as the shot above.
20210227_185053.jpg
20210227_185053.jpg (232.94 KiB) Viewed 55 times
20210227_185158.jpg
20210227_185158.jpg (233.34 KiB) Viewed 79 times
Before, it looked like modern hong ni. Now it looks like some zini blend like jiang po ni?

Brewed up a sou with this pot. Not too different after the cleaning. The pot was not very muting before. After the cleaning, still not muting. Flavors seem a bit more focused - possibly because I got rid of all the old tea residue
Post Reply