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Didn't someone (I think it was Kyarazen) make tests with just using hot water in Yixing? > It became shinier over time, without any tea used inside. So there must be more at work than oils.

I don't wet-brew or otherwise use tea to brush the outside of my pots. Yet, without exception they become shinier over time. The lid know and handle of course more so, as they are touched constantly.

Bok wrote: ↑

Mon Mar 13, 2023 2:17 am

Didn't someone (I think it was Kyarazen) make tests with just using hot water in Yixing? > It became shinier over time, without any tea used inside. So there must be more at work than oils.

Maybe this: https://www.kyarazen.com/patina-develop ... xing-pots/

Andrew

Andrew S wrote: ↑

Mon Mar 13, 2023 2:21 am

Maybe this: https://www.kyarazen.com/patina-develop ... xing-pots/

What this doesn't explain is why they become mat again if I reset them with Sodium Percarbonate... so I think his conclusions are probably not right.

Bok wrote: ↑

Mon Mar 13, 2023 3:10 am

Andrew S wrote: ↑

Mon Mar 13, 2023 2:21 am

Maybe this: https://www.kyarazen.com/patina-develop ... xing-pots/

What this doesn't explain is why they become mat again if I reset them with Sodium Percarbonate... so I think his conclusions are probably not right.

Perhaps the clay absorbs the water and thus changes the teapot's colour (many things differ greatly when wet and when dry), which can appear more pronounced at the handle or the lid knob which are touched more often and have contact with the moist skin of the hand (as you've mentioned). Sodium Percarbonate is hygroscopic, so it could eliminate moisture accumulated in the teapot's clay and remove the patina. That's my proposition.

@Bourder not sure about that. The patina stays, even when pots are left alone and presumably completely dried out for weeks/months.

I think there are 2 different things in play as mentioned:

1) oils and waxes from ones hands, tea, etc., giving the surface a shine - these wash out with sodium percarbonate

2) physical change to the surface of the pot, gradual smoothening through repeated expansion/contraction and surface rubbing - these are permanent changes. For example, some green label F1 pots can have a sort of slightly chalky feeling when unused and gradually smoothen over the time.

The more smooth the surface, the quicker the oils give it shine (other things play role too: the clay, its processing, surface burnishing and firing are still the most important factors). This is all in line with what KZ says:

With regular usage, even with just hot water alone and no tea used, a pot can start developing a nice patina. This is due to the repeated expansion and contraction of the pot surface, micro particles can fall off, making it smoother with some shine.
It gets even better when you use tea! Tea interacts with the clay, with some of the tea compounds possibly binding to the clay surface. Some of the minerals present in the water can also bind to the clay in micro quantities. After some usage, take a cotton cloth and give the pot a nice rub, you may see the patina becoming even more glossy.

.m. wrote: ↑

Fri Mar 10, 2023 8:36 am

WhisperingFrog192 Nice!

I've just read this theory that some of the more crude Cultural Revolution products were made outside of F1. Personally, this doesn't make sense, i think more likely there was quite a bit of of variation in terms of quality: maybe less skilled workers, tiredness at the end of shift and rush to meet a quota...

http://www.zhongguociwang.com/show.aspx?id=15039&cid=87

Although the purple sand craft factory fell into a sluggish production state due to social and political reasons in the early stage of the Cultural Revolution, and the product quality dropped greatly, but the state-owned factory has its basic quality inspection requirements and process specifications after all, so some of the crudely made purple sand during the Cultural Revolution period we came into contact with The teapot is not a commercial pot produced in the factory, but a so-called "country billet", that is, a purple sand teapot made by non-factory workers. Just as some older workers of the Zisha factory said: Even during the Cultural Revolution, the No. 1 factory did not completely relax its product quality.

The F1 plum trunk pot arrived safe! It's interesting to compare and contrast with the other plum trunk pot I have.

@WhisperingFrog192 Awesome!

There are studies that show that patina is at least partially from tea compounds. Here's one: https://www.sciencedirect.com/science/a ... 9814000945

nohwonder wrote: ↑

Tue Mar 14, 2023 4:29 pm

There are studies that show that patina is at least partially from tea compounds. Here's one: https://www.sciencedirect.com/science/a ... 9814000945

I don’t think anyone doubts that.

Weren’t we discussing that specific teapot, not patina in general?

Baisao wrote: ↑

Tue Mar 14, 2023 11:40 pm

I don’t think anyone doubts that.

Weren’t we discussing that specific teapot, not patina in general?

Apologies, guess I misunderstood. I thought people were claiming that patina didn't really come from tea. Either way I think this is an interesting study.

I need to talk to some lab people who do nothing else but chase organic compounds to see if I can get pots analysed.

Meanwhile, I received a broken sister pot to my oolong pot and thought I'd share for two observations.

1. The construction with a hollow handle, conveniently busted for viewing pleasure, which I am told is to prevent kiln explosions with this particular clay. Looks like it may also introduce a weak spot for impacts during shipping. There is also a little outlet hole under the handle (which some of you may remember from a previous post where I wondered what it was for) so that air space is not sealed within the handle.

2. Another example of patina development, the source of which remains a mystery for now, after about 7 weeks of daily use versus unused.
It's quite obvious in person that one shines and the other is dull, the reflections here capture it reasonably well. There is also a slight colour variation, which I can't attribute to either firing or repeated heat cycling since I did not receive them at the same time.

@Baiyun Interesting that they do hollow handles, it has never been necessary in old times to do that.

I'd be inclined to think it has to do with mass production automation, rather than the clay itself... or to save material and/or make it lighter.

Bok wrote: ↑

Wed Mar 15, 2023 7:15 pm

Baiyun Interesting that they do hollow handles, it has never been necessary in old times to do that.

I'd be inclined to think it has to do with mass production automation, rather than the clay itself... or to save material and/or make it lighter.

I don't think they would mass production automate the handle on this specific pot given that there are visible differences in the body, spout and lid knob that align with it it being marketed as fully handmade. It's not a heavy pot either, I doubt it would matter for the handle to be solid. The statement re preventing kiln cracks or explosions is from the vendor. In context, I would think it is possible that they implemented a workaround to prevent some common failures, but who knows?

Picked up these two a little bit ago! Anybody got any information on what "C.C.T." is or what the numbers/writing on the bottom means?