Cracks in my new Yixing cup

[Oolonga]

I recently bought four Yixing glazed cups and have been using only one of them for almost a week now. I use it mostly for oolongs and chinese greens and haven't washed it with any detergent yet, just rinse it under running water with a sponge.

The problem is that after a few days of using the first crack appeared on the enamel inside the cup. It starts at the rim and goes down not reaching the bottom. I never dropped this cup and they all came very nicely packed.

Then a few day later I noteced the second crack and today - the third...
I'm very upset, it's my first Yixing cup and I don't know whether I'm doing something wrong or it's just a bad quality cup...

[bearsbearsbears]

it's common with glazed yixing cups/gaiwans/pitchers to develop cracks. the glaze isn't formulated well, so it doesn't fit the piece. either that or the clay expands more than the glaze does when the tea heats both, causing the crack. i avoid glazed yixing because so few pieces are made well, even though they're pretty.

[gingkoseto]

it's common with glazed yixing cups/gaiwans/pitchers to develop cracks. the glaze isn't formulated well, so it doesn't fit the piece. either that or the clay expands more than the glaze does when the tea heats both, causing the crack. i avoid glazed yixing because so few pieces are made well, even though they're pretty.

Yeah I believe that's the reason. It hasn't happen to my glazed yixing cups (yet ) but I heard it happens a lot. If it's new, you deserve a refund from the seller because this shouldn't happen to qualified ones.

However if one is lucky, the inside of the cup may end up with pattern similar to this

[Chip]

But isn't this occurrence different from what has happened here? Crackle glazing is an intentional condition.

[ABx]

But isn't this occurrence different from what has happened here? Crackle glazing is an intentional condition.

I think it was a joke, Chip

[Chip]

OH? Ohhhhh .....

[bearsbearsbears]

But isn't this occurrence different from what has happened here? Crackle glazing is an intentional condition.

Crackling only after applying heat (such as hot tea in the cup) is a classic example of a poorly formulated glaze showing its defects later, so in a sense you're right.

For edumacational purposes: crackle glazing most likely didn't begin as an intentional effect. It's actually tough to formulate a glaze to a clay body so it "fits". If the clay body or the sources of materials for the glaze change, as is likely over time as mines change, it might knock a glaze out of fit. Nowadays we have the science to control or correct it, so we get crazing when we want it and avoid it otherwise (potters in the US seem to dwell on the cracks harboring bacteria and thus avoid crackle glazes for functional pieces, but you'd think the Chinese would have abandoned crackle glazes long ago were that true).

[bearsbearsbears]

However if one is lucky, the inside of the cup may end up with pattern similar to this {cut image}

A more serious concern is that crackle glazes can compromise the strength of a piece. It's been noted that crackle-glazed pieces are up to four times more likely to break or chip than non-crackle glazes.

Yixing with glazed interiors often break. I had two such gaiwans split in two in the middle of brewing. Were it not on the tea tray when it split, I might have burnt myself or my guest or ruined the finish on the dining table!

[edkrueger]

I'm glad bears has his priorities right.

[bearsbearsbears]

I'm glad bears has his priorities right.

gongfu brewing teaches you not to cry over spilled tea

[beecrofter]

differential thermal expansion
I had a vendor cheerfully replace 2 glaze gracked gaiwans that were glazed zisha after a long period had gone bye when I asked if there was something missing in my care of them.
What was your source?

[Smells_Familiar]

something to keep in mind also is that often times glazes will have cracks in them that are very hard to see before a stain develops. so my new hagiyaki guinomi had cracks in the glaze that were very hard to spot when it was new...i saw the cracks though because I'm anal and inspect things way more than most (it's educational )
only once i used the guinomi for sake and tea many times..did the cracks appear darker. actually, tea stains very well...once it was intruduced to the guinomi the cracks developed stains in them...this is the point the casual user would notice them.

my unprofessional hunch is that it's rare to find a glazed piece that doesn't have a crack in the glaze somewhere.

[Intuit]

This is a product quality control issue related to improper clay preparation, uneven heating during firing or poor glaze technique. Given the very short period of use, I would go back to the vendor and ask for a replacement, supplying photo evidence to back up product failure claims.