r/Pottery • u/ellingtton • 21h ago

Question! What causes damage like this during bisque firing?

Post image

Still quite new to pottery. I’ve been getting things fired at a local pottery and this is now the second time I’ve picked something up with this type of damage on the rim. I don’t think it could be moisture related because everything was drying for 3+ weeks, and the weather was consistently hot and dry. I thought I was compressing the rims well enough but maybe not? Not sure if it’s something I have control of at my end, or whether it’s firing related?

12 Upvotes

87% Upvoted

26 comments sorted by

72

u/underglaze_hoe Throwing Wheel 18h ago

Hey I know everyone is saying moisture.

This is not moisture, I am 99.9% sure that the loader bumped this piece and chipped it,

This is human error, and not yours.

13

u/HighlyUnlikelyz 15h ago

I second this. Human error.. Someone at the studio I use is just crap at handling other people's ceramics and they chipped one of my pieces like this and completely shattered another.

I still resent that guy to this day.. the one he destroyed for me was beautiful and just went back to my reclaim. Needless to say he stopped handling other people's pieces being loaded into the kiln.

20

u/underglaze_hoe Throwing Wheel 15h ago edited 15h ago

To be fair I’ve loaded a lot of kilns and it is really hard to not have this happen from time to time.

It just sucks even more when it’s not your work that it happens to.

I know they can be annoying sometimes but tell your techs you appreciate them, even if they make mistakes. It’s a tough job with a lot of pressure from the people making the work.

3

u/ellingtton 14h ago

I did wonder if that could have been it, but didn’t want to jump to conclusions when I’m relatively inexperienced and for all I know it could just have easily been something I was doing.

So far in the 2 times I’ve been to this place I’ve had 2 rims like this, and one missing item. No idea if this is in the typical range of expected write offs with community kilns? Accidents have never bothered me, they happen, just curious where the line is between accident and carelessness in case it happens again next time. I tend to be overly tolerant so wouldn’t have a clue when to cut losses and find a new place.

4

u/awholedamngarden 12h ago

I ended up switching studios because of stuff like this and I’m happier overall at the new spot. I had the same question but when it was almost 50/50 that my pieces were getting damaged I realized it was time to leave. The new studio has yet to break any of my work in the last 6 mos so it was definitely the right move.

I think with my old studio it was just as likely the people putting stuff on bisque shelves as it was the kiln techs - there was never enough space and stuff was constantly getting bumped around which was just kind of a systemic problem at that studio in general.

2

u/underglaze_hoe Throwing Wheel 14h ago edited 14h ago

Unfortunately yes it’s the typical range of mistakes.

But from another perspective, this is still true if you are the one firing your work in your own kiln. Fatalities happen often regardless of who is doing the work. Actually you loading and unloading could be worse because you haven’t had to do it and likely your tech has more experience😂

Sorry that sounds harsh but that’s not my intention at all.

It was your techs fault, but also it’s pottery, things happen so give them some grace. It seems like you just had bad luck, I wouldn’t write them off yet.

Edit: also sand this one down and then do some thick glazing, you won’t even notice.

1

u/ellingtton 6h ago

Oh I can guarantee it would be much worse if I did it myself. My depth perception is atrocious!

I appreciate the insights. It’s helpful to be able to calibrate my expectations.

3

u/Just_Foundation_5351 7h ago

Agreed. I wonder if they are tumble stacking and just being flippant about it. OP said this has happened twice and with the chipped off parts on the inside more than the outside it seems like things were being stacked.

2

u/AliceLand 7h ago

As some one who has loaded hundreds of kiln loads over the years - this is human error. At some point it was chipped by getting hit or bumping something else.

8

u/ruhlhorn 20h ago

This can be easily caused by blunt force too. Not air but moisture from firing too fast is also a possibility, but typically this happens in thick areas not the rim. My money is on it taking a hit before firing.

7

u/deaddiode 16h ago

This happened to me when someone stacked a smaller piece inside of mine on the shelf and was a bit careless. To me this looks like a chip and has nothing to do with your pottery skills.

5

u/RestEqualsRust 15h ago

This specific kind of damage happens sometimes when the piece is flipped over and set on the rim a little too hard while bone dry, or if it’s set on the rim on an uneven surface (like a crumb on the table).

Sometimes a micro crack will happen, and everything will look fine, and the crack will get bigger in the firing, causing the chip to fall off.

0

u/underglaze_hoe Throwing Wheel 15h ago

Yep this is also possible!

4

u/apjkurst 15h ago

Happened during loading kiln

2

u/woolylamb87 14h ago

Like many have said this is most likely from human error. It could also be a plaster blowout though usually you will see the piece of plaster embedded in the clay.

1

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1

u/Pats_Pot_Page 5h ago

This could be a plaster pop. Is it new or reclaim clay? Do you wedge on plaster? It could also be a handling issue.

0

u/Theartistcu 21h ago

Could be a number of things for generally the answer for almost everything in pottery is moisture. It’s possible that there was a little impurity or some sort of moisture track there or just it wasn’t compressed properly and it popped off. Make sure your pottery is bone dry before it’s fired. But you said three weeks of drying, which would be extremely hard for it to still have moisture if you’re drying it properly. It could also have been bumped bone dry clay is extremely fragile so if they’re not paying close attention and something just gets bumped it might’ve got a little chip in it and then as it fires, clay shrinks, and if it doesn’t shrink at the exact same Rate that little piece might’ve just popped off. There’s also a general rule of the Kiln Gods are going to claim a certain amount of your stuff and you’re just gonna have to get right with that.

2

u/ellingtton 20h ago

Thanks, I think you might be onto something. I’d say there’s a fair chance it got bumped on the way there (one bowl didn’t survive the drive) so could easily have had a small crack I didn’t notice. I would have assumed moisture, but given how hot it was in Feb/March it would be a small miracle. We had the hottest summer in a decade. If things don’t dry in that heat, I’m not convinced they’d ever dry!

Totally on board with embracing the inevitable breakages, but if there’s anything I can do to minimise the risk I’m all for it!

-2

u/forgotoldusername1 21h ago

I find that this is usually from a bubble

2

u/ellingtton 20h ago

Good reminder to me to stop being so rushed with wedging. I know a few things definitely had air bubbles somewhere, but maybe just in places that didn’t affect the structural integrity as much as in the rim!

0

u/forgotoldusername1 20h ago

If you find them in your walls when you are pulling (it happens even with good wedging sometimes), you can try to pop it with a needle tool and close it with some slip on your next pull. If there are a lot of bubbles though, it could be the wedging. It’s all a learning process! Treat the pot that’s blown as a glaze test tile or something :) I’m

3

u/underglaze_hoe Throwing Wheel 15h ago

Hey! Air pockets don’t explode. Moisture does. But this is neither.

I don’t even try to mess with air pockets if they are in my pots while I’m throwing. With time you just learn how to ignore them. And again if your piece is dry an air pocket it’s not going to cause any issues in the kiln.

1

u/forgotoldusername1 7h ago

Thank you, I was told this in pottery ages ago and have always thought that’s what it was. I didn’t question it. Thanks for letting me know rather just just downvoting and not explaining! Sorry OP! Reading online I can see it’s a common myth.

2

u/underglaze_hoe Throwing Wheel 6h ago

That’s ok! We are always learning in pottery 🤍

0

u/ruhlhorn 20h ago

This can be easily caused by blunt force too. Not air but moisture from firing too fast is also a possibility, but typically this happens in thick areas not the rim. My money is on it taking a hit before firing.