How to prevent 8 common cracks
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Do you struggle with cracks in your pottery? Nothing is more frustrating than making a whole kiln full of ceramics, only for half the pottery to turn out cracked. In this video, we are going to cover s-cracks, crazing, and more, so you can diagnose exactly what is causing cracks in your pottery, and how to prevent them in the future!
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0:00 - what causes cracks?
1:30 - the 7 most common causes of cracks
6:40 - what causes vertical cracks
7:40 - what causes shattered bottoms
8:50 - what causes s-cracks
10:30 - compression is a myth
11:20 - what causes edge cracks
12:20 - what causes shatter cracks (dunting)
13:10 - what causes shivering
14:10 - what causes crazing
15:20 - what causes springing & how I solved it
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I’m taking an into class and just got an S crack today on one of my fancy bowls. Forever will I be flipping my bowls!
I’m interested in this video but I was looking forward to another episode of “potting along with The Great Canadian Pot-off” or whatever the title is 🥺
Next week! I am filming right now and it's gonna be a good one :)
@@PotterytothePeople yes! Thanks for taking the time to reply ❤️
Oh, it makes a ton of sense that thermal stress could cause the walls and the bottom of the pot to pull away from each other, if they're retaining the heat differently! Neat!
Does crackle/crazing affect how food-safe the piece is? I once found a ceramic milk jug that looked like that, and not knowing anything about pottery, I didn't want to use it because I was afraid the cracks would make the glaze not work to protect the milk from the jug and vice versa. But I don't know if that's really how it works or not.
That topic unfortunately has no clear-cut answer! I talked about it a bit in this video: th-cam.com/video/X92zYEt0iVc/w-d-xo.html and also I like this article on the topic: www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiz1c3d4IWFAxW4VPEDHR9hDEMQFnoECB4QAQ&url=https%3A%2F%2Fceramicartsnetwork.org%2Fceramics-monthly%2Fceramics-monthly-article%2FTechno-File-Dirty-Dishes&usg=AOvVaw3poqL3p7uZBNOWUf3l2EN_&opi=89978449
I will be one among the people that you said is going to scream: COMPRESSION, COMPRESSION, COMPRESSION!!!!
Anyway, I love your work and your videos! ❤
Love from Brazil 🇧🇷
First, it's a great channel, and I really enjoy your videos...Thanks so much...!!!
Please do a video on the "compression controversy" so we can better understand what you mean. "Compression in clay bodies" and "Ceramic Compression" are not only a reality, it is a field of study, as well as, a diagnostic tool used in evaluating clay bodies. Clay...IS NOT...a liquid, though it has some of those characteristics. A simple search (if interested by anyone) in clay characteristics from a material science perspective will give you more details and understanding...
Empirically, if it were a true liquid it would not need to be wedged/pugged to remove air, thus it also has "compressive characteristics," unless, in this case, your meaning of compression is something else entirely...
Interesting to hear your perspective! I have spent a big of time googling around and I am getting VERY different answers depending on the source. I am not sure it's as clear cut as you say, but I can only speak from my own experience. Really interesting to hear your thoughts.
@@PotterytothePeople I think (perhaps?) the differing information you are finding could be generated from the "lay side" as compared (perhaps?) to the material science side and how clay behaves structurally. I look forward to a video where you can explore this in more detail and share what you have learned from the different sources. Thanks again for all your work in sharing these videos. They are EXCELLENT!!!
WOW I have never seen somebody make something up and pull it out their ass as extensively as you. Compression is a myth, if compression mattered slipcasting would be impossible.
@@StuninRub O.k. if compression is "a myth," then why can it be measured?
Maybe go back to school and learn something before you get more confused than you already are from watching videos you don't understand or ones that provided poor information because there created by D.A. that are only DIYing themselves clicks and like...or...are more interested in "trolling" with sarcastic comments than they are of learning something...
On a more positive note, on the off chance you actually like to learn, here is just one example on countless studies to learn from: "Parametric study of the diametral compression test for ceramics." Plenty out there to read about or just Google "Ceramic Compression Testing." Clay body characteristics (which includes compression) is critical to fully understanding how a clay will perform and behave. Do you need to have a clay tested? Of course not, as experience will teach what and how to use it...That does not mean compression in a clay does not exist or effect its behavior...IF...you understand it properties...Good luck if you take this as a positive challenge, or you can just remain obtuse...It is a choice...
My art teacher and I love your vids! Pottery will always be an art form I practice in my life thanks to you both. Thank you!💜
Thanks for watching!
I appreciate your channel. I'm a beginner and have learned a lot from you!
Awesome!! Thanks for watching :)
Hi Mia, just a little greeting from The Netherlands. I enjoy your videos very much. I sort of envy your resolve, when you encounter certain problems. I hope I can take that away for my own work :)
Thanx,
Karin
Thank you so much! You can do it :)
@@PotterytothePeoplethank you :)
I love your videos! You explain things in such a straightforward and clear way. Cheers from Uruguay ☺
Thank you very much!
Always love your videos. A while back in a video you spoke about covering pots with attached bits. Since then I have always done that and never had another problem. THANK YOU.
love to hear that!! ❤️🙌
Another great video, thank you!
Glad you enjoyed it!
This is so helpful! Thank you for sharing your knowledge!!!!
Oh Cracks... you are caused by stress... but if only you knew how much stress you cause... 😂🎀💖
haha true
Hahahahaha 😂😂😂😂 I'm gonna say that to my pots! 😂
Thank you once again for the great information!
yay! I'm glad you liked it!
When we switch our clay to a softer, wet clay, not much grog, pretty smooth clay, let’s call it AP, and did pottery one off lesson. I saw many cracks at the bottom. Then I started to focus on compression not leave the water in for too long and the cracks has decreased. After make a piece we wire it and heat gundry it then paint it with UG or HF right away on greenware. So far okay la,
I’ve been drying pots on bats for over 15 years and have never had an S crack (actually have never had them for any of my ware). But I do make sure I compress my bottoms and also ensure roughly even walls and bottoms. One possible tip for bats: for large pots, I flip them upside down - with the bat still attached - when they are firm enough to do so. But mostly I let them pop off right side up.
I always watch video about your pottery, you make it beautiful 🎉
I don't know, I never flip my pots and I have no trouble with s-cracks but, I compress my bottoms when I'm throwing them.
I've seen that it makes a big difference when throwing off the hump.
Interesting!
COMPRESSION, COMPRESSION, COMPRESSION!!! ❤🎉
Same, I use a bat system + compress the bottoms. Never had an S crack.
Not me thinking you said ass cracks (because of the bottom cracks) the entire time untill 9 minutes in haha! Newbie here, learning a lot :D
Ilysm!
❤️❤️
This video is so helpful, especially since I recently purchased a kiln and am learning as I go. Are pinholes also caused by similar issues as with cracking?
Glad it was helpful for you! There are a couple of things that can cause pinholes. Here is a great resource on the topic: digitalfire.com/glossary/pinholing
I read the article you referenced which explained things well. My kiln is a Skutt 818 and so far I’ve only used Laguna B mix, bisque to cone 04 and glazed to cone 5 at Medium speed. I think I will try a slow cool to see if that helps. I’ve read different opinions about food safety with pinholes and would like to know your opinion. Again, thanks so much for your videos and suggestions. I’ve been watching you since Covid which parallels my home studio work from hand building, wheel and recently kiln. You have a great way of explaining things and do beautiful work as well!
I've been a wheel potter for about 11 years and I never have had any cracking problems till I recently started throwing porcelain off the hump and have been getting s cracks in very small lidded jars. While I agree with your stance on compression, I do get better results off the hump if I compress the bottom. I'm wondering if this has more to do with just paying more attention to the water there than actual compression. What are your thoughts?
This is awesome! i have a question though: so you don’t use a bat system at all? I find it useful for some shapes that I would otherwise ruin trying to get them off the wheel head/bat. Thank you!
I have the same book, it is very good, thank you!
As I commented in this thread, I’ve been using a bat system for 15+ years with no issues. And I know other professionals who use them with no problems. I suspect cracking is due to the other issues pointed out in the video. Also, I DO compress the bottoms.
@@KarenTottenCompressing the bottom does nothing, as long as it is even and dries consistently with the rest of your pot, it wont crack.
Hi. I assume the cracks happen during glaze firing ?
If the cracks happen after bisque firing, can it be covered later on by adding glaze on it ?
If the glaze shrink more/faster than the clay, that would introduce compressice stress, right? Isn't that something ceramics can withstand well? Or is the difference between surface stress and internal stress in the clay itself enough to induce internal cracks as well?
I learned that the problem with ceramics is tensile stress, not compressive, that's why i got curious
I threw a large platter and used sgraffito to decorate it. It was beautiful until I put it into the kiln for its bisque firing. I just took it out of the kiln, and it was cracked nearly in half. I was so sad. How can I keep my sgraffito plates from cracking? The decorating method creates uneven surfaces and thickness, so it seems at least to me that I am lucky if it doesn't crack. Do you have any suggestions?
Thank you! I’m struggling with a porcelain-like cone 6 white clay. I keep getting edge cracks (on the inside especially) and shatter cracks at drying stage. I don’t know what to do.. I don’t think my walls are particularly different in thickness than my bottoms. Would you ever consider doing some one to one video mentoring sessions on this topic? Thank you
Are they drying too fast or drying unevenly?
I find it hard to tell to be honest...@@triciac1019
I'm not quite sure how to tell to be honest@@triciac1019
Trying desperately to figure a way to say this without challenging the kiln gods or clay… The kiln is unplugged and none of my clay seems to be paying attention to me at the moment. So I will try this.
My experience with stoneware is similar so far (quite a few years). Porcelain has been a bit different (yes, big surprise). I have found nothing to be 100 or even 90% with it, but working the bottom does seem to help. Compression is not a good word for it though. Applying ‘pressure' doesn’t seem to be the key, just lightly sliding my finger over it a few extra times does. (In typing that I realize that I also keep it dryer than stoneware, so the act of sponging it out more often actually lends to the argument to compress.) That being said, I haven’t actually tested by intentionally not doing anything to the bottoms of porcelain, but I think I have had equally bad results by not saying Bismillah when I close the kiln, or saying something it finds offensive, ((Whisper….) never say anything bad about the p word if it can hear you). It has never occurred to me to not flip anything to dry the bottom. Even if I had nice plaster bats I can’t see not flipping them. I am quite lazy by nature, but that is just taking it to a whole new level. Anyway, just wondering if you (or anyone else) has come across anything that seems to work consistently for you with porcelain s-cracks?
really interesting! I don't have much experience with porcelain. I think folks don't flip because they just never were taught to do it!
Regarding compressing, maybe what compression is really doing is forcing more water out of the clay and causing the clay at the bottom to have a uniform density/water content. You are just accomplishing the same thing a different way.
that is an interesting theory!
What the hell!!!!? Compression is rel!!!
Say crack one more time 🤣
forbidden drinking game 👀☠️
I'm just wondering how I can best prevent cracks in plates, as you cant take them off the bat to dry. Had two of my thrown places crack while still stuck on the bat this week a few days after trimming the sides and I have no idea what I did wrong ):
Did you wire them? If they're "stuck" to the bat, the cracks form from uneven drying.
The top and walls are drying and shrinking and the bottom is wet and stuck to the bat so tension forms from trying to shrink but not being able to.
I always run a wire under my plates once I've finished throwing them, but before they get put away to become leather-hard. Then I wire them again before I remove them from the bat to trim.
@@crowdedsubwaystation thanks for the tip! I'll definitely try wiring them next time, I was taught I shouldn't but your explanation seems very logical. Thank you
My next video will be about plates, maybe that will help you!
My first batch of pottery is currently in it's glost firing, so this could be very useful in a few days😅. I'm pretty sure the glaze is too thick (brush on glazing was not as easy as I expected)
Good luck! It's with the kiln gods now. 🙌
No cracks!!!!😁😁😁 I'm going to credit your previous video on cracking for that as I watched it several times before starting. Thank you!
I watched this the day I flipped my teapot over and the next day ( today 3/25/24) it was cracked lol. Live and learn
What exactly is compression?
sorry I didn't explain that very well! Lots of folks like to compress the bottom of their pots with a finger or rib.
@@PotterytothePeople I'm sorry, but to achieve what exactly? I'm completely in the dark about this.
Crack. We all deal with it. That's what my uncle said....
👍👏👏😘💚💙
Thanks for watching!