Will this BLOW UP in the Kiln?? Do air pockets in clay matter?
Vložit
- čas přidán 12. 05. 2019
- Pottery Mythbusters!
This video we are testing if air pockets are the reason that clay sometimes will blow up in the kiln or if it is actually due to moisture in the clay.
Mocha Monkey and Pottery Studio: Send me stuff or visit @
Jonthepotter
115 South Olive St.
Waconia, MN 55387
ALL THE THINGS;
***PATREON - If you want to support me financially, head over to the Patreon page
/ jonthepotter . - Pottery Giveaways every MONTH! Your support helps me to make MORE videos, BETTER videos, MORE pottery, and BETTER pottery!
***ETSY SHOP : www.etsy.com/SHOP/jonthepotter
***WEBSITE: www.jonschmidtpottery.com
***INSTAGRAM: / jonschmidtpottery
***FACEBOOK PAGE : / jonschmidtpottery
MY KILN : amzn.to/2Ibfu2X
METAL SCORE AND TEXTURE TOOL: amzn.to/2BbyNEv
SCULPTING KNIFE TOOLS :amzn.to/2KNzkiV
BEST THROWING SPONGES : amzn.to/2Uk2nTr
NEEDLE TOOL: amzn.to/2ri67DU
BEST TRIMMING TOOL : amzn.to/2UEBjgS
BEST WIRE TOOLS : amzn.to/2D3cTDE
MY CAMERA: amzn.to/2UkzmHc
The BEST lens for photographing pottery :amzn.to/2QRtxeA
LIGHTS :amzn.to/2UbeWg6
My WHEEL : skutt.com/products-page/potte...
CLAY AND GLAZES: continentalclay.com
Honestly I don’t think I could resist just yeeting that ball at a brick wall 🤷🏻♀️
I am really impressed that the hollow ball did not crack due to the shrinkage during the drying process. o.O
I thought so too! Like, how did it not crack?!
the air escapes so there is no pressure build up, allowing shrinkage without fracturing.
@@theslenderchick1797 - the air escapes so there is no pressure build up, allowing shrinkage without fracturing.
@@bungawarrahlima8816 I am a ceramist, I know how it works, but my question is more of how did the air escape if there was no hole poked (Yes clay is porous but there is no large area of escape.) I am just assuming that it was because he preheated it for so long and thus slow fired it.
You were talking about the drying process, and that is what Lima commented on. Air can escape freely during the drying process, no holes needed.
Just recently found you. I love your upbeat personality and approach to teaching. Thank you!
I appreciate the “myth busting “. I’m 4 years new to pottery, and these help expand my mind!
Weeee!! I saw my name in that thread screenshot! ;)
Mine was about a social myth; The "hand builders aren't as good/skilled as throwers", which drives me nuts. I'm more of a thrower than a handbuilder, but I see the value in both skillsets and methods. :D
Would the closed orb survive the glaze firing?
mike robles yup
Wares can't exlpode, after the first firing, as they have no water to cause the explosion. They can crack during the second firing, but that is usually due to a glaze fit issue, or a previously unseen stress crack appearing.
@@benpatterson4452 i would disagree because when the clay becomes vitrified its no longer porous and if the temp is still rising it may cause it to explode, but @jonthepotter needs to settle this!
@@josephbrazda5664 You're right, during the glaze firing, the body will vitrify, making it so nothing gets in or out. But that doesn't matter, for a couple reasons. One, there will be little to no air in a sealed, bisqued piece. Some of it left, during the bisque, and there isn't a lot of pressure to push any back in, porous or not.
Second, air only expands 1.5 times, in a firing. Water expands 1700 times, hence the problem with damp wares.
Yes it will.
Thanks for doing this. I’ve done the hollow experiment in the past at the prompting of my pottery instructor. I dried it for well over two months ( NC has pretty damp weather at times) a few week too after glazing. Still have the piece!
Try air pockets within the clay. As you do not wedge clay enough when combined remnants.
Liz Moyer I've done that. It fires just fine!
Air pockets in the structure, are just weaknesses. The will mot explode, if dried thoroughly.
Provided there's no significant moisture or that, like Jon did, you let it dry for a long time using a pre-heat, it'll be fine. The air pocket doesn't care, it's the water expanding inside an air bubble that can cause the issue.
I did a pit fire recently and my piece shattered due to heat shock. One of the cracks revealed a small air bubble in the wall of the vessel. The piece survived a bisque firing just fine, so that shows that air pockets don't cause pieces to explode.
This is interesting, but doesn’t say much about the socalled “myth”, since you fired so slowly. Would be more interesting to try it out with a regular firing, since that is what most people mean when they say ‘will explode in the kiln’. You just basically stated that it doesn’t matter, but I still believe that there is a good reason to not fire work that is too wet or has air pockets. This is not a myth!
Itll obviously explode if u fire it fast. I thi k the myth is that you cant make a pot if it has an air bubble in it
Agree 🤷♀️
@@illicitlegacy3783 We get that's what he means, but only because we have experience with it. The video title contains the question "do air pockets in clay matter?". And yes, air pockets matter.
What about clay that is thicker than your thumb? My teacher never fired something if it was too thick.
Emily Sims I’ve fired clay thicker than a thumb but doing so is riskier because it increases the likelihood of having an air bubble. If your clay is good and wedged it’s generally fine.
Emily, that clay ball could have been fired on fast and done just as well but the mugs had to be fired very slowly until they were dry. As far as firing thick things they can be fired super thick you just have to go slower through the chemical water stage water stage (550° 1150° approximately) I have actually fired a sculpture of a head that was close to life-size that had no holes drilled in it it was totally solid. I dried the piece out in an oven slowly working my way up to 550° for 12 hours and then I put it in my kiln and fired it on slow, no cracks no problems.
Air bubbles never cause blowups, ever, promise ; )
Thicker wares, just take longer to dry, and that causes the issue. As a teacher, I won't fire anything, thicker than an inch, unless it's hollowed. I could just fire thicker things slower, but I fire at a rate, that works best, for the majority of the work, which is thinner . Slowing the kiln down for a project or two, is just a waste of time and energy.
Almost anything will fire fine if you candle for 8-10 hours like this fella did.
Thanks for all the responses to this question, yes it can be thick it just has to be completely dry and/or fired very slowly. Even if sometimes it seems totally dry it might still have moisture in it and if fired at a normal pace may causing problems. But yes to all these other responses!
9pm
I’m going to sleep early tonight!
1:05am
Will clay with air blow up -_-
Fascinating tho 😉
Great! How about Going straight to glaze and missing the bisque?
A lot of people do that
its called single/once firing! Simon Leach has great videos on the technicalities of it
There is a risk of the glaze bubbling if organic matter burns up during firing.
Most ceramics factories in China do single firing
Englishblue
Lost 3 trees that exploded. They were hollow. Maybe I fired them too quickly. 🤷 You should drill holes in the orb and make it a cool salt shaker.
Yeah, they might not have been completely dry.
Thank you for this, very helpful. I look forward to more debunkers. Yay!
"This video we are testing if air pockets are the reason that clay sometimes will blow up in the kiln or if it is actually due to moisture in the clay."
The air pockets hold steam which is trying to escape quickly....
It's the air pockets trapping the moisture that's trying to escape. If you fire really fast the steam will blow it. A slow fire will let it escape slowly.
It's not the air pocket or the moisture, it's a combo of both fast fired that makes it blow.
-----
Do the same thing in a 2 hour fire it will blow.
Great! Also hope you can try glazing still-moist greenware and doing single fire at some point though that might be tricky with dipping vs. brushing. I also think the 'cool to the touch' theory is bonkers. In humid central VA my pots can sit for months and still be cool to the touch and deemed too wet to fire. Preheat is a great insurance policy against blow ups.
Some potters make a living, single firing. I will likely, never been one of them. It saves time and money, but there is a lot that can go wrong...
I understand your view of feeling the ware's temp to judge wetness. I've talked to other potters about this, and apparently, there is a noticeable difference between "Cool" and "Cold"...
Have a look at ‘Single Firing ‘ F/B page.
Thanks so much, this will help me a lot with my school clay projects! I always let the students work dry forever, just to be on the save side... :)
Congrats on being Creator on the Rise! This is making me want to learn pottery
S - cracks and compressing the base of various shaped ware would be a good topic to explore Jonthepotter. I like your upbeat presentation style btw.
Excellent! So great to know. Will proceed a bit more fearlessly. 😁 Thanks Jon! ❤️
Just found you on my timeline yesterday and I can’t stop binge watching your videos! Loved this one!
Very cool! So glad you tested these two clay bugaboos. You didn’t even have to bore tiny holes in the sphere! 👍🏼
Love this. Defiantly do more
Brand new to pottery here..haven’t jumped in yet but these videos are great at lighting that fire. Patreon here I come lol
Jon,
always good to see it happen...not. I single fire raw glazed pots in a manual kiln with no way of knowing the actual temperature.
Tempting blowups with each firing is not good with glaze involved, have a wee backup kiln if it happens.
I weigh my pots on the gram scale and when they stop losing weight I put them in the kiln and set all 3 switches to low for 2 hours. As I type the kiln is on it's 10th. single fire and so far so good....will find out tomorrow morning.
Enjoyed the video...thanks for sharing.
Thank you so much for do this! It was so helpful for me and a new teacher!
I've loved your experiment!!! With low firing you've got it. Thank you so much! You inspire us 🌞🌟⭐☀️⚡🔥👍
The little orb is cute, it can just be a decoration or paperweight!👍 Can't wait to see it and the donut decanter glazed!
Your videos brings me such a great news since I need to fire thick figure and so afraid of air pockets I might created during sculpting. Your channel is awesome!
I will admit, that I played a role, in the propagation of the " Air pockets cause clay projects to explode" myth.
I repeated it, to my students, because that's what I was taught.
It wasn't until, years later, that I learned the truth, and began stating such, to my students. The truth is air on increases in volume one and a half times, when heated. Water expands over one and a half *thousand* times.
Air pockets are still, definitely an issue. For one, they are a weak point, in the structure. Anything is stronger, than an empty void. Air pockets also trap moisture, which can, and does cause explosions.
The candling/ water smoking, that you did, was beyond overkill. I do a four hour hold, during bisque, and that's with a lot of uneven, thick wares. I rarely have issues, with this program.
Your damp greenware survived easily, because the program was so gradual. To further ensure that damper wares survive, put them in the kiln, top or side up. The bottom is the likely spot to explode because it is thicker there.
It looks like you are enioying your "Do All" trim tool.
You covered the biggest myth, in Ceramics. I really can't think of any more.
I just stumbled on to your page and love it!! Funny thing is I think I have two of your Minnesota mugs. Awesome work, can't wait to watch more videos.
Very cool idea for a video! Would you mind also glazing the sphere?
loving the new marble stuff
Great video! I'm learning tons from watching your channel. Wondered whether I could ask which model of Skutt kiln yours is?
Thank you. I heard it was a thing. My art class will be fuming
l am a newbie to the world of pottery .. have only taken three classes but have been bitten by the bug now all l do is watch pottery videos .. l am learning so much and thanks for the two Facebook pages you turned me on to .. l hope they accept me! You rock Jon .. thanks!
Enjoyed your myth busting video......Very informative.
Ha! When I took ceramics in college me and my teacher literally drilled a hole on the bottom of this turtle with a tree on top that I handbuilt, and we drilled a hole in it when it was fired already. Not glazed at all yet. 😂 it took us a few drills and one actually broke trying to drill into the turtle.
POTTERY HEADS AND CLAY BUDDIES SHOUT OUT!!! WOOT!!! :)
hello, it is my first time watching your video and I love it！please make more videos teaching hand building pottery for beginners!! thx :)
Thank you. I've been trying to tell this to people for years!
Thanks for that. It was an interesting video. 👍🇬🇧
I'm not sure if I'd call it a myth, but a lot of people say earthenware is not good for dinnerware. I know of a few famous potters that use earthenware for mug, plates, etc. and I've heard some good arguments about why it is ok to use. I've never seen any test that proved it's not good for dinnerware. It seems like a touchy subject.
Can you make a video about how you glaze your pieces?
Excellent video!
Love your videos. My wife and I have been building a small studio in our garage and I'm always keen on new equipment and ideas for pottery. What is that digital control panel add-on you used for your Skutt Kiln?
I think it's this: www.cromartiehobbycraft.co.uk/Catalogue/Ceramic-Kilns-Electric-Kilns-Pottery-Kilns/NEW-Touch-Screen-Controller-Upgrade-Kit#.XNwRsvfTU0M
Hello Jon the Potter... Iam so happy I stumbled into your video... And that's because I have recently got some clay and tools.... My son and I are so in love with playing with clay.... But sadly every project is blewn in the Oven.... Do have any advice how can I burn pieces safely at home?
I think that is cool !!! How many different classes can put together ?? Just a question ,, for my future artistry vision .. 😊
I've always wondered if there was a way to completely glaze something, like that orb. No unglazed areas. Would those stilts work (they look almost like a miniature bed of nails LOL)? But wouldn't the points leave holes in the glaze? Enquiring minds want to know!
my hollow forms always crack in drying if i dont poke a hole. what did yoy do slow dry?
I tried a class project or two where I tried to get a water effect in the bottom of a ceramic piece with a (very) thick layer of translucent glaze, but it cracked like no other as the instructor warned it would. Does this happen always, or would it be possible to fire/cool slowly enough to let the glass form an uncracked layer?
You are so inspirational 👾
how often do you fire your kiln and like what's an estimate of how much it costs to fire an electric kiln ? O:
Oooooohh very interesting! Still makes me super nervous to fire things that wet! What about a single glaze firing test? I've always been interested but too chicken to try it!
I LOVE MYTH BUSTING IDEA!
Love the video idea!!! So what temp is the preheat at? I have a manual kiln that I put on the bottom elements, an hour later the next level up, then the 3rd level.
I do this too, and when I want to heat up even slower I prop the lid open higher at the beginning. It's a lot tougher with a manual kiln but I haven't had any explosions in mine (knocking on wood now) :)
oh my God! This is soooo amazing 👌
As always an awesome video, I’ve learnt so much from you, also pottery heads and clay buddies. I’ve nothing to add to what others have said except that maybe you should get Ryder a trampoline! 😂 he’s so gorgeous!
Do you think you could throw a mug blindfolded? Or throw two mugs at the same time blindfolded?
Jon, this is Sherio the potter. Firing ware that is wet is very hard on the kiln elements. Replacing elements takes time and is expensive. As for air pockets being a problem that is a myth. It’s water that turns to steam at 212 degrees that is the problem. I always pre-heat sometimes over night at 200 degrees. Get the ( dry )ware toasty dry before slowly firing through 1100 degrees for best results.
one of my pots totally exploded today making a total mess inside the kiln .. it literally turned back to dust :D :D ... the pot next to it remained unbothered . :D I went a bit harder with completely wet clay .. will nto do it again :D
I have a question about glazing and wood firing kilns. Will a piece blow up if it is set on top of a wood firing kiln to warm up for firing if the glaze on the bisque piece is not fully dried?
Wow! Ive always wondered about that. I actually just made a dragon egg similar to how you made that ball. I ended up putting a hole in the bottom just to be safe. I wonder if it will explode when it goes for the glaze firing.
Hi John! Thanks for your fun informative videos! I would love to see some experiments done with firing leaves... marbles or different colors and basic combustibles... and or experiments with soda ash silicas and oxides etc... That always fun to see!
It isn't a good idea, to put combustibles, inside an electric kiln. There is the issue of fumes, plus combustibles will greatly shorten the life of the elements. This is why potters use designated kilns for soda, salt and Raku firings.
I've heard that it's not the air pockets that blow up, but it's the wet clay. I've been too impatient and learned my lesson. I have a manual kiln. So not able to slowly heat up. .
By the way, I love my Tumbler that I got from the kickstarter
Música jibara
Hi, haven’t found many videos about converting a kiln sitter to digital. Just bought a second hand wheel and kiln. Kiln will need to be converted.
Did you pierce the ball during the drying process? If I don’t pierce my close forms they will crack for sure
I want to make some hand built little cottages. My first time making something. The main base of the houses will probably be 2”-3”. My question is can I make a solid cube and fire it or do I need to hollow it out?
I go straight to centering without coneing up into the phallic form. I don't think it necessary. I don't even make my clay into a ball before throwing it on the bat. I leave it a cube.
thats insane aaaaaa
Plant pot with matching drip tray in the marble and blue would be incredible....better yet a set of 3 of them in different sizes would be ahhmazing!! Wishful thinking 🙃
I didn’t realize you bisque fire to 06, I’ve always done 04 but I would imaging your glazing would go just a little faster because it’s a little more porous. I’ll have to try it out.
For stoneware I've heard of people doing anything from 08 to 04. Like you said it changes how much glaze your pieces absorb, so you will have to adjust for that.
I bisque to 08 and fire to cone 5/6 for the glaze firing
hey, What if you glazed that hollow ball? Glazing might make it airtight ---> make it explode?
I would like to learn more about refiring stoneware when glazing ( without cracks)
How about the purity of the clay you use? I create molds for tiles and sprigs and am always so worried about getting tiny pieces in my clay bodies. Would those impurities blow up your piece? Answer or test?
I have heard that plaster in your clay with blow up in the kiln yet I have seen folks drag a plaster slab across a concrete desk leaving remnants of the plaster and then wedge clay in the remnants and using it to make pots. So how much plaster in your clay is to much?
A little off topic, but I LOVE throwing round shapes! I love the complexity and how you have to really focus on that round shape so it does not turn to ovally, and focusing on the evenness of the walls.
Sorry, I just love that round shape 🙂
Awesomeness!
Do You have to fire sculptures twice if you are not glazing them. X
Hi what pottery wheel do you use?
When I fired my tap and die load I assumed my flasks would blow up, so I fired with the caps off and then with caps screwed on loosely. I didn't have a problem but I know if clay is wet and thick it will explode in the kiln. And any bit of plaster I'm pretty sure explodes too. Also, if you know where I can get a wide diameter coursely threaded stud press mold I would like to make a load of pottery thermoses.
Hello all! I was in a bit of a hurry to get some things fired to bisque before leaving. I did the same thing with leather hard bowls. Although, I did do to a cone 04. I did a slow fire to cone 04 with a 10 hour preheat. Unfortunately, I had cracking in both, so it didn't work for me.
0
But would they survive if you fired them how you normally fire everything else?
Tips on centering work for trimming?
I'm experimenting right now is how I found your vid. I'm melting glass over rocks in my kiln.
I use an earthenware clay body and do not wedge the scrap clay real well before reusing...I am sure there are air bubbles in the clay, and if I see them on the surface I will puncture them with a needle tool when making slab slump bowls or platters..I have had very few incidents of exploding, as the crucial issue is to make sure the pieces are TOTALLY DRY before firing...it's the steam factor that causes explosions...even if I feel the pieces are bone dry I run the kiln on low, and leave the kiln lid slightly open, for the first hour of firing, to ensure any moisture is out of the clay.
Hey Jon The Potter, I was wondering if you do workshops for college students? As an art major (double concentration: painting and ceramics with a minor in theatre), it would be nice to have you at our college to do a workshop!
It is the expansion of trapped water vapor into steam that causes breakage. If there is little to no trapped water present at the temperature where it turns to steam, the clay will remain intact. Chemically bound water in clay will not turn into steam because it is driven off at higher temperatures than molecular water. Slow forced drying below the steam point reduces the chance of breakage compared to not candling, but is only advisable for certain bodies and types of construction. A porcelain body, or a vessel with wide variation in thickness, might not explode by candling for 10 hours, but it could crack due to differential shrinkage of thin and thick parts caused by uneven drying. This is the main reason against force-drying of ware--you don't want to increase the chance of uneven shrinkage and cracking, only to find out your bisque has broken. So, I think it's fair to say that the answer to the question really depends on what clay you're using (e.g., grogged versus non-grogged bodies) and the complexity of construction (e.g., are different parts liable to dry at different rates). For what it's worth, I've seen very thick pieces survive the bisque, but then when glazed, the bisque soaks up so much water that it cannot escape the bisque fast enough--and it explodes in the glaze firing, which is far worse than a bisque explosion since the fragments will adhere to adjacent vessels.
Basic physics.The myth is that trapped air expands with the heat and blows the pieces. Though air does have a % of expansion when heated (+ compression) it's marginal in ceramic firing : remember the ceramic body is also expanding at a much greater ratio. It would take far higher temperatures that those used in a ceramic firing to make the air expansion enough to blow a piece. However, WATER molecules expand quickly into vapour at a mere 100°C (boiling point). In fact the ratio of expansion for water is 1:1700. This means that a water molecule expands 1700 it's size at the boiling point! If there are no venting holes in a piece, the water vapour pressure cannot be released and the piece will blow. So dampness (even residual) in pieces is responsible for the majority of mishaps. Especially the tick walled pieces. Even if they have been drying for months there is still atmospheric humidity. Clay is hydroscopic. Always make a slow pre drying curb in the kiln before firing ; under the 100°C mark for a few hours (depending on size and thickness of the pieces and kiln load)
Other reasons for blow-ups : -negligent compression of clay layers. If you are sculpting and not compressing your layers adequately you may be creating detachment issues once the clay expands and contracts in the firing.
- impurities in the clay. Especially if you are using recupered clay. Unnoticeable plaster fragments from moulds and whatnot. Debris from the studio, etc.
- incompatible clays. Clays that have different ratios of shrinkage and deformation while drying and firing. Ceramicists that merge different clays in their practice (nerikomi as an example) need to be aware of this.
Could it be different for a manual kilns? 🤔 my first project just exploded
More science experiments please Jon the Science guy :D
Haha I just made a sphere in my wheel class a week ago but accidentally wrecked it on the wheel trimming it so I had to toss it. Kinda miss it... but what can you do, it’s the risk of ceramic pottery making
Will it blow up during the glaze firing?
Just joined the groups!
Wondering what happens if you glaze the ball :) I'd imagine the glaze coat will be a little less forgiving.
I have had items "blow up" it was more of a shatter in place kinda reminded me of a car window, and it did have a pop when it happened. I am not sure of the cause however my theory it i heated it to quickly. Im still new to pottery so there's that as well. However, I am progressing well and I have not had an incident like that since the first few firings.
Im pretty sure the issue is with unknowingly firing compromised pieces normally. Of course its not going to break if you take two days to fire it, because you're just drying it first.
Maybe you could give away the glaze sphere and some kind of contest but that was really cool watching that experiment
In sixth grade at school, we had a pottery group and it was awesome. And I made a really cool garden gnome... And it blew up in the kiln. I don't know why... We were also taught to avoid air pockets and always poke holes into bigger chunks to avoid air pockets. I don't know, maybe the clay was too wet or something. I just put so much work into it and it blew up. I got to keep the head... until my dad broke them :D
i was told that if any plaster from the wedging table got in your clay it would explode. also if you clay is real thick in one area and thin in another it would blow. also throwing of the hump and not compressing the bottom back to the center causes the dreaded s crack