How to make pottery Food Safe, Microwave Safe, & Dishwasher Safe // It's all about Vitrification!
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- čas přidán 8. 06. 2024
- Making pottery food safe, microwave safe, & dishwasher safe are all related. It has to do with Vitrification. In this video, I explain everything you need to know about making food safe ceramics, and well as give you a deeper understanding of vitrification and how making sure your ceramics are vitrified creates food safe microwave safe, & dishwasher safe ceramics. Let's get into it!
//MENTIONED IN THE VIDEO
Digital Fire article on Vitrification: digitalfire.com/glossary/vitr...
Ceramics Monthly article on food safety of Crackle Glazes: ceramicartsnetwork.org/cerami...
Even more info on food safety with Crackle Glazes: digitalfire.com/article/crazi...
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//IMAGE LICENSING
All images are licensed (cc) Creative Commons. Attributions:
blue crackle vase
upload.wikimedia.org/wikipedi...
white crackle vase
commons.wikimedia.org/wiki/Fi...
flowers crackle vase
commons.wikimedia.org/wiki/Fi...
crazed plate
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kiln with people
commons.wikimedia.org/wiki/Fi...
mass produced mugs
commons.wikimedia.org/wiki/Fi...
//CHAPTERS
0:00 - intro
0:30 - other things that affect food, microwave, & dishwasher safety
1:35 - what is vitrification?
2:50 - testing for porosity
4:40 - how does vitrification work?
5:25 - why don't we fully vitrify all ceramic?
6:50 - is it safe to use ceramic that is porous?
7:35 - how does vitrification affect food safety?
9:45 - are crackle glazes food safe?
11:50 - fight me! or tell me what type of clay you choose :) - Jak na to + styl
So nice to have someone actually admit the issue and address it and not just say it's not a problem.
The moment you brought up porous pottery being used by humans for a very long time, that's when you got my subscription. This girl is real.
You can make earthenware pottery foodsafe by appliying oils to seal it, like food grade linseed oil. Simmilar to the way it's done with wooden cutting tables, plates and so on.
yes thats true! lots of cultures used milk even!
For this would you bisque then oil then final fire? Or what would be the ideal process ??🙂
Do you think a beeswax would work aswell?
Or just use food safe glaze on earthenware right?
@@nuclear15beeswax does work!
This video has given me a clear understanding of vitrification.... and what the issues are when it comes to certain types of glazes and food use. It all makes sense now.
I use porcelain from Kentucky Mudworks. I specifically use it exclusively because at cone 6 it is 100% vitrified with 0% absorption rate. It is very costly compared to stoneware from the same company, almost double. But I believe it’s worth it. I make pricey large pieces that in my opinion are art work that functions as everyday use. I wish more people understood that. I appreciate that you mentioned that porcelain is one of the strongest and safest pottery made (if fired correctly) thank you I found your video most enjoyable as well as informative.
This video might just be my favorite, and I don't even make tableware. Thanks for all the research and info!
aw thank you! i worked extra hard on it, so that means a lot 🥰
I know you are expecting a lot of opinionated comments strongly disagreeing with everything you had to say, and I can see there are a few "well actually" comments on here. Anyway, I just want to thank you for putting well-informed and balanced information out there on the internet. It is very helpful.
Thank you! That is kind of you to write :)
im borderline in awe with the way how you understand the pottery on the molecular level. this is the way to teach how it all works, that i was looking for, all around and found nowhere but here. Cheers from outside of the eastern border! ;)
i have been binge watching all your videos. this one made me think about the science and purpose of the science. i really appreciate it! thanks
Great information, thanks for putting this together! I use exclusively stoneware because I make mostly functional pieces. I fire to cone 7 as that is the upper cone of the recommended range for the clay I use.
Appreciate your perspective and transparency.
so happy that you addressed that article in your video! is the one i read months ago. science and history is there! i use earthenware exclusively for now as i’m a newbie potter, and definitely reduces costs when you just wanna make lots of pots!! anyway it is a great video :) lots of information, love your channel 😊
Great video and very level headed take on this topic
Thank you so much for the video! It's super helpful and easy to understand:)
Yesssssssss! Telling about vitrification myself to anyone I know who makes pottery :D Great video!
Thank you. Very informative and well reasoned.
so much helpful and straight to the point and great perspective on the whole subject , i myself hope to do pottery works like jewelry and rings holders and figurines, flowers holders , censers etc , but if i wanna make a food safety stoneware ceramics your video is one of top list to follow , the whole pottery world is rly wonderful to learn and experience .
glad it was helpful for you! ☺️
Great video….very useful information for passing on to beginners and refresher for hobby potters…thank you Mia
I totally agree about, your thousands of years argument. I am reaching projects i want to try and ways to get started cheaply
This is the video we needed! Thank you ~
yay!
Woah I just went down a Wikipedia hole wanting to know what vitrification even was on ceramics, googled my way to this, and it was way cool. Thanks!
You made a very informative video. Well done!
Loved the video! I'm learning new skills. Your video explained everything so simple! Absolutely a new fan over here :)
Btw, started looking for info cause I broke a cup this morning, lol. I believe "fixing" things at our time is a forgotten skill.
About the last section. I'm going to buy air dry clay. Maybe I'll build a kiln using bricks or mud. Is used in Pomaire (a countryside village located in Chile), that's well known for its pottery.
This was such a helpful video thank you so much!
Great video thank you, i was always confused and worried on how to check if my tableware is food safe and microwave safe
Thank you so much, this was really helpful.
yay! I’m glad to hear that :)
this video was so informative!
i use stoneware for all my pieces including sculptural ones, mostly because i don't wan o mix clays and i only have the means for one clay type at a time because i want to made some dinnerware pieces.
love the info! yes we have to watch out for lead.
My Grandma is a potter and I’ve been eating off both her earthenware and stoneware pieces my whole life without issue. I’m a potter now too and still happily eat off earthenware tableware but I personally wouldn’t sell it, mainly because I feel that stoneware feels more ‘sturdy’ to eat off.
I often use wild clay I’ve collected locally, but I definitely have to make test pieces to check the vitrification because I’ve had wild clays that don’t properly vitrify.
this is great!!! so helpful🎉
This video is avery good. I came to it with skepticism. I think that the cracking from water is from repeated thermal stress. I love the cultural aspect is really very good. I love the nuance about things. If you are looking for another video extending this topic, possible dose, solubility, oxidation states of colorants, how much could you possibly leach from a vessel.
I enjoyed it thanks.
Thank you so much, this is awesome. I make majolica, which is earthenware, and I use food safe glaze and stains on it. I add an extra layer of clear glaze on top of anything that would get in contact with food, just for an extra precaution.
Question: can you get as bright colors with stoneware? Thank you! Fantastic video ☺️
SUPERB video! 🕊
Great information
I love your videos!
thank you!
Thank you for the info! Excellent expansion.
Question…if your pottery is not vitrified, what can help it become vitrified? Refire?
Super informative and makes it a lot less overwhelming.
Question. I’m a noob. If you really can’t live without the crackle.. is it possible to put a clear glaze over top and fire again?
You had a lot of great response on this video. 😊. I guess you had better make more for us dummies that are slow. Ha ha. I've seen more question. You are popular. 🤗😊😉. Another words.... Please make more!
Loved this video! Do you think it is safe to use the Amaco NO. 77 Terra Cotta Stoneware clay to make plates to eat out of ?
I am so glad I found this video, I watch your video all of the time on my tv and am now finally subscribing on my computer. I took your advice and boiled a few pieces and 5 pieces remained the same weight and one piece went up by just 1. However I have another question, why is it that so many of my pieces end up firing matte on the inside and shiny onto the outside, or a blend, these pieces have all been dipped at the same time A few things come into play, 1. I fire at a community studio where someone else does the firing, 2. the glaze I used was a combination of multiple different glazes that the potter in charge of the studio mixed together but stated it was food safe. So my question is why is this happening and is it still food safe if it glazes differently in different spots on the piece ? I would love your thoughts, i am very new to pottery. Thanks.
Thank you for this excellent discussion. Can you please show us how you made your Green Dream Vase - it's so cool! Thanks!
Thing about earthenware not being "food safe" is a lot of how its used and how people prepare it.
Generally it can be pretty well sterilized just by heating it, so what bacteria or other nastiness may take up in the outer porrus layer, will get burnt out.
The big problem is long term storage and leaching. If you left something dried inside, a powder made from ground nut? a Flour? again that's probably going to be fine, but when you try to leave wet stuff, like if your making crock-pot pickles, the wet stuff can cause the most problems.
My instructor slipcasts my dishes, using Mackey's Slip (the white kind). I use Duncan Envision colored glazes, if I want one solid color. I use Duncan Concepts and Duncan EZ Stroke underglazes with Duncan Pure Brilliance clear glaze. I used Duncan Envision Clear glaze in the past, because it was easier to tell when it was dry (goes on light green, dries blue). My instructor fires everything at cone 06. Duncan Envision Glazes are food safe
Now I know where all those darts and arrows I have been seeing flying overhead the last couple of days are heading ..... straight for you Mia. Better duck and cover.
Brave of you to jump into the fray but very well done. Seldom does common sense appear in discussions of food safety in pottery.
Hey, a huge super thank you for spreading information like this. But let me ask you or did i just miss it: Did you mention anywhere the "Konformitätsregel" which says that just any piece of ceramics that gets in contact with food or drinks is supposed to be tested in a laboratory in Europe and definitely in Germany it gets inspected at markets?
I have a few plates that I bought from a thrift shop and there are this cracks in the glaze, but the ceramic seems intact. I’ve used them for years. In fact, they’re my favorite plates! I’ve never become I’ll from eating off of them. I’ve never had one break in the microwave, and the dishwasher hasn’t damaged them. The only thing I’ve noticed is that the cracks have a bit of staining that I can’t get rid of. They’re washed and dried well, so it doesn’t bother me. Thank you so much for this very helpful video!!
People have been using lead pipes for thousands of years too. I think it’s important to find new techniques, suitable for modern standard of safety, and adopt them in DIY craft. So that the thing looks old school, yet is microwave- and, more importantly, stomach-safe.
thanks for this video! What about self-made glazes for stoneware that contain titanium oxide for example? Can it be considered food safe?
Hi,
I like assuage on vitrification and your care.
I am a beginner on pottery.
I would like to know if I can do my glaze at home? Thanks
I just found your videos an hour ago and now I am binging. If I were a potter and would be aware of every component and process, yes
. And yes, humans have been eating from earthen ware for millennia but 2 things have changed. Scientific advances have discovered more about how things like lead or fungi affect human health and looking back at historical records, we can extrapolate the deleterious impacts. Further, we are dealing with a less local more global post industrial supply chain. So, earthen ware today compared to 500+ years ago, has the potential to be contaminated.
I get way too wonky. So, not a potter. Love your channel. Going to read the articles now.
Have you done yarn bowls? UT your yarn inside and feed it out through an open coil. Some have "pockets" to hold your needles or hooks (I just watched your Christmas greet q and a and saw the granny squares)
Super agreed. If you let some mold/bacteria grow on the crazed glaze for months or years that's a lot different because the bacteria has more time to get established, but if you wash your dishes pretty quickly then it seems like a non-issue. Weird to think the whole thing is tainted instantly. I liked your point about the colonialist way of thinking that can contribute to that idea, thanks for bringing that up.
Is stoneware glazed only for baking at 1100 degrees not enough vitrified and therefor not foodsave?
Thanks for your answer. Anita Muller, The Netherlands
What about pottery vases that "leak" from the bottom when full of water. Also related to heat temperature?
I use only mid fire stoneware since I mainly only make tableware. That’s just what I’m sticking to. No judgment on anyone else what they want to do.
same here!
Please advise: Though I rinsed my unglazed water pottery jar over a three-day period before I first drank from it, the water in it still tastes funny and leaves some sort of residue in my mouth. Safe or not?
Hi 👋 totally new to this but my aim is to make functional pottery, i.e. tableware and cookware. Your videos always make me smile and are incredibly helpful and straightforward, Thankyou 🙂 Would it be possible to do a video to explain how to season ceramic cookware please. I have a beautiful (purchased) pot with an unglazed base but am too freaked out to put it on my gas hob in case it destroys it 😳 poor little pot sits unused on top of a cupboard, I'm sure it's starting to have identity issues 🙃 I would like to try and make some saucepans too. Many thanks, diolch yn fawr 😃
I am so curious about that too! But honestly I have no experience with stoveware. If I learn about it I will be sure to share.
@@PotterytothePeople 🙂 Thankyou... and if I do find out, I'll let you know. Have a great day 😀
lets say you have stoneware clay and you use a food safe glaze covering the entire piece. if there is glaze covering all of it, can water still get through to the clay?
Does anyone know if you can make glazes that are not food safe, food safe by covering them in food safe glaze ?
This is video is so informative. Thank you so much! I have one question that came out of it tho :) If I can't assure vitirification of the ceramic, than it can't be defined as food sface right? To give an ilustration: I just bought an old kiln (those ones where it only shuts when the cone melts to its temperature). If I have a cone that melts at 1196ºC degrees and use it to fire stoneware clay that vitrificates at 1200ºC degrees, there is a difference of 4ºC degrees. I can't say that those ceramic works are food safe. Right? This having in mind the single fire method.
Sorry, your video was so detailed and informative, but I still have this question. TSMIA!!
While I suppose I understand your point, 4ºC is nearly meaningless. For example from an Orton cone chart from 2001, a cone 5 large cone will be bent at 1184ºC if heated at 60ºC/hour (for last 100ºC of firing) or at 1205ºC if heated at 150ºC/hour that is a 21ºC span for the same cone, and the higher number is above your 1200ºC.
Since those are stoneware temperatures I wouldn'longer
I use home dug earthenware mugs, but they are glazed. I'm thinking that the glaze soaks into the pores of the earthenware and provides a thick sealing layer, cheers
For sure, but I would still be careful with dishwasher/microwave. Likely the whole pot isnt glazes (usually bottom is left unglaze) and if there is any imperfections in your glaze, water will creep in!
@@PotterytothePeople I see where you are coming from but for the fact that both of those items are alien to us. And the bottoms are glazed and fired on stilts, but there could still be some water ingress so good thought process, cheers
Surely if actual food or drink containing surfaces are glazed there is no food issue? Microwave risk yes ....mouldy bottom of item if not glazed yes.
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I'm still a bit new to ceramics, so if someone could clarify something that'd be great. My impression was that earthenware was things fired around Cone 6 and below, and stoneware was high fire, is there a different distinction? Does that mean anything fired 6 and below is considered (by some) to be not food safe?
I was learning at a studio that only used high fire clay and I'm moving and looking for a new studio, but a lot of them only do firings up to Cone 6, should I make sure to only go to a studio that does high firing?
Thanks for asking this! I'm curious as well. I'm learning and both places where I'm taking a class or practicing use low fire clay because of how they fire. I want to make food safe pieces that are also microwave safe (a mug for my mom, for example, but she likes to reheat in the microwave). Can I do that with low-fire clay as long as it's stoneware? Hopefully someone will chime in (or I can just ask my instructor lol)
Does this test for lead in the glaze? Waterproof does not mean food safe.
This was so helpful! I’ve been making pottery for a couple years but recently got a wheel and kiln on discount. I’m hoping to make and sell my work but I have a few questions. First of all the clay I have stays porous after fired because it’s low fire. (My kiln barely goes up to 1000 degrees C) I thought that because the glaze is food safe and waterproof it wouldn’t matter but when fired it crazes. Are my pieces still food safe/sellable? What should I do to prevent this problem without having to buy a new kiln?
Thank you for making this video! So fucking educative (:
I understand you have to boil your pieces for FIVE HOURS for that test to be accurate. If that’s stoneware you boiled and thought you got 100% vitrification, I’d research and retest. Each clay body will also have the absorption information from the manufacturer. Thanks for your videos. I enjoy them.
oh boy! A 5 hour boil is a little intense haha but I am planning to retest by soaking it for maybe a week or so!
Boiling to get air out of the clay, and cooling under water to fill the pores with water, is what I’ve read.
Digital fire SHAB test mentions boiling 5 hr, then soaking 19 hr to get quantitative data that can be compared with literature. Almost certainly shorter times will work, but these procedures seem designed to be certain no change will happen in longer times.
If you have no options other than using porous pots for food, here is the way to sterilize it.
1:28 of CARA MENGATASI KENDI BAU APEK DAN JAMURAN video by Mbok Jar channel.
But, notice that it is the traditional way not a modern standart procedure.
I harvest clay from my front yard. But I plan to only make decorative pieces - especially if I sell any. Too much risk with selling earthenware table ware, at least for me 😬
Vitrification of the clay and glazing are not the same thing though they both reduce porosity.
Haha love the thumbnail
I was in a spicy mood today 😆
I thought if you put a food safe clear glaze over a non-food safe glaze that you are all set because the top layer is food safe? Is that not true?
the problem with that is crazing or chips can happen over time. and then the non-food safe glaze is exposed! 😬
To measure porosity you need to use unglazed ceramic. Otherwise the test doesn't make any sense. Also you need to let it sit in water for a day or so. 10 minutes won't do. Also there are still pores in the ceramic. There's a difference in pore type. If the pores are not connected it won't absorb water. There's a bit of a hype about the whole food safe topic. It seems to be a mystery to most people very much like being frost safe. Those are difficult topics. You often hear wrong or only half true claims online. I wouldn't worry about crazing in the glaze. Especially for things like tea bowls or coffee mugs. People who scream the loudest about pots not being food safe usually have very little actual experience. No need to get discouraged.
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I use porcelain
I notice you didn't mention "oven safe." Is that a different topic?
True! To be honest I haven't explored that topic myself, and it's something I don't get asked a lot about. But perhaps it's worth an exploration!
Oven safe is another topic, the pottery has to be able to handle temperature shock. If not, it can break when you take it out of the oven and put it on the table. There are clays that can handle that change well, it usually is mentioned on the packaging.
Technically metal is fine in the microwave as long as it doesn't have sharp edges or get close to the metal walls. Which are metal. In your microwave. Just don't touch it till it cools down
Colonial way of thinking or scientific way of thinking ?
Personally, I like lead mugs. It's heavier and won't tip over. I drink my coffee out of mine every day.
I eat from unintentionally crazed bowls (they’re cheaper) all the time but that’s just me
As a person struggling with environmental health issues I don't need the added issue of lead poisonong.
You don't sell what is considered non-food safe ware as food safe to protect you, your home, and business from un-scrupulous blood sucking lawyers.
There are no "colonialist undertones" in saying you shouldn't use porous ceramics for food. It's literally just that food safety standards have increased and those things no longer meet the standards. "Colonialist undertones" gives away your very American centric view of thing. People all over the world make these things and the standards are the same in Europe too. I can't speak for anywhere else since I don't know, but I would speculate that most of Asia and the Middle East also has the same standards now.
Does that mean you can't use them? No. Same as people use untreated wooden bowls and spoons. Just be aware that over time they might "go off"
I would like to say, that I don't share your opinion about hygiene and colonialism. Great video non the less. I just wanted to get this point of no real value on the internet of my chest. Thanks :)
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