Episode 100!

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Hello, my name is Kathy King and welcome to the For Flux Sake podcast. I'm coming to you from the Harvard Ceramics Program in our fair city, Alston, Massachusetts. I'm here with Rose and Matt Katz of the world-famous Ceramic Materials Workshop and they are ready to answer your burning questions about clay and glaze. Well, howdy, Matt and Rose. Hey, Kathy. Hello, Kathy. You know what I always say about you two?

Oh, no, I don't know them, officer. I'm innocent. What did I do? I say you two don't look a day over 99. I'm feeling, I'm feeling. hundred though are you we're talking episodes people this is our i know this is our hundredth episode how awesome is that 100 episodes of disappointment. No, come on. Just when you talk.

yeah rose and i are good rose exactly we're good yeah we're lifting lifting the people lifting the people up i've been disappointing people for decades i'm used to that to bring down rose's elevated status because otherwise she'd just be in the clouds that's true i'm full of helium hey and i'm full of something oh my goodness i i mean i can't

I can't believe it. It has gone so fast. It's crazy. All of our little Zoom boxes here together with producer Ben. I wish we were together more in person, which is a goal for the next bunch of hundred episodes. But let's get all nostalgic for a second. Tell me something you've learned through doing fabulous podcasting. I mean, I learned how to calm the nerves beforehand and just let it go. I used to get so nervous. Absolutely. Me too. Mm-hmm. Mm-hmm.

Not Matt. No, not Matt. No, I can always just talk. That part doesn't bother me. But I have learned how much I don't know about running a public studio. Oh, thank you. I'll take that. And I will remind you and continue to remind you. Put him in his place. I mean, I think walking. into this i i really thought i had an idea of what kind of questions that were going to be asked and um i think

The thing I learned the most was how much more varied the questions are. You know, it's people are coming at it from so many different, you know, directions in terms of like digging up their own clay. and putting that in the kiln. And what can I burn in my kiln and still survive? And I mean, there's some really like out of the box thinking. And it makes me think about because I am old, you know, back in the day, like when we were.

in school and learning we had it was in my generation it was before the interwebs right and so we had the same textbooks the same magazines we were all sourcing the same information So we were kind of moving together as a pact. And now it seems, you know, people have access to so much more information and so many more ways to get in trouble, apparently. So much more bad information, like this show. No.

But it does make me think like how helpful it is, you know, that you all started Ceramic Materials Workshop. You know, it's made such a big difference in our studio to get people like in the same conversation and not, you know, dispelling. like crazy ass facts, but like having some sort of groundwork in which to work from. The democratization of information, to get really technical and studious about it, like is a huge deal with the internet because, yeah, I mean, like we're...

Rose and I grew up with the internet like it existed when we went to college. I barely used it in college. Yeah, it was mostly just email. Yeah, dial up. yeah but like you meet people from other schools but you'd meet like students from other schools and they'd kind of know the same information and they're sort of the same educational philosophy because a lot of the teachers were coming from the same school

and that kind of thing. And it definitely has evolved into different ways of making... people being open to different types of process and really looking creatively at new ways of decorating and new materials that you can use like non-traditional ceramic materials or different firings or different. sort of just ground up level process which is kind of amazing that that type of liberation um is is both freeing

But then from our end, getting a lot of people that end up behind a rock that they don't know how to get themselves out of. And so for us, it's we really like to be there as sort of a clearinghouse for good information because there's still a lot of... That's where we come in. And it makes me feel it.

Right. It makes me feel good if people feel comfortable in calling in and not second guessing whether it's a dumb question or a smart question, because I think like we've all learned, it's even the most basic question. is information to go through there's you know stuff to figure out and to share with the audience and um i love that yeah and and you know i mean kathy both you and i are inherently teachers not that rose isn't a teacher but rose all that much teaches you

She's the one who talks the least but is the smartest of all of us. And probably from the lack of talking. Exactly. That's just my upbringing. But that there definitely is. There's a complete other brain fart in what I was going to say. Oh, man. I have learned on this show in 100 episodes how to make y'all sound smarter. Oh! Yes. Ben, how do you put out a show of 40 minutes of silence every week?

It's tough. So, Ben, producer Ben, do you do you speed us up sometimes to get to the point? And I'm not pointing anybody out out of the group. I do. Let's just say that the episode the listener hears is sweetened. It's shortened and sweetened. Oh, nice. And they don't see our hand gestures, right? Or my eye rolls. I see it.

I see it and I try to wrap it up. Oh, I know you see it. I know you see it. Well, awesome, gang. And here's to a hundred more, huh? Absolutely. And as we keep going, I will say to everybody out there, keep the questions coming. Questions are always welcome. And you know what Kathy was saying a second ago of. there is you know as a teacher really what i do believe is that there is no such thing as a stupid question it's just information that you don't have yet and you shouldn't feel ashamed

for not knowing something. So yes, the questions are always, always welcome. Although a little bit of a finger wag. I will guilt the audience a little bit. Stop sending us questions on Instagram for the show. It is not going to get answered. Like if you want a question on the show, submit it to the show, not Instagram, not going to happen. You want, ideally you want to send us a voice memo.

of your question and let us know where you are from. I love that part when I get to read where you're from and you want to send or email that voice memo to for flux sake podcast. at gmail.com. Just easy peasy. Lemon squeezy. That's right. That's right. And while we're at it, let's do a group activity. Let's ask everybody out there, if you would, on whatever platform you're listening to us on, go into the comments section and give... us a favorite memory or

argument or stupid joke, or, you know, maybe share something that, you know, helped you specifically, because we're in a bit of a bubble. So any opportunity that we get to hear from you. outside of your fabulous questions is so great. Feel free to emphasize how dumb we are. Matt. Matt, in particular, Matt. All right, Lord Celsius, let's start. Let's get into it here. We've got questions to answer.

So for our special 100th episode, our first question comes from Asuka from Philadelphia, and they are asking about glazing a piece before firing it. Hi, this is Aska from Philadelphia. I know from listening to previous episodes of the podcast that new glazes need to age. And so I have started waiting three days after mixing a given glaze before testing it out. And my question is, do I need to wait any length of time after dipping my tile before putting it in the kiln?

And I guess that question extends into larger pots too, just generally speaking. After dipping a pot in a bucket of glaze, do I need to wait before firing it? Okay, thanks so much. Oh my gosh, you guys. You guys. I'm crying. Why? I'm crying. Why? Because we've had an influence. She's learned to age your glazes. Oh, good. Okay. A hundred episodes. People are hearing it. And that makes me feel soft inside. Give a recap. Give a recap. Why do we do that?

Right. So aging our glazes. And I will say as a person that like makes test tiles for a living, that's what we do all day long. The thing everybody does wrong with their glazes is that you mix up the batch and then you just start. applying and that is a huge huge problem for long-term consistency of your glaze because

Over time, especially the first three days, there will be material that will dissolve from our glazes, generally things like sodium. And sodium will act as a dispersant in our raw glaze and it will make it change how it flows. over those first couple of days and so the big problem is if you mix it up on the first day and you're like this glaze is super thick and then you add a ton of water to thin it down when you come back in three days now it's way over watered and it'll never be the same

So realistically, we need to wait those three days and let the glaze age before we start to get serious about learning how to apply with it, because it will change over time. It might not be much, but it will be some change over those three days. For those of you in community studios, what we started doing is we laminated some half sheets of paper where we say we have a line after mixed and then a line to put out. And so we can.

Our glaze mixers can write the date that the glaze was mixed. And then to make sure nobody's putting it out on the floor too early, we wait three days so that we can then check the water again and make sure that it's tip top before we go have three. 350 people use it. And it will make everyone's life better. It sounds like a dumb step. I'm sure it's infuriating to have it sitting there and everybody wants the new bucket of glaze.

But especially, and again, talking about like the things that we've learned about public studios of like, you have to force the issue because in a public studio. no offense to the people in the public studio, but like you guys are kind of the working experience, lowest common denominator. And it's really easy to screw stuff up when you don't know the experience level of all the different people coming in to use that glaze. So you really need to make sure.

sure everything is tip top. I know Kathy just made a cross face that I called the lowest common denominator. Yeah, we could have phrase that but go ahead y'all suck man like what what what's up here we go here we go rose rose rose well well matt's very good at this he's very good It is... evading the actual question is she need to wait to fire her piece oh yeah we were getting you know yeah but you know 10 minutes later come on we only have one

Time's ticking here. Good point. Good point. Was there a question? Was there a question? Yes. Well, I mean, I would, you know, again, I'm the one here who is the most not a potter. um so i you know yes you should answer no but i was gonna ask i was gonna ask kathy or even ben you guys are making pots like what's what's your approach with with as far as glazing and drying do you wait do you throw it straight in the kiln what do you guys do

Ben? So I wait until it's not cool to the touch anymore so that the... moisture from the glaze has gone through the bisque and then out into the atmosphere, which depending on how hot you're bisking, that could be different. So sometimes it's a couple hours. Sometimes I was bisking really hot for a while and it was like a day. And I stopped doing that because that took way too long.

Yeah. And I tend in my own studio because I don't have a ton of space. I glaze and then I'm pretty much loading as I'm doing it. So, you know, once I've got the whole kiln loaded, if I'm in a super rush, I might. put it on i don't know like 80 degrees or something for an hour or two and just like make sure everybody's dry but yeah same thing not until it's not cool to the touch yeah yeah and that that's basically the the correct answer um how long you have to wait

Great. Ben, we did it. All those decades of being potters and working artists. We basically got it right. You finally got it right. A hundred episodes. Y'all learned something. No, no, no. But like, I have heard a lot of potters that'll get like real paranoid about letting their glaze application dry overnight, or they'll put a huge drying cycle on their glaze firing.

And like for bisque, totally different conversation with bisque. Bisque ware is wet. And so you definitely need to make sure that you've evaporated 100% of the water. Oh, my gosh. In production, it was like if it was bisque, it went right into the kiln. It was like we're not. waiting for that to dry go go go but if it was once fired that's a different story i had to dry and then go in the kiln

Well, that's a perfect segue because our next question from Rachel in New Orleans is about single firing. Hi, Kathy, Rose, and Matt. This is Rachel from New Orleans, Louisiana. Thank you for your podcast. I've learned so, so much, and I thoroughly enjoy your conversations and personalities. It's wonderful. Thank you so much for what y'all do. My question is about raw glazing or single firing, and I can almost hear your sighs of disgust.

I'm a sculptor. I'm not a potter. And I know a lot about clay bodies. For years I've worked with clay, but I'm new to glazing. And I'm looking for ways to make this whole process a lot more improvisational. And I would love to know what you think about the prospect of that. And I know Rose is going to say test, test, test. And I am about to launch into a bunch of tests, but I just want to know if there's some big pitfalls.

that i need to look out for and if there are specific glazes that work well for this or that do not or clay bodies for that matter that work well with this and i would like to know what you all think thank you so much No sounds of disgust. I mean, I've never had the guts to do it, but I know, you know, amazing artists such as Susie Lindsay in North Carolina is a single fire. She does soda and salt.

Um, but I don't know many people who do. There is no reason why you don't have to, um, to, to bisque. You do not have to bisque. But there are huge caveats. But even going to Rose of, you know, the crazy thing is, is industrially bisking is not as common as you would think. That that's like a wasted step. They're like, why would you do that? That's like wasted energy. It's wasted energy, but it's also wasted time in the kiln. Like, you know, like in the tile factories.

putting tile which is a massive amount of square footage through a kiln twice like you can't be serious like they don't have the time for that Well, yeah, it's production time. It's square footage to get out the door. It's scheduling nightmare because you have to run everything through twice.

And Fiesta Ware, we know we visited there not too long ago, which is the biggest anywhere company in America. They once fire. It's all once fire. Because if you've got to get pots out the door, those double cycle and to have the pot sit around and all that. waste of time, huge waste of time. Um, so no, like you don't have to bisque, but, but, but so, okay, Kathy pop quiz. What is the number one reason why we bisque?

Well, I tell people we partially fire these pieces so that they're not as easy to break and that they're yet still absorbent so that we can dunk them into the bucket and they'll take on. An amount of glaze according to the thickness of the bucket. Right. It is true. Bistware is tougher than greenware. That is true. But at the same time, like, let's be honest, like my mother.

you know who i won't say her age but you know she's not she's not the youngest person she could totally break this square with her bare hands um like it's it's not that much stronger to to to bisque something versus green There are application problems with getting something that is still could be recycled, could be reclaimed and getting that wet. That's not great. But, you know, application times are so quick, you know, with the dip or the spray, it's not that big of a deal.

But there is one reason why we bisque. That is absolutely the benefit. It absolutely makes everyone's lives potentially better. And that is the prevention of explosions in the kiln. And right, so going all the way back, why does work explode in the kiln? It explodes because there's moisture in it 100% of the time.

To drive this one home, it's never because of air pockets. It is always because there is still moisture inside that clay. Moisture gets hot, it turns to steam, and then steam builds up pressure really easily, and that creates an explosion. So it's interesting to think that in her case, and I don't know what kind of sculpture she's making, like, you know, the only people I've known to do this have kind of are.

production potters, they've got thin walled pieces that there's some consistency through the way that they make pieces. So are there different considerations when you have a thicker walled sculpture? Yes, yeah. You have to be careful of your moisture. So you have to make sure that thing is completely dry before it goes anywhere near that kiln if you're once firing.

The consideration of the moisture is the same metric that we have when you're making pots. It is just you can virtually guarantee that there is a lot more moisture in that sculpture. deeper in the thickest crevices. or in those cavities you know when you you know if you make it thick and you carve it out that underside of the foot is not exposed to air so it is going to dry very slowly and will hold in moisture and that's where we really have that big threat

But if you dry it thoroughly, like thoroughly, thoroughly, there's not a threat beyond that. But you just have to make sure that you get 100% of the moisture out. So like with most BIS cycles, like at least in the way the computers program them, they'll give you a drying, they'll call it a preheat sometimes, that they'll give you an optional drying cycle. And like, yeah, use that.

depending on how thick that wear is. And basically what they do is they go up to about 100 degrees C. um which is 212 f which is the boiling temperature of water and then they'll sort of sit there some of them go a little bit hotter which makes me a little uncomfortable i'd rather sit at like 90 degrees c which is like 200 f which is under the boiling temperature of water and you're just trying to force the water out. And you can sit there for as long as you feel comfortable to get it to dry.

Like I know when I was a student and we'd take, you know, we do sculpture classes and you'd get like 20 students that are making giant clay things and they're all thick. We would at least dry overnight at a minimum. You'd candle overnight. Yeah. And that'll basically save you from it.

But that really is just to get the moisture out. And to go back to our previous question, do you have to do a drying cycle with a glaze application? No, not really. We'll be glazing until the end of the day and we'll just put... wet things in the kiln and just start a glaze cycle because that water content is so low and it's in the bisque wear and it doesn't build up pressure because everything still pours and all that

So that's not a big deal. But if you're once firing work and that work is big and thick, definitely give it some time. But what about if she's committing to... single firing she will want to adjust her water in her glazes in a different way correct yep definitely yeah i mean how When we talk about bisking in application, it comes down to the absorption rate of that clay body. So that the clay body will wick the water because our clay acts like a sponge.

Un-bissed clay will generally have absorption rates at like 10% to 12%. And when we bisque it, it goes up. So stonewares will have sort of 15 to 16% absorption and porcelains can have up to 20% absorption. So it does go up. So you may say if you're once frying, want glazes that have a lower water content because that clay's got less absorption. And so if you have a really high water content, you won't get a good enough thickness of coating.

If it's too low, but if you've got the bisque wear, the absorption is going to be much higher. So you actually want more water so that it doesn't put too thick of a coating on too quickly. But for the application, that's the, and then actually then the lower water content, you also have less water getting into unfired ware, which as we said, could recycle it.

And then the other thing is just as far as the firing, like a lot of people freak out about like the burnout cycle in once firing. But let's be clear, everything that burns out of our clay bodies is burned out by 850C. which is like cone 012, which is well before things start melting. And so as long as nothing's melted, all those glaze particles and clay particles, they're still individual particles. They haven't melted. So there's plenty of space in between them for all of the...

carbon dioxide or whatever else is escaping to just escape. It's not going to be a problem for how it's going to stand up, but you definitely have to watch out for the sensitivity and the drying. Like that, that is no joke. But if you can get past that, figure out your application. Yeah, man, once fire, there's no reason not to just know the perils. Rachel, you're on your way. Saving yourself a whole firing.

Let us know how it goes. So anyway, y'all, until we see each other again, Matt and Rose, adieu. Bye, Kathy. Au revoir, Kathy. Silly. Well, folks, that's it for this week's episode of For Flux Sake. I'd like to thank the listeners who submitted questions this week. And if you want your question answered on So join us next time. And when in your studio, remember what Rose always says. Always remember to test, test, test. This is a test of the emergency glaze system.