Hello, I'm Professor trim burning and today we're talking about the art of creating and TIG teaching wheel prone ceramics, but before we move on to the wheel and the forming processes, first we need to cover some basic terminology and crepe clay properties. First we should start with is what is clay. Essentially the purest theoretical sense of the word clay is alumina, two parts silica, two parts h2o. And what that means to us what that means to you is this aluminum silicon molecules come together to create these clay platelets that float along this layer of water. This layer water makes this clay very fluid, very plastic very workable. This is where the majority of our forming techniques will take place.

Starting at the beginning of our process here, we're going to Take a look at slip which is the most liquid form of the clay that we will be using. There are a number of different slips that we use casting slip which is used in mold work which we will not be covering. In this book the sections were focusing more on wheel work, we will be covering decorating slip, which is a very smooth porcelain like clay body that has colorants oxides added to it. You can do a number of different techniques that we'll cover during the decorating chapter of the book. Also we will be covering bonding slip which is essentially your clay body broken down into water roughly the consistency of a yogurt and this is used in when connecting joints connecting parts or attaching handles. It is not slip you need to still work your handle your joints together but it helps to equal out the moisture content the moisture differential within there.

Okay, so that is our slips Next, we move to our wet or plastic state of the clay. I have two different clay bodies here we'll be looking at differently off and on throughout the, the sections. One being a B mix, which is not a portion of that porcelain, like a very smooth, very tight clay body very smooth is it doesn't have large particles but it does have a higher shrinkage ratio which makes it a little more chancy to warpage compared to our stoneware body here, which we make right here in our facilities. Now this is a standard stoneware body and as you start off with your own forming processes, this is what I recommend that you use a nice well rounded stone where it has some grit to it. So it's going to stand up is going to be workable and it's going to breathe a little bit more so you're going to be less up to crack edge, shrinkage issues, things like that.

So we have our slip, we have our wet plastic clay. So right now we're going through the stages of the clay. The next stage of the clay will be Be our leather hearts state of the clay often compared to working with a slice of cheddar cheese. Now this is when the second majority of your forming is going to take place when you're stacking sections when you're trimming your vessels when you're attaching handles that will be done at the leather hard state. The clay has lost about 30 to 40% of its moisture from this date to this date, but it still has enough moisture in it that you can still attach appendages and things like that. Given the proper precautions of slipping scoring which we will cover later.

Beyond this point, you know let's step back Take a look at this other heart state again. At this wet state, this is the most plastic this clay will ever be and this is again when the majority of reforming is going to take place. It's one of the magic times that click is so it is so easily textured, shaved manipulated, you can take this stamp it and if you were to take this and fire to the proper term insurers can be around for thousands of years. The most plastic safe the most workable state, the leather hard state is the strongest state this clay will ever be in. Because of these clay platelets. Right now they have lots of water floating around at the plastic state, they still have, they've lost some of that water, but they're still floating around, they're still pretty workable.

When we reach the leather hard state, they've lost even more moisture, and they've begun to shrink and tighten up even more, but they're still bonded at a molecular level with that h2o. Keep in mind that we are shrinking through all these stages and will continue to shrink all the way down the chain here. Once we move beyond this leather hard state, we move into what is called the bone dry state. And at this date, this is when all that water that can naturally evaporate out of the material out of the where has so these clay platelets instead of being medically bonded with that water now are essentially just sitting on top of each other. Which means this is the most fragile state this clay will ever be in. It'll simply fall apart in your hands.

If mishandled so be very careful with your wares at this date I see vessels broken all the time from Miss handling at this date picking the piece up by the rim, bumping it on the shelf, picking up a piece by the handle. Okay, so do Be very careful both hands be very gentle again, the let the heart state is the strongest state. Bone dry is the most fragile state the most fragile state the clay will ever be. And now at this point, once you reach this bone dry state, you are ready to fire Where's fired and that is first bisque firing, which is a very low firing process. And what that low firing process does is generally fire around to count oh six, which about 1860. We'll talk about here in one second, but what it does is it reaches up to this point where the wares go under a process called centering and that's silica within the clay body begins to melt and fuse those clay platelets together.

Just barely fuses them together so they're still very porous and absorbent so they can absorb the glaze material. And then after that state you can take it and fire to a mature temperature. So let's talk about those cones. Right here is an example of our cones and what a cone is. It is basically a clay and glaze material that is designed to melt as diffic temperature. So we look inside the kiln and we see these cones melting, we've know we've reached a mature temperature.

Here is a cone pack, which is a set of cones that are designed to manage different temperatures lower to hire, so we know that cone oh six has melted, we've reached our bisque temperature. Now there is a very clear distinction between this and this. Everything on this side of the table is clay. Clay can always be rehydrated, reused, recycle everything on this side of the table once it's gone through that sintering process or that initial initial bisque firing is ceramics. There's again a very clear distinction between clay and ceramics. ceramics cannot be rehydrated recycled reuse, because it has gone through that process of sintering.

I mentioned we are taking a look at a couple different clay bodies. As we move through these steps, the clay is shrinking, shrinking, shrinking, shrinking, shrinking through all these processes. I have a couple different examples of some clay bodies here. The higher the temperature, the more the clay is going to shrink, but also the different clay buyers are going to shrink, the more clay body shrinks, that is the danger zone for the most part, that's when things are most likely to warp and crack. So certain clay bodies have a higher shrinkage rate like porcelain or be mixed compared to a stone where Alright, so we've gone through this initial bisque firing. Now we're ready to move on to our glaze firing.

Now again, depending on the temperature you're firing to, the more the clay is going to show If you're working with more with a low file or say your rack to, the clay body may only shrink, you know, around 10%. If you're firing to a mature content, which is around 23 5023 at the clay is going to shrink anywhere from 10 to 15%, depending on the clay body you're using. And that is a significant amount that is worth taking note, especially if you're making a piece for a specific purpose. You want a nice big coffee cup, you throw that nice big coffee cup to the size you want it but after it goes through all these steps, and all this shrinking processes, you end up with a cappuccino cup. Okay, because 10% is more than what you might think it is. Here's an example of a cone 10 cone pack.

Here is the pre fired compact. What we do here what a majority of ceramic artists I've hired to continue to do a cone 10 reduction. So that's why the cone pack is so detailed. It tells me what temperature I am and what point i wants to set the comb or the count into reduction. You can see how the clay body has changed and matured. It is now a vitrified hard state.

It has pulled some of the metals out of the clay and it kind of has this nice speckled stone where work what this vitrified word what that means is when we're working with this cone 10 clay body will fire to a mature temperature which means cone chin. Because we're going to contain body when it's fired to that mature temperature. the wearer continues to go through that process of centering, but now instead that silica just barely melting and bonding together, it begins to fully fuse and melt together, fill in all those little pores holes and create a nice vitreous or watertight body. Then with the layer glaze on top, which glaze is essentially glass. It creates a nice seal over the surface gives it a beautiful decorative quality and makes it food safe. Now it is important to be aware of the clay body that you're using and the temperature range that you are able to work with Then, there is such a magnitude of clay bodies out there from low to high to very plastic to very tight, smooth high Grog, low Grog, you name it.

There's tons of them out there. I am going through these sections with the assumption that you're working with a cone tin stoneware clay body. So some of the suggestions that I make about weights and shrinkage ratio and it may work if you do this is working on this assumption. And again, it is very important to know the clay body that you're working with, because if you are going to be firing your pieces to content, but you go to Michael's or Hobby Lobby and purchase some of their clay which is most likely a low fire clay body, your piece can come out of the kiln looking something like this. This was once a thrown vessel, but the clay itself literally melted inside of the count. And if this happens, it is a very bad day.

Because this pot is going to melt it's going to stick to the shell stick to the pots if it drips off the shelf it could damage your Killing Floor. cause a lot of damage. So be aware of the clay body that you are using. Okay, now before we go on let's talk about a couple basic clay principles, some very simple do's and don'ts. First, let's do a little test to check out clay body and see how smooth how plastic it is by rolling out a small coil roughly about a quarter inch and wrapping it around your finger. If that clay does not crack that tells you have a nice plastic clay body.

If a clay body is more likely to crack or tear on you during this process, then that clay is referred to as being short. It is less plastic. Now this clay body here is a higher grog content so it's probably a little less short. You'll see some hairline cracks in there but it's still fairly tight against a nice all around workable clay body. All right. Let's talk do's and don'ts when we're working, throwing on the wheel, rule of thumb nothing thicker than your thumb.

Try to keep your floors in a wall about a consistent quarter inch thickness. This will give you even drying and a quarter inches all the thickness that you need if your piece is beyond that quarter inch thickness and let's say your your walls your floor moves more into this inch thickness. Well what happens here is the moisture cannot fully escape the core of the clay. So even though the pace the piece may look and may feel bone dry, there is still moisture trapped within inside the core of this clay. And when you fire in that this kiln, that moisture is going to turn to steam and cause the piece most likely generally speaking the bottom of the piece to explode and your piece is going to come out looking something like this. You can clearly see how thick this wire was.

Okay, that's a bad day right there, right? So keep your thickness, nothing thicker than your thumb. Generally speaking about the thickness of your pinky or quarter inch Okay. Now, talking about that thickness keep in mind the clay is constantly shrinking as this losing moisture is shrinking, shrinking, shrinking, shrinking through all these stages. So again this is why proper thickness is so important because if your walls move from say this, you know half an inch to these very thin spots or something like this, these thin spots are going to dry quicker and constrict quicker than these thick parts and that can cause stress cracks in between here. So, if you find you have a very thin spot in your wall or the floor is very thin, it's very common to see a nice round crack around the base of a piece from over trimming, which again we'll talk about that when we move on to trimming but just rule of thumb keep your walls about a quarter inch thickness.

The last thing we need to talk about is air bubbles and air pockets. What is an air bubble? Well if you have a small little air pocket on the side of your piece Something like this and you're throwing your vessel it's gonna appear to be similar to like a little blizzard. If you burnt your hand, a little blister, not a big deal. Take your pin tool, pop some holes in it, continue throwing in is going to work that moisture out. But you can never have a fully enclosed form.

Okay, a small air bubble, okay, that might just damage yours. But if you have a larger air pocket, say you're throwing a double walled vessel or a closed container, something along those lines. Well, if we were to take this little pinch pot right here, fold that over, pinch it shut, make this nice little longtime here. Well, this is what we what we would refer to as a clay bomb. This will explode during the firing because the clay again is going to continue to shrink during the firing. We have an enclosed pocket of air is going to start to collect some of that moisture escaping at that molecular level.

The clay is shrinking, and at some point that clay is going to hit that critical mass and boom bigger piece like this, it most likely is not just going to take out your piece but it's also going to take out surrounding pieces and it's gonna make a mess of the kill. So those are three big things to watch out for proper thickness, air bubbles, and moisture content, make sure your pieces are dry before you fire them. Okay, the next thing we should talk about is take a look at our tools.