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The basics of glazing ceramics



it's always when you get to glaze your pots pink and looking like everyone that's really really beautiful and unique so today we're going to talk about glazing and just the very basics of how we're going to the first thing you want to think about is it actually this square and that's a new term for us this square means it's been fired in the electric kilns once which means it is no longer green we're so first let's discuss the difference between green ware and bisque ware one of the first things you'll notice is the color difference green ware even when it's really really dry bone-dry it's actually more gray than pink another thing you'll notice is the sound that it makes when you hit your fingernail or a metal tool on it so when you hit this one there's a punk punk punk almost a hollow sound like when you're hitting a pumpkin or a melon and when you hit the bisque where there's a very bright sound more like a wind chime or a bell so that's one thing you can look for if you want to get really weird you can actually lick your pot and if you lick the bisque ware pot your tongue will stick to it and it will not stick to the green worm pot but I don't recommend licking your friend's pots because you don't know where their germs have been so we look at the color we look at the sound and then worst case scenario if you're really confused you can always ask me and I will tell you if it's ready to glaze or not so now that we've decided it's actually where I want to tell you about the importance of not putting glaze on the bottom of your pot if you notice this already glazed Bowl it has a ring on the bottom like the foot ring on this bowl that has no glaze on it and the reason that is that's called a dry foot then that's also a new vocab term the reason you want to have a dry foot on the bottom of your pot is because glaze doesn't know the difference between the pot that you're glazing and the kiln shelf so if you put glaze on the bottom of your pot and then stick it on a kiln shelf what ends up happening is after it melts you get a bowl attached to a kiln shelf and that's not really useful unless you're super strong and want to lift a comb shelf every time you're slurping your cereal milk so you need to make sure there's no glaze on the bottom Potter's used to just glaze their pots and then wipe the bottom off with a sponge we have a trick that we use that makes it a lot easier and what we use is wax if it's even labeled there it is and so what we're going to do is we're going to think about all the spots that are touching the kiln shelf plus a little bit up the wall on each side as I'm waxing this I'll tell you why that's important so first I'm covering the bottom of each pot with wax and then you'll notice that this foot ring is about a quarter of an inch up on either side and what we're going to do is we're going to put wax all the way up till it reaches the bottom of the bowl and the reason we want to do that is because each glaze is a little bit different but we've talked about the fact that blaze has silica in it and silica is a glass former and when there's a lot of silica and a glaze or a lot of flux which is what makes the glaze melt the glaze actually relaxes in the kiln and I like to think of it as kind of shrugging down and it could potentially touch the kiln shelf so we need a little bit of wiggle room in case the glaze decides to run down the foot of our pot a little bit all right so now we've done the outside and that's usually the side people remember to do a lot of times what people forget is that the inside of their foot ring needs to be waxed also otherwise it's going to stick on the inside in one of the next glazing videos I'll show you how to use a banding wheel which makes this process a lot faster and a little bit less cumbersome so when we blaze this will be glazing this part of our pot the very bottom and the inside so next we need to talk about lasers when you're deciding what color place you want to use you're going to notice a lot of test tiles that are either cups like this with ridges in the middle or flat tiles that are l-shaped they also have ridges in the middle either way it's going to tell you what the glaze is going to look like after it's been fired so the reason this is important is if you look in the glaze bucket you're going to see colors like this and this glaze is tin makuu or Hamada rust is another name of it and it actually turns out this color you'll notice this side of the tile where the ridges are where it goes over the sharp edges it turns brown so this would be a really good glaze to use if you had a lot of details on your pot because you'd be able to see the details better when it goes over the surface you can also see on the flip side that when you put it on thicker it turns black so be cautious if you really like this kind of rusty black and gold color that you put it on just with one coat versus to the backs of these tiles have two dips on them now that you've picked what color you're going to do you're almost to the part where you actually get to glaze your pot but there's one more thing you have to check before you actually glaze it and that's to make sure that the glaze is the right consistency so if you look at the top of this glaze bucket what you might notice is that there's kind of a liquidy watery section on top that isn't the same as the rest of the glaze and as I stir it up the clear section of water goes away as I mix it I'm also kind of feeling around on the bottom to make sure that there are no big chunks or that one particular chemical has settled on the bottom sometimes people think that if the top of the glaze is stirred up but that's good enough but really it's not because some of the important chemicals might be at the bottom and if you don't get the right combination the glaze won't turn out the way you want it to so now that I made sure that there's no chunks and it's all the same consistency I want to think about what consistency that is and ideally you want it to be a little bit thicker than whole milk you want it to be not super chunky like oatmeal you want it to be runny enough that it goes onto your pot evenly but you don't want it to be so thin that you don't get enough glaze on there so if it's like you know thick well stir hot chocolate that's what I like to think about it is being all right when you're glazing with any of the glazes that are red colored while they're in liquid form you want to be careful about getting them on your clothes because it means that they have iron oxide in them which I said before is the same as rust so you want to make sure that if you need to wear a taper and you wear one or bring an extra change of clothes from homes that your parents aren't mad at you for getting blazed on your clothes or just be super careful when you're using these places that have a lotta iron in them so what I'm going to do to glaze this bowl all one color is I'm going to use this pair of tongs and I'm going to clamp the side and I'm going to make sure that it's firmly clamped before I let go now when I put it in the glaze I'm going to make sure it gets all the way in and I'm going to hold it under only for about a full second before I pull it out and make sure all the glaze is dumped out so you can see what that looks like so I'm going to go in 1001 and then I make sure all the glazes dumped out make sure you also dumped out the glaze that's caught in the foot ring some people forget about that and they end up splashing that on their clothes you see that the glaze is drying fairly quickly and that wax is done a really good job of keeping the glaze off the bottom next I'm going to flip it over and unclamp the pot and you'll see that there are these little marks from where the tools work so what you can do is you can put a tiny bit of little glaze on the inside if you have any cuts on your fingers any wounds from other classes if you take mr. Duvall's class you'll know what I'm talking about you'll want to make sure that you either use gloves or a paintbrush because you don't want to get the metals inside of your cut because it's not very good for you since I do not have any cuts on my finger I am confident I can smooth it all out all right if you see any of these smaller bumps on the surface those will actually melt out once it's really hot so you don't have to worry about getting it perfectly smooth you just want to make sure that it's smooth in general you can see that there's some bumps on the inside and what you can do is just take your finger and lightly sand them to make it smooth and now we can go over to the sink and get it ready for the kit to get your pot ready for the kiln you have to make sure that you have a truly dry foot which means there's no glaze on the bottom so even though that wax did an excellent job of keeping most of the glaze off you can see that there's still a few spots on there so what I'm going to do is I'm going to take a sponge and make sure that I weigh most of the water out of it then I'm going to just give it a quick little wipe to make sure that there's no glaze spot double-check that I've gotten blaze all over everywhere on my piece of pottery and now I can take it out to the kiln then it will be fired and it'll make an excellent little ice cream so some people might wonder why I only put one coat of glaze on this particular piece and that was because the glaze was just the right thickness that when I dipped it once it gave a nice even coating all over the whole glaze and I really like when the Tim McCaw glaze turns out with that rusty brown black combination if I wanted it to be solid black with this particular glaze I could dunk it a second time and that would make it darker however you want to make sure that you never put more than three layers of glaze that's not you know a hard set in stone number that's just a rule that I generally use with the glazes in our studio because sometimes if you put too much glaze on a pot it will actually run fairly heavily and this person got very lucky you can see this drip in particular went all the way down and almost touched the kiln shelf but didn't however some students haven't gotten so lucky and their pottery becomes a permanent installation of art on the shelves out in the kiln and they don't get to take it home and it's very very frustrating and then they also get to spend a lot of time grinding the shelves for me which isn't super fun so just make sure you're not putting glaze on too thick the other thing you need to make sure of in terms of caring for your glaze before it gets to the kiln is once it turns into this dry powdery chalk on the outside be very careful not to bang it against any hard edges or hit it with your fingernail because you can actually flake pieces of glaze off and then you won't have any glaze there and it won't look as nice also let's pretend you have two pots one with the glaze that's very red and another glaze that is very white make sure you wash your hands before you touch the piece of pottery that isn't the darker color glaze because it will transfer just like chalk and powder to your clothes it'll transfer to the other pieces of pottery you

27 Comments

  1. big hair

    Hi! I am refinining clay rich soil into clay at home, and do not have access to expensive electrical kilns or pure clay, and I would like to know what I can use to glaze highly impure greenware at temperatures achievable in a wood fire. If you could get back to me on this issue soon it would be highly appreciated!

    Reply
  2. keyovc Alpha-One9

    When I glaze I use to paint it on and had good results. For some reason my pots were coming back with bubbles in the glaze even though I gave it the same two to three coats. After that I just paid extra to have the glaze done at the shop. I took my pottery to different shops so I figure that some firing settings were different and that's why some pots came back all jacked up.

    Reply
  3. Jane 505

    I wasn't going to watch this as so many youtube videos are a waste of time, but this one was superb. You are an excellent teacher, Christa, and I would love to learn more from you. I love the added tips you mention. If you haven't done so already, I hope you produce a series on ceramics. Thank you!

    Reply
  4. Red Queen Official

    But where do we get this wax from? What is it called? Where do I get the food-safe glaze at? What paint do I paint the bowl with and how do I glaze it? Does the bowl go in the oven after glaze is applied? Me and my friend are trying to make a custom water dish-pool for our pet snakes’ terrariums but I absolutely can’t find any proper information on how to make a dish from scratch.

    Reply
  5. chathuri masakorala

    I actually love pottery but I really don’t know how to glaze and what are the chemicals want make the glaze liquid.. can u tell me ma’am how to make this brown color liquid,, and the names of chemical

    Reply

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