My Advice on How to Glaze Pottery

Glazing can make or break a pot, and learning how to do it well is almost just as important as throwing and trimming the form itself. I've got a pretty specific way of glazing my pots, but I think over the years I've gathered enough tips and tricks that should be useful no matter how you apply your glazes. And thus, in this video, that's precisely what I want to talk about. Specifically, how I glaze pots and how I tidy up their surfaces to achieve neat and even layers, so that I spend less time tidying the glazed surface up before they can be packed into the with the glazes I use that have to be applied in a really even manner. It's not necessarily the most creative process. So, anything that makes it more efficient and streamlines the process is a good thing in my eye, and apologies for that jump scare. I should quickly preface this video with two things. The first is that this is just one out of dozens of ways of glazing pots. I choose to dip pots, as it gives me the most uniform surfaces, but it does require having large containers of glaze like this. At the same time, you can brush glaze, pour glaze, spray glaze. Really, any way you can think of applying it can probably be done, but different potters tend to stick to certain techniques that work for them. Secondly, the glaze itself is simply put a whole bunch of different raw materials that are very thoroughly mixed in water. For instance, in this bucket is feldspar, nepheline cyanide, synthetic bone ash, talc, whiting, and some red iron oxide, in varying percentages, all mixed into water. And when the absorbent bisqueware is dipped into the glaze, the water itself is absorbed into the body. But those raw materials that make up the glaze, as their particles are too large, aren't, and instead they adhere to the outside surface. The longer the pot is dipped, the thicker the layer. Equally, if the walls themselves are thicker or thinner, they absorb more or less water, which therefore means they take on either a thicker or thinner layer of glaze. This means that it is possible to oversaturate the pot if it's submerged for too long. This normally results in the glaze itself taking a very long time to dry out, and then cracking and flaking off as it does. You can also glaze pots too thinly. It'll dry quickly, but it probably won't give you your desired results. So, let's get started with mugs. On the right are biscuit-fired pots, and on the left is a freshly glazed piece. It's very damp at this moment, as the bisqueware has absorbed a lot of moisture, as at the moment the body isn't fully vitrified. Yet, with a fully fired piece, like the example on the left, the clay body here is fully vitrified, meaning that the stoneware can no longer absorb any liquid. The before and after is always rather stark, both in terms of colour, gloss, and size, as it's during the final firing that the clay shrinks the most. And before we get into it, yes, I've waxed the bottoms of all of these. This way, glaze can't adhere to the bases of them. I've fired these mugs to 950 degrees Celsius, and you can see in places that the clay has been left a bit rough, which, in this instance, as a thick glaze is going to be covering them, I don't mind too much, as they'll be completely hidden once glazed and reduction fired. Now, to glaze my pots, I use these, a pair of tongs. I grip the pot between them and squeeze relatively firmly. In fact, you can use quite a lot of pressure, provided the walls are thick enough, but never squeeze too hard, as these can pierce the walls of the pot. Now, at the start, using tongs can feel really awkward, but I promise, just like anything else, with practice, glazing pots using these will begin to feel more natural, once the tongs become an extension of your hands. In order to glaze pots consistently, I find it helps to hold the tongs in the same way, and in the same orientation, in terms of where they grip, on the cup, every time. For instance, with any of my mugs, they're held slightly to the right of the handle, with the horizontal prongs gripping it from the inside. I'm also using a relatively loose grip, as if I'm glazing for, say, a couple of hours. The last thing I want to do is be squeezing as hard as I can that entire time. I then take the pot, gripping it just enough, and it's plunged into the glaze. I give it a quick rotation, but then I hold it steady for about five or six seconds, before removing it, letting the excess drain out, and then I flip it back the right way up, and gently shake the cup as I rotate it from side to side. This helps the glaze to settle in an even layer all over the pot, and it also causes the excess to be pulled towards the base, where it can gather in a band around the outside, the excess dripping off as I shake it. Glaze quickly dries, and once settled, I take it over to the workbench, and rub the excess off on the wood. By the way, before doing this, I've vigorously cleaned the tabletop. This way, the glaze that comes off can be recycled and reused instead of wasted. The cup is then placed on a wear board, and using two hands, I gently remove the tongs. The reason I'm making this video is I feel that often I skip past the glazing quite quickly, when in fact it is such an important part of the process. It's also a step that a lot of care and attention is put into. For instance, when the pots are taken out of the glaze and they're moved around, I'm very attentive and I'm watching the surface constantly, and I shake it proactively to prevent thick spots from forming. Instead, this rocking motion forces them towards the base of the cup, where they can form into a more uniform, thick band. What I'm trying to say is that this is not a passive process. As the glaze dries quickly on the surface, sometimes you'll get these uneven spots, and it's these that I'm ultimately trying to avoid when I shake it. But, depending on the types of glaze you use, and how thick the walls of your pots are, you'll find that they may appear more regularly, or you'll end up with cleaner surfaces like this. This is perfect, by the way, as there are no major lumps or bumps. Despite the feet being waxed, sometimes when you're using thick glazes, they can still cling to the bottom, but this is why I use the tabletop to wipe away most of it at this stage. You can use something like a flat piece of sponge, or a small, soaked piece of carpet, but I prefer to do a majority of the tidying up the following day, after the glazes have fully dried out. You can see that there are some obvious marks left from where the tongs were. Sometimes they're better, and other times they're worse. And I also don't get too hung up on them at this moment, as when the pot and glaze are still damp, it's actually relatively easy to ruin the surface if you touch it too much. You'll find that these marks get worse, as the tongs themselves have glaze build up on them. So if I see small clumps like this, I tend to remove them, as they'll simply get progressively larger the more you dip, resulting in larger marks being left by the tongs. I twist the pot around once after it's submerged, my thinking behind this being that it lets the glaze settle on the entire surface perhaps more evenly, and allows it to get into any nooks and crannies, such as in the sharp gap at the base of the handle, and into the corners on the interior surface. Thereafter, I hold it steady for about four or five seconds, so that the clay body can evenly absorb glaze all the way around. If you've submerged the pot and are constantly whisking it around, the glaze can sort of brush against itself, moving it across the surface of the cup, and thus potentially creating quite uneven layers on the vessel. One of the best tips I have for keeping things clean and tidy as you glaze, is placing all of your tools on the lid of the glaze bucket. This way, the glaze that inevitably comes off them is contained, and it makes it easier to scrape this stuff off and recycle it later. The tongs, the brush, the ladle, and the jug are always kept on this, and are never placed on the wooden worktop. With that being said, I do obviously let some glaze get on the tabletop, and before beginning this glazing session, I wiped it clean thoroughly this way. After finishing with this particular glaze, I can scrape this white velspathic glaze up, and it's placed into this basin of waste glaze, and eventually I'll sieve what's in here back into the larger bucket of glaze the pots were dipped into initially. Over the years, this has allowed me to recycle and reuse a ton of glaze, kilos of the stuff, which would have otherwise simply been sponged away, rinsed off in the sink, and caught in the clay trap beneath it. Also, just to keep the glaze dust down, I'm constantly sponging down the surfaces throughout the day, and I mop the floor around me regularly, so I'm not kicking around the dried up glaze. That's these 10 pieces coated, and really, this is the quick part of glazing, as I still need to tidy them up. The thing is, in this state, the glaze is still quite damp, and if I try to rub over the tongue marks, for instance, they don't really fill up properly. The bottoms, of course, also have to be cleaned, and all of this is a process that's simply made easier if I wait a day or two until the pots and the glaze have fully dried out. This is because, as this glaze dries, it becomes more powdery and fragile and soft, and it can be ground away and moved easily with a fingertip. This makes fettling clean the surfaces and the bottom easier, yet at the same time, it means it's more fragile, so the pots have to be handled with extreme care. It's also worth knowing that not every glaze dries in the same way. For instance, if they contain more clay, they can dry into a relatively hard layer, yet this specific recipe only contains about 5% china clay, and thus it dries into that powdery layer I described earlier. The truth is, depending on the recipes you're using, your approach on how you glaze these, hold them with tongs and tidy them up, might have to be different, and you can't rely on the technique I use to work for every type of glaze. It's also interesting how different materials mixed into the glaze can have an impact on how it settles onto the pots. For instance, with just 1% red iron oxide added to the white glaze you saw earlier, which will cause the glaze to turn green once fired, it also helps it settle into a much neater layer at this stage, the glaze settling into a flatter surface with considerably less drips and bumps. This is because it acts a bit like a flocculent, making it just partially gel-like, which helps it settle into a neater layer. Sometimes, if I release the tongs poorly, it can leave a scratched groove in the surface, and when this happens, I do just dab a bit of extra glaze into it. It's now the following day, and this white glaze has dried out. This means the pots are now ready for the second step in the glazing process. Both the glaze on the outside and the clay body within have dried out, and in doing so, the surfaces lighten and become powdery. Now, before I get started, the first thing I do is wipe clean a new wear board. This way, once the messy pots have been tidied up, I can place them onto a surface that's perfectly clean, and no specks of clay or glaze stick themselves onto the waxy surface on the bottoms of these. The wax itself can be quite tacky, and therefore they will pick up any bits of crud underneath them, which, if undiscovered, can cause blemishes on the bottoms of the pots once fired. Now that the glaze has dried out, when I rub over these tong marks, the higher points will grind away, and the dust that's created will simply fill the holes. This, by the way, typically works best with glossy glazes, and if you're working with matte glazes, even if you tidy up the tong marks really carefully, they can still sometimes be visible once fired. If this is the case, you have to apply the glaze in a different way, or position the tongs in places where their marks will be sort of hidden. On the outside, the first thing I do is shave over these tong marks. I typically start with a flat metal tool like this, or a knife, and then I use my fingertip, almost like sandpaper, to fettle over the rest of the surface. Essentially, I'm looking for any thick spots, and I'm grinding them back to be flush with the rest of the surface. There also tend to be lots of craters that cover the surface. I don't get rid of all of these, but I do tend to rub over the larger ones. These are created as water seeps into small holes on the surface, pushing air out, and creating a tiny bubble on the glaze itself. Truthfully, I should do a test to see if rubbing over these bubbles actually does anything, but maybe one of you already knows the answer to this. The next step is tidying the glaze off the bottom of the pot. I wipe it clean like this, as if there's any glaze underneath the pot, it'll stick it to the kiln shelf it's fired on. The chances are that a small bead of glaze wouldn't cause much damage, but if there's quite a lot left on the base, it'll stick the pot firmly down, causing damage to the pot as it's ripped away, and potentially damaging the kiln shelf itself, which is much worse. Thus, most of my care and attention is spent on tidying up the bottoms of these cups. I begin with a knife, and I glide it along the trimmed facet around the bottom of the cup. This acts like a guide, almost, as I simply fettle along this edge, and it leaves me with a lovely crisp finish, as there's a very distinct angle between the wall and the base of the cup. If instead the bottom edge was rounded, it would be slightly more difficult to carve neat, consistent lines all the way around. I then use a soaked sponge to remove any last remnant of glaze from the bottom, and again I run the sponge along that edge, to create as neat a line as possible where glaze and clay meet. It's when I first started doing this to my pots, as a student, that I felt they actually looked professional enough that I could sell them, and it was at that moment, I suppose, that I really got hooked on this craft, as I could finally see a way of making a living from it, as the pots themselves had reached a certain standard. This part of the process really is worth doing, especially if the level of finish on the rest of the pot is relatively high, and it matches the aesthetic of the cup itself. This is the level of cleanliness I'm looking for, as like I've said a thousand times before, the neater it is at this point, the better it's going to look once fired. The cup is then placed onto the wear board I wiped clean. This way nothing can stick onto the wax on the bottom. The other crucial part to this is simply how you hold the pot, because as this surface has dried out, and it's become powdery and soft, it's also become much more fragile, and it's susceptible to being chipped, or simply ground too thin. So when I hold the pot with my left hand, I'm actually gripping it really tightly so that my fingertips don't rub on the surface. At the same time, I don't want to grip it too firmly, as the glaze can fracture and flake off if I apply too much pressure. By the way, for this entire process, I'm again working over that basin of water, as this catches all of the glaze dust that comes off. It's also where I rinse the sponge when I'm tidying up the bottom, which is something I do relatively often, as the sponge becomes clogged with glaze quickly, thus becoming less effective, so I wash it out thoroughly and often as I work. You can see how much waste has accumulated, settled, in the bottom, and this is the amount saved in about half a year or so. It's also in this basin that I'll wash my hands and any tools along the way, again just to try and save as much as I can, instead of washing it away wastefully in the sink. By the way, for those wondering, the wax itself does just burn away during the firing, and provided you haven't applied too thick a layer, it shouldn't leave any residue. Here's that facet shown more clearly, which I glide the knife along. It honestly makes a huge difference in terms of how quickly I can clean these up. If you're new to this, you'll find that your left hand does get rather tired after spending a few hours gripping parts firmly, like so. It's sort of like learning to pull handles for the first time, where you keep a chunk of clay raised up for hours on end. It'll hurt and ache initially, but with time it's not too bad. Sometimes to clean surfaces more quickly, I use the entirety of my palm, but typically I only do this when I can tell that the surface is mostly very uniform, and I'm mainly just getting rid of the larger craters. When glazing pots, you also need to let it not pool too thickly anywhere, inside the pot for instance, or in the small gap on the bottom join of the handle where it meets the wall. As if there's too much glaze in one part, it can cause the entire pot itself to crack during the firing. I'm also careful to not let too much glaze accumulate on the handle itself, as due to the very steep angle of the underside of the handle, it can really melt and flow off this section. So if you notice the glaze is thicker here, it can be worth grinding it back a bit. When you throw and trim a pot, the goal is to often create a cross-section that's even throughout, and you can sort of think of applying glaze in a similar way, thus if it's really thick in one specific place, and much thinner everywhere else, then it can potentially cause issues. There is something else that I haven't spoken about, and that's how bisqueware is treated after it's been unpacked. If you handle the pot and you feel like it's dusty, then you should probably be washing your bisqueware, as otherwise, if you apply a layer of glaze over a dusty surface, or an oily one for instance, both of these can lead to something called crawling, which is when the glaze begins to separate from itself, leaving patches of bare clay underneath it. So don't handle any machinery or anything before you unpack a bisquenal, and you can wash your hands or even wear gloves if you want to be really careful. At the same time, not all clay bodies have to be treated in the same way. For instance, with this stoneware, I don't have to wash it, as it doesn't have a particularly dusty surface after being bisquit fired, whereas with the recent porcelain I've been making some pots with, I definitely have to, as when I unpack it, I can feel this dusty layer on the surface of the object. As for sanding bisqueware, that's personally something I never do. Well, I do it sometimes to correct features, or to define certain shapes on the pots I make with lines on them, but I don't think it's a particularly good habit to get into to sand all of your bisqueware all over, as in many ways you should be able to obtain a certain level of finish at the leather hard stage. Equally, sanding bisqueware creates an awful lot of dust. I suppose what I mean is that you shouldn't rely on sanding your bisqueware to get it to the finish you want, but at the same time, if you have a rim, for instance, that's particularly sharp or craggy, then I suppose there's no harm in sanding it smooth and washing it to get rid of the dust that would otherwise cover the surface, or simply do what I do and wet sand. Here's a better view of how I use a knife to carve that straight line around the bottom. I rest the straight portion of the knife onto this beveled edge and simply follow it all the way around, slicing through the powdery glaze. And once again, I have to reiterate that this is something that might not work with all glazes, as some, if they've dried into a stronger layer, might crack and come off rather inconsistently when you try and slice it away, and instead of the blade's knife just gliding simply through it, it might pull off much more glaze than you anticipate, so it's best if you can to go slowly and to not try and remove too much glaze in one go, as you could chip away more than you anticipated. And here's how one of these finished cups looks before firing it. It has a much more uniform surface, the base has been wiped clean of any glaze, and the tong marks have been scrubbed over, leaving a pristine, uniform surface. This is something I do for every single pot I make, and all in all, it adds a tremendous amount of time to the creation process of my pots, but it's a crucial step for my work, and it could be for yours too, but it really depends on the aesthetic you're going for, and ultimately the materials you're using. Eventually, all these pots can be placed into my Roda KG340 gas kiln. They can't touch for this firing, as obviously the powdery layer that coats them would melt and fuse the pots together as it turns to glass. The white layer that covers these kiln shelves, by the way, is bat wash, made from 50% china clay and 50% coarse alumina hydrate. This protects the shelves if glaze does run, but it can also sometimes stick to the bottoms of the pots, even if you've cleaned away all the glaze. What comes next is the nine-hour-long reduction firing to cone 10. This causes that powdery layer that coats the pots to essentially turn into a layer of glass that covers the entire vessel apart from its base, and at its hottest, the glaze almost becomes a liquid that covers the pieces. It becomes super cool when the kiln is turned off, and it loses temperature rapidly. The glaze and clay body can also release gas as it's fired, which can result in somewhat bubbled surfaces, which is why it's helpful to maintain a specific temperature towards the end of your firing so the glass can settle and even out. It's now about two days later, and the kiln is cool enough to unpack. Inside, the pots have now shrunk considerably, and the pinky red glazes you saw earlier have turned into this dark green as the iron it contained was chemically changed through the reduction firing process as the oxygen was stripped away from it. The white doesn't change colour too much though, but it does become a sort of darker grey tone. Despite the pots being fired, the process isn't quite finished, because as the clay shrinks, it recedes around the coarse particles of pre-fired ceramic material the clay contains, which we call grog. This means that their bases, despite being burnished smooth with the leather hard stage, become rough again, and thus need to be sanded smooth. This is something I do carefully, but the difference it makes is rather significant. You can hear how coarse and gritty the surface of clay is. So, to fix this, I soak this diamond pad, made by Diamond Cord Tools, in water, and then I lightly sand the bottom of the cup. Again, this isn't a mindless task, as if I grind away too much, it can discolour the bottom, which I'll demonstrate in a second. Essentially, all I really want to do is to get rid of the sharp texture on the bottoms of these cups. This way, they won't scratch whichever surface they're used on. Yet, if they are ground away too much, this is what happens. The surface colour is removed, and you're left with this grey tone, which I wouldn't mind if it covered the entire bottom, but when it's patchy like this, I don't particularly like it. Here are what the cups you saw me glazing look like once fired. They're now covered in a layer of glass evenly, although there are some natural changes in colour, especially where it breaks over the rim and the edges of the handle. Yet, there are no thin or thick patches covering these pieces, and the glaze application itself is very even, which is the look I'm going for. The more iron the glaze contains, the more dramatic the discolouration on those sharp edges. But what I'm really proud about is the clean, pristine bases these cups have, as it shows the care and attention that went into how they were glazed. Thank you so much for taking your time to watch, especially if you've made it to the end. I hope there were some things you found useful in this video, and that might make your glazing a bit more enjoyable. Otherwise, thank you so much for taking your time to watch, and I'll see you next time.