Packing a Kiln Load of Pottery and Gas Firing in Reduction — Narrated Version

this week's longer video shows how i pack reduction fire with my gas kiln and unpack the very same kiln once it's cooled down a few days later the first step of course is preparing all the pots ready to put inside most don't need much done to them after their glazes have been cleaned up all of my lidded vessels like you see here must have their lids propped up using these tiny balls of wadding this material is made up from 50 china clay and 50 coarse aluminum hydrate although there are endless recipes out there i wedge the stuff up into a clay like consistency and carefully press each ball into a little disk which i then position around the gallery of the lid like you see here they only ever touch bare clay and they never actually come in contact with the pink glaze over top you see here if they do so the molten glaze will fuse with the weddings and they can be very difficult to remove but as long as they're only touching bare clay come the end of the firing they generally pop off quite easily with a little bit of pressure i then carefully place the lid on top of the jar making sure that neither of the clay components of both the lid or the jar are touching once the lid's on top i just push it down a little bit just to make sure it's held nicely in place i much prefer firing my lidded vessels with their lids and situ some potters fire the two parts separate in the kiln but i believe that if you fire them together any discoloration will happen equally across the two components as if they're meant to be together and as the two pieces kind of sit into each other and hold each other in place there's very little chance the lid or the body of the jar will warp plus if you fire the two parts together you end up with a lot more space in the kiln you can actually use for other pots wedding has all kinds of uses too it isn't just for propping up lids you'll find that wood firing potters use a tremendous amount to prop their pots up on the kiln shells so the molten ash and glazes don't fuse the pots to them i also use it to support my cones which are these coloured spikes you see me breaking apart here these are called pyrometric cones these are placed inside the kiln as it fires opposite the spy hole in the door so i can look at them during the firing they measure heat work which is heat over time and each one bends over at a very specific temperature and it's by these that i know when to turn the kiln off so in this instance i'm using cone 8 cone 9 and cone 10. as they melt they bend over in the direction they're facing and this happens between 1 247 degrees centigrade to about 1295 degrees centigrade so they're tools really measuring tools which i can use once per firing i place two cone packs in each firing but i always make a whole lot together like this and then i can keep them stored away ready to use next time i fire you'll see them in various states throughout this video inside the kiln and what they look like afterwards too here i'm just cutting away excess wadding there's no point wasting it so i tried to collect as much back as i can to use for other things warding isn't the only thing you can use for this process you can use clay too you've just got to make sure that when it comes to actually firing them that the clay or the wadding is totally dried out first otherwise you can risk the cone packs literally blowing up as the moisture released from the wet clay oils inside itself and finally explodes that's more or less all the preparation i do for the kilns and once all my jars are wadded up all my cone packs are made it's ready to start packing i'm currently using a kg 320 rhoda gas kiln you can see in these shots the flues at the back where the flames will eventually travel up and down out of these each pot is carefully positioned inside making sure that absolutely none of the pots are touching each other if there are two glaze sections that touch as the kiln fires the glass will fuse together and the only way to separate them afterwards will be just to smash them the bases of the pots themselves don't have any glaze on so there's no risk of them fusing to the kiln shells you'll notice in this base layer that there's a few pots that have already been fired these are pots that initially didn't quite get to temperature so the surfaces are quite dull and boring so i simply put them back in the kiln for another firing which not only fixes them but sometimes makes them even more interesting than the other pots themselves as i'm putting the other shelves in here you can see the comb pack just below it's positioned in such a way that i'll be able to see them through the spy hole in the kiln's door during the firing with this kiln i have to pack the base layer a bit more open than i would like you'll see that as i go up the layers become a lot more dense but if i were to pack the bottom layer like this it just wouldn't reach temperature these are kiln props they come in all shapes and sizes and they're what i use to prop up one shelf from another inside the kiln i try to have as many different kind of shapes as possible some thinner some thicker that way i can pack my kiln really efficiently and fit the most in in a really full firing i'd say i can fit about 150 pieces in total inside you only need to position three props per layer so it acts like a tripod which is very stable once i've positioned the props i simply try and fit as many pieces on each layer as i physically can it can sometimes take numerous attempts until you find the best layout the one that's the most efficient and allows you to squeeze in as many pots as possible when reduction firing the less empty space there is in the kiln the easier it is to achieve a good reduction atmosphere this is something i'll go into in a lot more detail later on once the kiln is packed it's always a bit of a jigsaw getting everything put inside but it's a process i like surprisingly a lot getting the shelves neatly in place can always be a challenge too especially when the pots underneath is so tight to the shelf above as your hands that are holding the shelf very little room to escape from after it's been positioned it's slow steady work and you need to be careful the bricks from which the kiln and door are built from are very fragile they're very light so if you were to bash one with a kiln shelf you can leave permanent damage to them quite easily the types of glazes you use also play a huge role in how easy a kiln is to pack this would be different for everybody though of course as each potter's glaze recipes are different the glazes i use become incredibly fragile at this stage even just knocking them slightly is enough to cause them to chip and their powdery surface is constantly coming off on my fingertips so as i pack pots and change between different colors of glazes i constantly have to wipe clean my fingertips in between and clean the different parts by now you'll have gathered that this is a front loading kiln as compared to say a top loader where you pack the pots top down and you have a constant bird's eye view of what's going on with these front loader kilns it can be hard to judge the distances behind the pots themselves so as i position each pot i try to hold the pot with my fingers on the back of the vessel and as i slide it back i can feel when my fingers touch the pop behind it i also even wiggle the pots in place sometimes just making sure that it doesn't hit anything in the surrounding area i could of course put my whole head inside the kiln at this stage but as you get to the upper levels there's simply no room to do so here you can see some lidded jars propped up with weddings like shown in the beginning of the video these i move around very delicately as the weddings can dislodge and even fall inside the pot and if you don't notice that there's a high chance they'll get fused in there forever with all the molting glaze the shelves become more and more awkward to squeeze inside the high you get as there's little room above to work with so like any skill packing a kiln is like learning to throw or learning to pull handles the more you do it the easier it gets the best thing about packing these top layers is that there's no props getting in the way or that you have to work around so i can always squeeze in far more pieces i'm still surprised by just how many pots i can fit inside this kiln even after a year of using it 320 cubic foot really is quite a lot generally speaking the top level is where the kiln is the hottest so i like to put my larger pots up there as they're generally the pieces that will benefit most from having more heat i don't mind re-firing a few smaller pieces every now and then but having to refine larger pieces can be a lot more costly so they always get the prime positions one thing i always have to remember on this layer in particular is that another pair of cones will have to be placed near the front so they're viewable through the spy hole in the kiln store instead of checking my height of pots against the props inside the kiln i often take props outside of the kiln and check them against the pots around the studio it can help give you a better idea of what can actually fit in some of you potters watching this might be wondering why my props are such red colors and it's simply due to them being reduction-fired they're white and new fresh from the box but after a few firings they really deepen in color but it's nothing to worry about the walls and the door of the kiln are taking on the same coloration too and every now and then i have to close the door and i shine a light through the spy hole just so i can make sure the cones are really easily visible it's a nightmare when they're really difficult to see during the firing and that's happened to me previously so nowadays i'm extra careful about how i place them as the cones and these types of firings are completely mandatory i'd be lost without them this type of gas kiln isn't programmable and you can't just turn a button and have it fire overnight i have to be there the entire nine hours so it's important to get everything right depending on what's going inside the kiln the entire process can take an hour or two to pack if it's a really complicated one with lots of varying pots of different heights and widths the whole pack can take a lot longer to complete there's something immensely satisfying about this process though it really is like one big giant game of tetris and it certainly teaches you a life skill of how to fit as much as you can into small spaces this shelf right at the top is probably the hardest to get inside often i just have to place it roughly and then once it's there i can reposition it in kiln sci-fi previously i've had to worry about which color of pot goes where as those that were close to the burners where the flames were jettisoned inside the kiln would often be slightly discolored sometimes even oxidized but this new kiln fires so incredibly evenly that it really doesn't matter the top the bottom the sides it all gets the same level of reduction and 99 of the kiln gets to the right temperature and that's the kiln packed in goes the final little white jar and i'll now wait until early the next morning to start the firing my firing takes about nine and a half hours from start to finish so i like to start early at about 7am in the morning i start by lighting each of the four burners and put them on their lowest setting whilst of course the doors are open as you never want to fill the chamber up with gas and then light it as that can cause things to explode so i always light the kiln first and then close the doors screwing it tightly shut i fire my kiln from a main supply using natural gas which is great as i don't have to worry about moving bottles of propane around or ever running out so for the first couple of hours i simply keep the kiln on a nice very steady slow climb if you take it too fast at the beginning you can really risk blowing up a few of the pots inside you might want to pause it here but this is a graph of one of my firings and it shows the steady rise up to the reduction temperature of 860. and you can see how the temperature thereafter sort of climbs at a slightly slower rate than it did previously below this plotted chart are all my manual inputs so every half hour i'm plotting the time how many hours it's taken the temperature the gas the air and the dampers it's always a bit daunting seeing all this information plotted out from a firing that's been completed but after doing one or two of them yourselves it really isn't too complicated figuring out when to set the reduction can be the hardest thing and every single type of gas kiln fires differently so it can really take a few attempts before you really hit the nail on the head and get a perfect firing once my parameter is reading 860 degrees it's time to set reduction i do this by increasing my gas pressure to 10m bar and also increasing my compressed air pressure to bar and finally i closed the dampers to about halfway closed and this upcoming clip for anybody who's interested is the noise my air compressor makes it isn't all too bad it only goes off every 10 minutes or so and only for 45 seconds of time so you get used to it quickly so i should use this time to explain what a reduction firing is it's a process that can only be done with a gas kiln and you essentially starve the kiln of oxygen so by sliding the dampers closed on the back and by increasing the gas pressure significantly and cause the internal atmosphere to burn really inefficiently as there just isn't enough oxygen inside for it to burn properly and as fuel needs oxygen to burn it ends up reaching inside the clay and the glazes into the molecules and it strips out the oxygen molecules which bubbles to the surface bringing iron with it resulting in iron speckles covering the surfaces of these pots and causing the greens and the blue tones to appear if i were to fire my pots in an oxidized atmosphere one with plenty of oxygen they come out almost putrid in yellow and not very nice at all these flames you see are a good indicator of a strong reduction inside the kiln the flame pops out as it's searching for oxygen to burn efficiently with these are the same spy holes where i can see the cones from too which as the kiln finally reaches temperature will look something like this as the temperature keeps rising and i keep the reduction going the flames that emit from the kiln become redder and redder a sign of incomplete combustion inside and here i'm just removing the spy hole just to take a peek at the cones inside to make sure i know what's happening as the temperature increases the rate at which it climbs slows down so periodically i just move the damper open fractionally and this is enough to get it going up again and that's literally the only input i do until the firing is complete there's nothing else i have to touch i just have to make sure to check the cones regularly so i don't miss them bending over but you can sort of judge temperature simply by the color inside it gradually changes from a red to an orange to be yellow and then finally to a bright white and when it's really bright and white inside you know it's time to start checking your cones more regularly which at this temperature i do by opening the spy hole and blowing inside this briefly cools down the cones and shows their edges which can show you exactly how bent over they are ideally i want cone 10 on both bottom and top to be touching toes and only notice this when i watch the footage back but it's interesting to see how as i blow in the flames coming out of the flues at the back change and once my cones have bent over to where i want them which is at approximately 1290 degrees centigrade it's time to turn the kiln off which is always followed by a blissful silence after a long noisy day in the studio where the air compressor and the kiln constantly on as soon as it's off i crash call the kiln back down to a thousand degrees centigrade i do this by opening up the dampers fully and by removing the two bungs from the spy holes this helps the pots to retain their sheen as well as maintaining their bright intense colors and this little clip here you can just about see the cones through the spyhole so this is what i'm looking for when i look through them and finally i slide the dampers closed fully and i put the two bungs back into the spy holes this is now about a day and a half later and the kiln reads about 150 degrees centigrade which is plenty cool enough to open it this is always such an anxiety-inducing moment is even though the firing went well you never know really what's going to be inside the faint tinkling noise is the sound of the glaze contracting over the clay body underneath it only lasts for about an hour or so before stopping for good as usual the pots on the bottom are very much handleable straight away whereas those on the upper shelves are still scorching hot unpacking is a slow process i look at each pot as it comes out assess them see whether they make the cut and put them aside the change they undergo inside the kiln is always so drastic they shrink they change color they're now glassy whereas before they were matte it's a long process from being thrown and finished to finally being fired like this weeks or months so it's always a big relief to get a good kill no doubt once the top is cooled down sufficiently i'll begin to unpack it and i'll also keep the two cones as they're good indicators of how the kiln fired how even it was and what the temperature was like so i have a whole collection of these so far from every firing i've done in this studio after each pot is being inspected i lay them all out like this and prepare the tidying up process first all the jars and all the lidded forms are separated which can take a few knocks and a good squeeze to get the two pieces to loosen up it's the jars that require the most work to tidy up whereas most of the other pieces simply have their bases sanded which is a process you'll see towards the end of this video but first i more or less empty the entire kiln save the bottom layer there's so much to look at and process it can take a good few days to really see everything properly and taking photographs of each one from my online shop really does help once the kiln has been totally unpacked i labeled the two cone packs and i placed them up here although i think i'm quickly going to run out of space all of these pieces fit inside the last kiln load to give you a good idea of how much can fit inside once it's all unpacked i can finally begin the finishing procedures for the jars which is a simple process really and one i learned from lisa hammond at maise hill pottery during my three year apprenticeship with her i rub over chemical valve grinding paste which is essentially carborundum suspended in gel it's placed in between the gallery where the lid meets the body and the two are ground and placed together vigorously and with enough elbow grease it can be glassy smooth by the time you're finished it can also be used if the lids don't quite fit properly it's coarse enough that you can really grind and sand the lid right into place so it fits absolutely perfectly it can take a long time to do a whole batch of pots but it's well worth it as the glassy smooth finish just feels so good here's the difference between the two and it'll feel even better once all the gritty residue has been washed off which i get rid of with just some hot soapy water every other pot receives this treatment which is the base just being simply ground with a tiny bit of wet and dry sandpaper just enough to remove the really coarse bits of sand in the clay body and that's it although multiplied by many hundreds of pots it can be an arduous process but one that's well worth it once you get to hold the finished fired pots in your own hands you

Channel: Florian Gadsby

Views: 33,415

Rating: 4.9715157 out of 5

Keywords: pottery, how to make pottery, Florian Gadsby, floriangadsby, handmade pottery, ceramics, clay, wheel thrown pottery, making pottery, making ceramics, handmade ceramics, how to fire pottery, firing pottery, firing ceramics, gas firing pottery, reduction firing, gas firing, how to reduction fire, reduction atmosphere, celadon glazes, how to fire celadon glazes, gas fired ceramics, how to gas fire pottery, how to gas fire ceramics, gas kiln, pottery kiln, ceramics kiln, kiln

Id: BZSnnhjntvA

Length: 19min 56sec (1196 seconds)

Published: Sun Nov 29 2020