Somerville Posted February 17, 2019 Report Share Posted February 17, 2019 First post ever to a ceramic forum. I really hope you can provide some clues. I have been firing smooth stoneware slip-cast plates with a matt transparent glaze to 1250 Celsius in an electric kiln. One firing- went very awry. Does anyone have any clues as to why the following could have happened? and what it might be? (I'm thinking copper oxide). The photo shows the worst affected kiln shelf: the top shelf. The spots go down the side of the kiln and onto the base as well as a couple of spots on plates on various shelves below. There is also an area of spots on the inside of the lid right above the densest area seen in the photo. I share a studio and kilns with a number of people. I am perplexed about how this may have happened spontaneously but thought I should seek more experienced practitioners for advice. Please help! Link to comment Share on other sites More sharing options...
liambesaw Posted February 17, 2019 Report Share Posted February 17, 2019 Wow looks like something exploded, I'd try to get it off the soft brick, can't be good. I don't think this just happens, but it's probably not sabotage, maybe an accident nearby? Could the kiln have been open when someone was mixing glaze or something? Link to comment Share on other sites More sharing options...
hitchmss Posted February 17, 2019 Report Share Posted February 17, 2019 Im not inclined to think that it was sabotage; for two reasons, Id like to think that your studio mates are not that nasty, and that if it was I who was doing the sabotage, I would have really done it. I mean if you rob a bank, you dont just take $20. Its a strange pattern and Id agree that it looks like copper/copper glaze splattered. There are a who slew of ways that I end up with clay and glaze splats all over my studio, all the way from the floor, to the ceiling. How you ask.....?! Drop a open glaze bucket down too hard and a little glaze rocket comes flying out...mixing dry materials and you sneeze and accidentally toss dry materials everywhere....drop a pot into a glaze bucket by accident....Way too many scenarios to try and decipher. Id use a small needle tool or something similar to pick the small spots off your kiln brick so they dont eat further into the brick. The plates are relatively flat so maybe with a grinder/sandpaper you can remove the stuff on your pots Did you load the kiln? Were the kiln shelves set onto a table that had glaze/glaze materials on it....stuck to underside of shelf, fell onto pots below? Did you ask studio mates what happened? Id fix the errors and move on. If it was intentional stuff will continue to happen, and hopefully it doesnt. Hopefully it was an accident and all your studio mates will live happily ever after Link to comment Share on other sites More sharing options...
Somerville Posted February 17, 2019 Author Report Share Posted February 17, 2019 The kiln is separate from our work spaces. And the shelves are stacked in that room on their sides against the wall when not in use, although I had just unloaded the kiln and repacked it myself. The worst contamination is on the top which had no shelf above it for chemicals to drop down from. It also is on the kiln shelves themselves and therefor has to have happened once the kiln was packed. The material is embedded into the glaze making these plate unsalvageable. Also as it is an unknown chemical, these cannot be used for food. Sabotage? a little tongue-in-cheek I admit, but I do believe it is naive to assume everyone has good intentions all of the time. If it was an accident I would still expect someone to tell me what happened. I'm not obsessing: I have made over 100 plates since this firing. I thought it would be worth while getting some other opinions in case there was a plausible kiln malfunction. Link to comment Share on other sites More sharing options...
Roberta12 Posted February 17, 2019 Report Share Posted February 17, 2019 Has there been another firing in this kiln since "the incident"? The only other thing I can think of besides what @liambesaw and @hitchmss suggested , would there have been something on your apron or shirt or coveralls that fell into the kiln?? (you just have to know many of my comments come from experiences!) Roberta Link to comment Share on other sites More sharing options...
Min Posted February 17, 2019 Report Share Posted February 17, 2019 Sorry to hear about the possible sabotage. I can't think of any kiln malfunction that would do that. Copper glazes can spit but not to that extent. Did you even have any of the dark glaze on the pots in the kiln? I guess in a worst case scenario of it happening again you could install a camera to monitor the kiln area, although someone mean spirited enough to do that would probably just find another way to cause damage. Welcome to the forum. Link to comment Share on other sites More sharing options...
Mark C. Posted February 17, 2019 Report Share Posted February 17, 2019 Whats the shelve bottom above the plates look like??The kiln wall has some spots as well. I suspect dirty shelve or these spots could have been on the pots where they are stored glazed or as other mentioned a pot on nearby shelve exploded or a piece came off.Next time cover your glazed wear if it stored in an area that it could get contaminated .Since the shelves have spots that shows more of a chance that it happen above tis shelve in fire-that kiln wall also has spots.Those should be removed from the soft brick carefully. Since you are not loading no telling what happened-I think its an accident ether way Link to comment Share on other sites More sharing options...
Babs Posted February 17, 2019 Report Share Posted February 17, 2019 Lucky no spots landed on elements.... Kilns away from work area. But in the same room? Splatter can carry a long way.ditto Roberta here. Kiln sits with lid up when not in use? Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted February 17, 2019 Report Share Posted February 17, 2019 The spatter seems to have a bit of a direction to it. Is the lid typically cracked at the beginning of the firing for ventilation? I wonder if something (glaze material, some kind of other metallic something) got blown in by accident? Thats really weird. Link to comment Share on other sites More sharing options...
oldlady Posted February 18, 2019 Report Share Posted February 18, 2019 somerville, these spots are larger than the ones i had on my top shelf but i wonder if they have the same origin. ( if they are copper, you will need to do what sam hitchman suggests above.) if you look at the metal band around the lid on the kiln, can you scratch off bits of metal with your fingernail or a brush? i have cleaned the band on my kiln numerous times and finally came to the conclusion that i cannot prevent the bits from falling so i put a barrier between the lid and the kiln. i used a large piece of newsprint from a roll of wrapping paper and placed it on the top of the brick sides of the kiln just before closing the lid. it covered the whole thing. as the lid comes down, black bits land on the newsprint and i can blow them away without any trouble. i left the paper in place and it burned up without any problem. i tore it off and the only part left was the tiny bit that charred and stayed on top of the row of brick. unfortunately, i foolishly gave that paper to someone who needed some for wrapping. i then used a second roll of thicker white paper and did the same thing. every bowl and pot on the top shelf wound up with white lumps inside. i always knew that clay was used to make magazine paper white but it never occurred to me that clay was in any white paper and would melt into the glaze of my pots. going to find a new roll of newsprint. Link to comment Share on other sites More sharing options...
Somerville Posted February 18, 2019 Author Report Share Posted February 18, 2019 Dear Roberta12, Min and Mark C., I loaded the kiln myself, the plates were glazed that day so weren't sat around unattended. I do not own any copper materials and no other glaze was used in the firing that contained any coloured compound. The kiln is in a separate room and we have our own rooms with doors, the kiln is by the open door but shielded by the wall and the lid is generally down when not in use. The lid was also closed fully from the beginning of the firing. Calliee Beller Diesel - I do agree. I also think if a powder went in when the air in the kiln was hot the convection currents would have circulated the powder down, in and onto lower shelves, which is what can be seen. Images are of the second shelf down, the base of the kiln, the third shelf down and the last shelf. Link to comment Share on other sites More sharing options...
Babs Posted February 18, 2019 Report Share Posted February 18, 2019 Where is lid hinge in all of this. I'm with Old Lady in this. Lid and brick tops . Who used kiln prior to your use? Colour of glaze in last firing..prior to your use? Possible dry glase left sitting on kiln brick edge which you brushed into kiln with sleeves and hands... Link to comment Share on other sites More sharing options...
Min Posted February 18, 2019 Report Share Posted February 18, 2019 That picture of the kin floor looks like spalled bits from a thermocouple, are any of the protection tubes damaged or were they recently replaced? What condition is the metal band in on the lid and the jacket around the spyholes? Any flakey bits come off if you brush the metal? Do you have a fan running by the kiln? Link to comment Share on other sites More sharing options...
fergusonjeff Posted February 18, 2019 Report Share Posted February 18, 2019 Where are you located? If you are able to ship a piece to me I would be happy to take a quick look and see what the substance is. I have XRF equipment that is very quick at determining qualitative bulk chemistry. It is really easy to identify most basic metals (Cu, Co, Ni, Fe, Mn...) Link to comment Share on other sites More sharing options...
Somerville Posted February 18, 2019 Author Report Share Posted February 18, 2019 There is heat damage on the lid band but not to the point of flaking. Spy hole is always plugged as you can’t physically take it out without removing the metal surrounding the hole. I used the kiln before this firing. With exactly the same type of things being fired. No coloured glaze. I could understand if it was the person before me leaving residue but to have a perfect firing by me before this one really makes it hard to understand. To my knowledge the thermocouple has not been changed recently. I am in the UK. I’d be interested in knowing what it is Fergusonjeff. Where are you? Link to comment Share on other sites More sharing options...
neilestrick Posted February 18, 2019 Report Share Posted February 18, 2019 Not related, but your elements are not looking good. There are sections with wide spaced coils, and sections with tight coils. If you have to stretch them during installation, stretch them over the longest area possible, so you have even coil distribution. That will give you even element wear and even heating. Link to comment Share on other sites More sharing options...
Mark C. Posted February 18, 2019 Report Share Posted February 18, 2019 I think it all looks like iron spots-for sure some are coming from the unproteceted thermo couple. As Neil says those elemnts are jumping out of the groves-maybe rust from lid band(show us a photo of that band) iron spots are on the shelves now where they before you loaded as well.?? What does the underneath non-washed side of the shelves look like are they spotted or clean??? Iron is easy to get on things and hard to get off. Is there rust anywhere on outside or lid of this kiln?? My guess is yes. Link to comment Share on other sites More sharing options...
Benzine Posted February 19, 2019 Report Share Posted February 19, 2019 17 hours ago, Mark C. said: I think it all looks like iron spots-for sure some are coming from the unproteceted thermo couple. It definitely does look like residue, from the thermocouple, but I don't have any protection around any of the three, in my kiln, and they have never done anything like what was posted in the photos, or even affected any of the projects in the kiln. I've put things directly under them before, and still nothing like that. So it's definitely odd. At the very least, something from the kiln is dropping bits of oxidation or other such debris in there. Wouldn't hurt to give the kiln a good once over with a vacuum; underside of the lid, between the lid and the banding, element grooves, etc. Link to comment Share on other sites More sharing options...
neilestrick Posted February 19, 2019 Report Share Posted February 19, 2019 It's a pretty big spread of material for a thermocouple. Usually they just drop stuff right in front of them. I've never seen one blow up and spread it all over like that. plus it looks like the thermocouple is sheathed? Link to comment Share on other sites More sharing options...
Benzine Posted February 20, 2019 Report Share Posted February 20, 2019 On 2/19/2019 at 9:00 AM, neilestrick said: It's a pretty big spread of material for a thermocouple. Usually they just drop stuff right in front of them. I've never seen one blow up and spread it all over like that. plus it looks like the thermocouple is sheathed? Good point! It's almost like a small bit of material "popped" off from something during firing. That one plate, in the top right, of the first photo seems to be the epicenter. We need a crime scene technician here, to chime in... Or someone who just watches CSI a lot... Link to comment Share on other sites More sharing options...
liambesaw Posted February 20, 2019 Report Share Posted February 20, 2019 Enhance. Link to comment Share on other sites More sharing options...
shawnhar Posted February 21, 2019 Report Share Posted February 21, 2019 My guess: Powder form contaminate was sucked in by one of the vent intake holes. That's not a splatter pattern and was obviously spread to the lower shelf via air current. Link to comment Share on other sites More sharing options...
Benzine Posted February 21, 2019 Report Share Posted February 21, 2019 20 hours ago, liambesaw said: Enhance. That is only effective, if you proceed it with "Zoom and". Link to comment Share on other sites More sharing options...
Mark C. Posted February 21, 2019 Report Share Posted February 21, 2019 I think a small group of masked men snuck in, in the middle of the firing-They maybe where armed or NOT. one was at the door keeping an eye out and two where working the kiln. One was in car waiting outside-one had locksmithing skills -one wqs a potter who knew how to screw up only this layer of pottery and no other shelves. They where recently discovered and exposed as the Pottery Hit Squad.No job to big or small-wreking havoc anywhere on the planet. They can parachute in or dive out of a submarine anywhere they are needed . Sabatoge? thats the name of the game for these guys-also the name of this pots and soon the name of a new board game.Look for the ads in the back of CM soon You to can guess who did what with whom and what kiln ?? You can guess the electric level 4 shelves with iron filings or a bag of copper oxide. Link to comment Share on other sites More sharing options...
liambesaw Posted February 21, 2019 Report Share Posted February 21, 2019 9 minutes ago, Mark C. said: I think a small group of masked men snuck in in the middle of the firing-They maybe where armed or NOT. one was at the door keeping an eye out and two where working the kiln. One was in car waiting outside-one had locksmithing skills -one wqs a potter who knew how to screw up only this layer of pottery and no other shelves. They where recently discovered and exposed as the Pottery Hit Squad.No job to big or small-wreking havoc anywhere on the planet. They can parachute in or dive out of a submarine anywhere they are needed . Sabatoge? thats the name of the game for these guys-also the name of this pots and soon the name of a new board game.Look for the ads in the back of CM soon You to can guess who did what with whom and what kiln ?? You can guess the electric level 4 shelves with iron filings or a bag of copper oxide. Mrs peacock in the kiln room with the granular magnetite! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.