synj00 Posted November 11, 2014 Report Share Posted November 11, 2014 I got lucky with this one and I wanted to post this as a reminder to folks to always check and make sure the kiln is FULLY in order before firing. My blog is about success AND failure so you get to learn from my mistakes. If I can help prevent one accident it is well worth the embarrassment. http://dreamsofearth.wordpress.com/2014/11/11/dont-let-this-happen-to-you/ Link to comment Share on other sites More sharing options...
neilestrick Posted November 11, 2014 Report Share Posted November 11, 2014 Good reminder! I see melted cords all the time. The zip tie solution is just fine. Link to comment Share on other sites More sharing options...
Benzine Posted November 12, 2014 Report Share Posted November 12, 2014 Neil, I'd imagine you have some interesting stories, about things that have happened to kilns. Here's a question, I've talked to two teachers, who have had kilns not shut off, and melt the wares. Have you run into this much? I think both cases, it was a kiln sitter, where the cone wasn't set, or didn't melt properly. Link to comment Share on other sites More sharing options...
neilestrick Posted November 12, 2014 Report Share Posted November 12, 2014 The kiln sitter is a mechanical device, and therefore has the possibility of not working. If any parts of the sitter stick, then it won't shut off. That's why they started putting backup timers on the sitters. Of course, if you set the timer too long then it doesn't do any good, and it's also possible for the timer to fail since it is a mechanical part as well. The only way to be 100% sure that a sitter kiln shuts of properly is to be there in person to check it. If you're not willing to do that then you have to accept that at some point your sitter will possibly fail and you will ruin some pots and/or the kiln itself. The worst I have ever seen was a firing where a post or pot fell over onto the sitter tube and prevented the sensing rod from dropping and shutting off the kiln. It was an old sitter and didn't have a backup timer, so it kept on firing until the pots melted, then kept on firing some more until the shelves warped like potato chips and collapsed into a pile at the bottom of the kiln. The kiln was destroyed. The whole bottom half of the kiln was a melted mass of shelves and pots fused to the wall bricks. Luckily it was a really old kiln that needed to be replaced anyway. For a digital kiln to over fire, a relay has to stick in the 'on' position, and the kiln has to be packed in such a way that enough heat is trapped in the section controlled by that relay that it can over fire. A section probably can't over fire in a cone 6 firing, but it is theoretically possible that in an earthenware firing a section of the kiln could over fire a little bit. In a two section (18" high) kiln where there are only two relays, one sticky relay can cause the entire kiln to over fire a little. I've seen that happen. I have never seen more than one relay stick 'on' at a time, however I have seen two relays fail 'off' at one time. Again, the only way to be sure is to be there to check that it has shut off. Link to comment Share on other sites More sharing options...
Pres Posted November 12, 2014 Report Share Posted November 12, 2014 Old L&L did it one time, setter was positioned between two sections. Somehow top section got knocked slightly out of align changing the angle of the drop plate on the outside, when the cone bent, the rod dropped but the drop plate stayed resting against the setter on the outside. I usually have the timer set to within 30 minutes of the cone on it, so no melt down, but plenty of overfired bisque. Link to comment Share on other sites More sharing options...
Benzine Posted November 12, 2014 Report Share Posted November 12, 2014 One of the teachers said, they got a new kiln. The other said they continued to use it for a while, and just had a mass of melted clay on the bottom of the kiln. Since they only fired low fire, the mass never got hot enough, to melt again. Sometimes you have to work with what you have.... I'm definitely more cautious with my kiln, after being on here for a while. I now close the lid, when not firing, which I hadn't done previously. I also shut the kiln off, and shut off the electrical power supplying it, when I know it won't be used for a while. I have a nice kiln in my classroom, and want to keep it that way. Link to comment Share on other sites More sharing options...
Mark C. Posted November 12, 2014 Report Share Posted November 12, 2014 They could chisel off the mass and flip the kiln floor over to new side. Mark Link to comment Share on other sites More sharing options...
Guest JBaymore Posted November 12, 2014 Report Share Posted November 12, 2014 Years ago (like 15-20 now I think!) I did a survey (via the CLAYART listserve) relating to "kiln disasters" for a major presentation I was doing. There were a HUGE number of electric kiln "disasters" reported to me. Way more than I expected. Very few gas kiln ones. There are more electric kilns in use than gas kilns... so this is skew is a bit what one would expect.... but it still was amazing how many fires and near fires got reported to me. The main disasters that were reported from electric kilns involved a fire or a near fire at the junction box on the wall where the kiln connects to the stuidio/house wiring. A huge proportion of THOSE related to kilns that were not hardwired into the electrical supply (ie. plug in kilns). The issue in both cases is mainly the eventual slow corrosion of the connections combined with the sustained high amperage draw of a kiln. The plugs and socket corrode (surface oxidation). Corrosion equals resistance to electrical flow. resistacne to flow equals heat energy created from electricity (just like ion the elements). Heat generated where you don't want it...... equals problems. If put in correctly the hardwired ones get an anti-corrosion compopund on them. And are TIGHT connections. Plugs and sockets need checking regularly. Be careful .... literally LETHAL voltages present when doing this work. If you don't know how to do this safely....... hire a pro. (do a Google search on "lock out / tag out" procedures too!) CHECK those kilns folks. Routine maintenence is the word of the day. Having a "pilot chacklist" to use as a standard reference before a firing is a good thing. Works for aircraft pilots. It makes sure you don't forget something (like the pair of pliers inside the kiln!) best, .......................john Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted November 12, 2014 Report Share Posted November 12, 2014 I always make sure to double check the cables position, even then when I am 100% it is nowhere near I make myself check once more before locking up the studio. It is an expensive thing to melt! Link to comment Share on other sites More sharing options...
neilestrick Posted November 12, 2014 Report Share Posted November 12, 2014 They could chisel off the mass and flip the kiln floor over to new side. Mark In my experience, when low fire pots melt down into blobs it's usually impossible to get them off without taking very deep chunks out of the floor. Better to work around them if possible. Link to comment Share on other sites More sharing options...
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