A quick fix for your overfiring manual kiln

Because one of the services we offer is kiln repair, we get calls on a daily basis about various kiln mishaps. Some of these inquiries are challenges, which we do our very best to meet; others, however, are totally the type of issues that most kiln owners are able to address themselves, once they know what's going on.  That's one of the great things about ceramics, right?  You wind up doing or making or fixing all of these things that seem like they might be really difficult, until you actually do them!  In the spirit of this sentiment, I've written a quick how-to for troubleshooting a fairly specific, but fairly common problem that we get calls about weekly -- your overfiring manual kiln.

Of course, there are many reasons as to why your manual kiln might be overfiring. You may need a new thermocouple, or you may have a burned-out element that is causing another element to work double-duty, resulting in a kiln hot-spot. However, the most common reason we have encountered is so simple, but so small you might not even think to check on it -- plus, it's a very quick at-home fix, so this certainly can't hurt to try as your first line of inquiry when attempting to fix your overfiring manual kiln by yourself.

Above, you see a pretty typical kiln sitter -- a Dawson LT-3, which is a very common model found on older kilns. Notice how the switch is in the 'down' position -- that's the position that switch will most likely be in for 99% of its existence. And that's fine! However, that is specifically what can lead to your kiln overfiring over time.

The reason for that is insidious gravity. Over time, that little metal plate -- the one that your kiln sitter switch latches on to when you set your sitter cone -- slides down in minuscule, imperceptible increments. 

This means, of course, that when your switch is flipped into the 'UP' position -- that is, when a sitter cone is in place and you're firing your kiln -- that plate has actually migrated UP too far. The higher the plate, the more your sitter cone needs to melt to allow the latch to release the switch, turning your kiln off. 

This fix is easy. Just using a teeny tiny Allen wrench, loosen the bold on the front of the switch, and with the switch in the UP position, slide the plate down very slightly, like a couple millimeters. Keep in mind the delicate nature of kiln calibration -- a very small distance can make a big difference!  At this point in the fix, you can mark the front of the plate with a mechanical pencil to note the position it is in. Then, if you are able to do a test firing with cones -- say, pop a few 06's into a kiln full of bisque work, as bisque temperatures have a little more wiggle room in terms of workable firing temperatures -- you can compare your plate's position with the 'true' heat inside of the kiln. You may need to fiddle with the plate yet again, but once you have it marked and the calibration seems good, you will find this easier to fix in the future, and something you can keep an eye on over time.

If you need a new kiln sitter -- or any part! -- for your kiln, check out our website's kiln part section here.  We should have what you need! And if we don't, just give us a call at 215-427-9665 and we can find it for you.

Ware Repair

Now that we've recovered from NCECA, we've started to tally the products that seemed to do well at the conference.  One product that we knew would do well -- and did -- is a product that we developed ourselves last year.  Ware Repair is basically our own version of a greenware or bisqueware 'glue' that can be fired, and our first time trotting it out to the public was at NCECA in 2013.  

Over the past year, we've performed additional tests on the product, heard a lot of feedback from customers, and used it quite a bit on our own projects.  On that tip, I figured this would be a good opportunity to share with you OUR experiences using a product that we make.  

Here we have a mug made by our tech, Rachel. This mug is great because it's literally a showcase of many of our products - from the translucent Cotton Candy glaze that you see on the upper portion of the vessel to the White Gloss glaze with a Black Wacky Wax design.  Notice along the upper interior rim there is a visible crack - this is a fracture that has been repaired with Ware Repair.  Rachel accidentally broke this mug after it had been bisqued, but she was able to repair it with Ware Repair.  The only reason the crack is visible here is because she opted to use a translucent glaze -- specifically to see how Ware Repair fared.  And hey! It fared well!

Totally functional.

So that's what Ware Repair looks like when you use it for a very realistic situation.  Our testing results often cause us to fabricate giant ceramic worst-case scenarios, though, which I personally love.  I mention this because below, I've included a few images of a pot that was smashed, then re-assembled using Ware Repair, while green, and was then taken through all subsequent phases of firing.  It's not necessarily pretty, but it is kind of awesome.  At least that's what I recall thinking when I cracked the kiln!

Before I cracked any kilns, though, I cracked the pictured pot into approximately 1,000 pieces.  Well, it was probably closer to ten pieces, but still. In the image above, you can see just how destroyed this form would have been, while it was still green. YES, any degree of ceramic instruction would dictate that you recycle such an accident, right?  However, there are always exceptions, and elementary schools seem to be the biggest source of those.  Over the years, we've gotten many calls from frantic teachers who are desperate for a way to repair broken student work. Sometimes things just get knocked around on a shelf; sometimes little kids just don't function as the best clay architects.  Whatever. The point is, is this has ever been a problem you've encountered, just keep a bottle of Ware Repair on hand in your classroom or studio and you won't have to worry about tears, guilt, waste, or regret.  

OK, that's a tall promise, but check out how this stuff works on gravity-based issues!

In the image above, you are looking at a handle that was completely broken off of the vessel in the green state -- repaired with ware Repair, it made it through bisque, and then through a cone 6 glaze firing, without falling off. Gravity was our toughest opponent as we developed this product, but as you can see, we really did our best to conquer it. 

If you have any questions about this product or any of our other products, please don't hesitate to get in touch -- as you can see, we use everything we supply, simply because so many of us are potters ourselves!  I'll leave you with one final awesome image of the mug that Rachel made, then broke, then Ware repaired, then awesomely glazed:

Mug by Rachel Sturino

Rachel, my birthday's in February.  Just sayin'.