Bill Kielb

Pictures for sure for ideas. One experience - Not all clear glazes melt well over underglazes so the underglazed decorated area can be locally refractory. The end result for this defect, bumps, orange peel, glaze that does not cover and melt well to a smooth finish. Often mistaken as over fired and bubbling. Additionally if heavily underglazed, when applying glaze over the top the underglazed area is far less absorbent than naked bisque so it can be hard to apply glaze over the top evenly. Spray applying overglaze and drying is one way to get a pretty even coat over the entire ware. Pictures for sure here as there can be other reasons for sure. Most underglazes need to be tested with their overglazes in the manner they will be used to be reasonably sure the combination works as intended.

Hard to know the formulas for sure of commercial glazes but there are many sources for glaze recipes. Glazy.org is one web resource. Making glazes for many potters is a thing though, often to save on the high cost of commercial glazes but also often to design glazes that are very durable, to their coloring and finish preferences. You can browse glazy (and others) for something that might be similar.

Whatever you do, I urge testing. Many of these things folks mentioned above can cause significant acute effects in super small quantities. So small you can’t smell them, but may have acute effects on peoples ability to smell, mood swings, etc..…..you have symptoms, you really want to know the origin of the symptoms. It may have nothing to do with how things smell to folks not affected or how the contaminant smells in strong concentrations. One of the items mentioned above, Perchloroethelene (dry cleaning fluid) has varied effects on humans in doses too small to smell. Your symptoms appear severe, it seems like real tests are important for discovery. If discovered and if you are seeing a doctor, they can often do tests of the concentration in your blood. That is often how these things are discovered. My thought: Please get some testing, please see your doctor. You will never ever be able to smell parts per million or parts per billion of perchloroethelene. Hopefully it is something simple - best way I believe to understand though is testing.

Copper is interesting and there are limits but most often found in an industrial setting when testing for heavy metals.. Sounds like you need a real environmental air test and lab analysis to figure this out ……… then figure out the source. Clay may or may not be a concern here so a real test with real quantities of constituents likely is the best way to know with reasonable certainty. For now, no exposure or very limited exposure until you can correct seems important. Adding cleaning chemicals, moisture etc… can amplify effects. I suggest get a real test and lab analysis ……. on paper by an industrial hygienist or equivalent.

The 2280 on the side of the kiln likely means it is rated cone 8. Folks who fire to cone 6 generally buy a cone 10 rated kiln. The higher rating simply gets them more firings on a set of elements than a lesser rated kiln. Your kiln with new elements ought to get you cone 6 firings, not as many as cone 10 rated but a fair amount. You have a manual kiln, great for learning! If you search the web you likely will find helpful information on manual kilns. Here is a YouTube video I spotted for firing a manual Evenheat kiln. https://youtu.be/AFI5zYdRJ8E?feature=shared

Looks good - do you fire or just learning to? What cone do you fire or hope to? The Evenheat manual Is probably available online, might be a good place to start. Study a bit before firing …….. stay safe.

Unfortunately I am not a reglazer. I find for cone 6 and 10 it stresses my wares a bunch and really I have very limited success. For low fire stuff, this may be very different though. Occasionally I will lowfire a cone 6 piece to change the look or add accent. I think you want to fire to whatever the glaze matures at or has been fired to and performs best at.

I would only add the suggestion that all ought to be effectively protected by a gfi. Tank heaters without the third prong (ground) cannot really be effectively protected. Same for all devices without the third prong. Water, electricity, possibly lots of folks nearby, firing kilns, red hot wares - best to be as safe as practical.

It all really comes down to energy draw and the ambient temps. Charts can help and knowing your actual energy used really helpful

This may help, most things expand and contract with temperature. How fast and therefore how much they do that, becomes one of their finished properties. Glazes that craze generally grow slower than the clay they are applied to or the clay is growing faster than the glaze does. In effect a fit mismatch hence Min’s clothing example. We really don’t know these rates for clay and glaze until fired to their final form. So testing the clay and glaze combination is often the only way to know they reasonably match. It’s been said that getting a perfect match is extremely unlikely and some day the glaze will craze. Maybe 100-200 years from now - delayed crazing. So crazing or glaze fit is not necessarily a function of cooling something quickly but ………… large temperature swings can help reveal this mismatch. Folks often test from boiling to freezing to try and see how well they fit. So very large swings, much more than your 40 f temperature are often used to see if the delay is on the horizon or as a way to validate a decent fit. Simply testing the combination together is generally the only way to know they fit. In theory high differential testing reinforces that they fit well.

I would agree with all above, including the sheer size of the blower motor on top. This seems very industrial for a simple kiln and my guess is you would need to scrap a lot of what they are doing here to likely be used with atmospheric burners. Just curious if you have power available as well, might be three phase by default.

Since the elements glow, the relay is not likely the culprit. Measure the resistance of your elements and if they have risen by 10% then they need to be replaced. Since Fth occurred at such a low temperature, it’s fairly unlikely to make it to much higher temperatures in an acceptable time frame. If you get high measurements then you can be reasonably confident that is the issue and choose to replace or inform the buyer that it needs element replacement.

I would call Orton - the only F prefix errors I see are on page 13. Assuming this is your manual https://www.ortonceramic.com/autofire-express-products

Yep! It will likely tighten somewhat so a nice 10 hr bisque to 05 / 06 might be just the thing. Time at temperature is important to complete burnout. You might be able to work out a slower turn up schedule so it’s not such a guess each time. So turn up to ten, then maybe 1-2 hours nine / eight …… a cheap pyrometer can help a bunch here. Anyway, a way to slow things down and for bisque a way to try and burn everything out that could cause problems by going slowly. All part of testing and learning kiln, clay, glaze…..

Crazing is a clay and glaze expansion mismatch issue. In general it’s usually related to the match between clay and glaze and probably rarely related to bisque temperatures so I don’t want to confuse two issues here. As far as pinholes, yes effective bisque may help with pinholes. If all the organics are not burned out in the bisque, they can create a pinhole issue as they burnout in the glaze firing. Effective burnout of organics depends upon time AND time at temperature. Most bisque cycles run 10-12 hours to try and ensure all organics are removed. So now I think you know that you can fire slower and when you have reason, modify your turn up schedule as appropriate. Originally I think you felt that it was firing as slow as possible ……. Hopefully now you have a way to go as slow as you find necessary, bisque and glaze.