Bill Kielb
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Posts posted by Bill Kielb
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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.
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3 hours ago, Myceliuman said:
Or any glaze for that matter.
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.
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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.
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4 hours ago, Dabombmom said:
It has me wondering if copper and clay Could have some sort of tie together
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.
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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
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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.
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1 hour ago, Lbauer12 said:
If I reglaze a piece that was fired to 05, should I refire it at 05 or 06? Most of the bowls are 1-2 more coats totally covered.
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.
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59 minutes ago, davidh4976 said:
The heater does a good job of keeping the water in the tub in the 70s.
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.
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It all really comes down to energy draw and the ambient temps. Charts can help and knowing your actual energy used really helpful
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48 minutes ago, Lbauer12 said:
That makes sense thanks. With the 02-06 clay that I have why would I experience crazing if bisquing to 04 then using 06-05 glazes? I guess the elements are 05-6, but are some glazes just not compatible with certain clays even though it says they are?
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.
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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.
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36 minutes ago, Donegal said:
The elements both glow brightly when test fired. I really need to solve this problem since I want to sell this kiln and buy a different model. I suppose I could replace the relay and see if the error goes away. Any advice?
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.
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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
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6 hours ago, Lbauer12 said:
Would it be ok to re-fire it at 10-12 hours?
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…..
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7 hours ago, Lbauer12 said:
Will firing 10-12 hours instead of 5-6 help eliminate pinholes and crazing?
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.
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FTL message usually indicates not enough power to get to temp. Worn element(s), bad relay - some mechanical or electrical reason it cannot maintain a reasonable rate of heating at the end. On the test tile side, Orton says most of the important (flux) heat work work will be done in the last 200-250f degrees given a reasonable rate of rise during this period. If your kiln stops well short of that last 200-250 degrees then generally things can be restarted as if nothing significant happened.
In your case, you are sort of close so restarting likely fine if you can make temp at a reasonable rate. If it stalls again though you are going to need to diagnose the problem and those tiles are likely half baked and depending on the stall temp can end up looking any number of ways. If you have witness cones in place then plus one - you will have an idea of how much heatwork you achieved. If virtually none, then repair the kiln and refine.
My guess is it stalled for a reason and It will stall again. My rule of thumb is if it stops 250f or more before it’s final temp it usually can be cooled and refired after repairs with it likely ending up looking / firing as normal. In effect no heatwork was done during the most important phase.
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15 minutes ago, Lbauer12 said:
Do 04 or go to 03? Which will be more likely to reduce defects?
How about an empty firing to 04 just to see how long it takes to get there with the dial set at 10 and never turning up? Maybe make sure you can make it in ten to twelve hours? It’s just getting to know how your kiln fires so you can apply it as needed.
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56 minutes ago, Lbauer12 said:
so idk how long that would take.
Maybe time to test it out?
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24 minutes ago, Lbauer12 said:
Should I just bisque to 04 and try to extend as much as possible by leaving it on low at the 10:00 position? Should I leave both the peepholes open the whole firing to extend it?
If you leave it on 10 with your normal peep hole procedure, how long does it take to get to 03, or 04?
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3 hours ago, Lbauer12 said:
What’s a firing schedule? I have this set to auto low, turn the infinite switch to about 10:00 let it go 2 hours with peep holes open, turn to 8:00, shut bottom peep, then 6:00 with both closed until it shuts off.
While Fast glazing may / may not be a problem, fast bisque generally not the greatest practice unless you know your clay has burned everything out in that timeframe. To slow things down modify your turn up schedule leave it on low for longer or turn it up less. Duncan provides calibration instructions for the switch. It may be too old to calibrate but following the analysis part should reveal if it is just too worn and needs to be replaced.
For now, just as a test, I would slow down the bisque simply by firing slower, more in the 8-12 hour range for sure to see the effect on your clay and glaze. If you leave it at the 10:00 position and do not turn it up, how long to 04? If that extends the firing, then calibrated or not calibrated you have an option to slow things down to test with.
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On 3/22/2024 at 9:32 AM, Lbauer12 said:
I have a Duncan the teacher manual kiln that fires pretty fast: 5-6 hours for cone 05. I figured the problem was that it was firing too fast, I slowed it down as much as possible
What is your firing schedule?
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On 3/21/2024 at 3:58 PM, Dizzygirl said:
I’ve tried everything to get these set screws out.
One thing comes to mind as possible and non destructive (so to speak) for extremely difficult bolts, etc we used to use an impact driver. Back in the day this was a very manual thing you pound with a hammer. Today cordless drill and driver sets are very common. If a hex key still fits, you could get an impact driver hex key and likely remove it with that. Amazon, harbor freight have some real cheap impact hex keys that fit todays drill / driver and you only need it to last for a couple removals. So if you have an impact driver or can borrow a friends and the hex key still fits, this may be a very good option. If the hex key no longer fits, they make impact driver extractors as well.
If you drill this thing then only drill the center to fit your extractor and not to over-drill and damage the threads. Drilling this completely out probably creates the most work to restoring with a larger set screw and newly threaded hole.
Last piece, lots of study about penetrating oil, many favorites, rarely do they work on their own though. Most still require significant mechanical energy to get the thing moving so don’t get too discouraged. The impact driver just might give you enough mechanical advantage to free this up relatively easily.
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1 hour ago, Dizzygirl said:
’ve tried everything to get these set screws out.
Do they extend out of the hole or are they fully embedded? Maybe post a picture.
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47 minutes ago, davidh4976 said:
I think the "Ceramic Arts Daily publication of 15 tried and true glaze recipes" are all cone 6 recipes
Lots of boron in those recipes Min linked. They look low fire / raku.. tried fergusona white, and two of the copper. Results were fine as I recall.
Purchasing a kiln for home studio use
in Equipment Use and Repair
Posted · Edited by Bill Kielb
In the UK the declared mains voltage has been 230v single phase I believe. North America uses 240v but split between 2 phases ends up at two 120v circuits to neutral. I think it would be odd to have 120v available without your very own step down transformer. Check before buying for sure to be safe. Check a light bulb or two - ought to be rated at 230v in the UK.