Bill Kielb

I am not a hold person as to me it simply adds heatwork. In a practical sense there are folks who fire one cone lower but add a hold to get to the next cone heatwork without the peak temperature. In that case firing to cone five with a fifteen to twenty minute hold often gets one to cone six. (Usually verified with cones) Why do that? Some glazes do not like higher peak temperatures. Some underglazes change color significantly with peak temperature. It is a pretty functional way to fire a cone to two cones max higher without hitting the actual peak temperature. Firing higher or for longer has never healed pinholes for me, often made them worse. Drop some temperature and hold however has helped on s some of my pinhole situations. whatever works for you and your desired glaze results is likely the best answer. Whatever is done, I strongly suggest always nice to have cones in place so you genuinely know how much heatwork was done. As to suggested time, 15-20 minutes generally gets you to the next cone.

Not to worry, folks have made glazes forever and experimented looking for predictable ways to characterize what happens. They publish their findings or research and you get to decide if it is useful to you. Commercial glazes have the issue of - what is in them and how does one correct a defect such as crazing. The good part is commercial glazes don’t use lead anymore (for the most part), vanadium pentoxide etc… generally because someone found out it was a bad thing. If you mix your own then you know what is in it and can reasonably test for durability, fit, etc…. to your satisfaction, before selling it or giving it as a present for human consumption. I think it does help to inform but definitely not for everyone.

Sorry the reason I mentioned the firing to cone 6 making a cone 04 glaze less durable because it was a good example that durability and boron were not tested or at least meaningfully tested and meaningfully quantified. I also mentioned it because many 04 glazes will fire just fine to cone 6 - Stroke and coat and look alike glazes seem to fall in this category. The only point was, while excess boron is certainly a thing, we generally should not conclude the current research predicts durability, hence the example that using it to predict an 04 glaze durability fired higher seems to be at odds using it to strictly predict durability. I do not think that was the focus of the 2012 research. Instead we were given a reasonable amount of research that indicated flux ratio’s outside a reasonable range could indicate a lack of durability. Why design your glazes there? Maybe test durability of those glazes approaching less reasonable ratios with a heightened awareness of the potential to be less durable. The gloss test is a doable one and relatively repeatable (if you have a decent gloss meter and maintain uniform measurement protocols) but it is dimensionless really so as a practical indicator and even trend indicator, likely fine. It is dimensionless so maybe no direct predictable correlation to longevity of service. I think the flux ratio research has shown merit and potential to be reasonably useful as qualified above but Boron and durability has not necessarily been tested and quantified. So I believe appropriate to say, why waste the material it’s not necessary to use that much. I do not believe what was written in 2012 was intended as a durability study on Boron in glazes……… just an indication of where did they appear best to melt.

Fire in the kiln? Could be a bit of smoke.

Gas fired appliances need ventilation, the simplest form would be a properly sized natural draft hood. Natural draft hoods are one of the simplest designs because they are simply a hood above the appliance with some space available for dilution air (room air) to also rise up the flue pipe. This open space on older natural draft appliances (boilers, water heaters …) was often called the draft diverter. Quite often before the flue could warm sufficiently this space would allow the cold downward draft to be diverted so as not to blow the pilot out in the off cycle. What COULD it be? Common would be a properly designed flue for the kiln not allowing the cold backdraft at startup. You mentioned HVAC issues, well gas appliances need their own source or combustion air as well sized for the appliance and positionally sized in one of several very specific ways to combat stack effect, dilution air requirements etc… Further: exhaust HVAC appliances need makeup air. Proper design and accounting is important so as not to defeat any natural draft appliances. Does the studio have a paint spray booth or other exhaust appliance affecting this? What could this be? It’s simple stuff but takes real design experience and the potential to be a real health safety issue with carbon monoxide or just a nuisance issue like pilots blown out exists. My experience often these are designed by folks not skilled enough to do so or a failure to follow the manufactures design requirements. Hidden issues like other exhaust appliances with makeup air issues are common as well. If folks are silent or secretive about it, maybe they are not skilled enough to understand all the potential design issues. It’s fairly straightforward but truly requires combustion air zone training in addition to flue design skills. I can’t tell you how many times I have seen direct vents installed for natural draft. My best thought here is find an HVAC contractor with these skills and the ability to understand and follow code requirements. The solution is generally easy, just not necessarily intuitive and unfortunately found more in older techs than younger as these appliances disappear from use in favor of sealed combustion higher efficiency stuff. zI could be several things unfortunately, I included a simplified drawing of some of the interactions of these required airflows you may find of interest in this thread https://community.ceramicartsdaily.org/topic/39240-skutt-envirovent-still-allows-fumes/?do=findComment&comment=251190

I would test, should be fine with the silica but I think I would default to alumina for more worry free separation. Watch everyone else’s wares though, easy to get this on other folks finished work. Folks often add Alumina to their wax for more control of the application however burning out large quantities of wax requires big ventilation so the alumina wax is a nice solution for keeping lids from sticking but probably not so much for separating sheets

Not arguing actually Whether in his class or reading that paper 14 of the 16 pages were devoted to flux ratio. I just don’t think his primary focus was testing durability and boron levels. The one graph we have in the paper shows reasonable minimal gloss degradation from about 0.15 to 0.2@ cone 6. The low point at 0.15 out to let’s say 0.2 With confidence. His demonstration that durability and temperature independence of flux ratios however was a notable central finding which likely gives greater confidence flux ratios can be a leading indicator of durability. Can there be excess boron - certainly, yes. If I take the original recipe at 0.63 boron and simply apply Katz’ boron melt chart and fire to cone 04 it becomes durable? This research to me was not to establish that. It might just be my reading of 14 of the 16 pages though.

I would agree, the more the merrier. Gloss meter readings were an interesting indicator and something easy to replicate. Not really indexed to a quantifiable amount of degradation though. Still it likely is indicative. Stull correlated silica and alumina to a fixed flux ratio, but yes in clay there are an infinite number of fired combinations to which research could be applied.

Yes, he found an ideal boron level at cone 6 but really read through the beginning part of your citation, first several pages all refer to flux ratio, graphs are about flux ratio and his examples provided within the course are about flux ratio . If you took the course and have the notes lookup a glaze he termed Gel-o where he said “ At this point, I don’t see a reason to take functional glazes past 0.35 R2O : O.65 RO”. I feel If you are dismissing the flux ratio as being a significant primary part.of that research you are missing a significant important point. The boron research was centered on how much to melt at what cone. He concludes with a broader range for cone six, but again the ideal flux ratio is first and foremost.

The Laguna info on that glaze says it is a cone 5 matte recipe, also available in a gloss version.

Katz’ research with boron was about melting point. His research about durability was: is there a reasonable flux ratio and being outside this ratio ….. likely non durable. Boron glass / glazes can be very robust and properly formulated low fire cone 04 glazes have tested very durable. The published chart was for melting point and not necessarily durability. Article here: https://ceramicartsnetwork.org/docs/default-source/uploadedfiles/wp-content/uploads/2008/10/tf-boroninglazes-0912.pdf The first part of the presentation cited is about flux ratio and implied durability. “The graph on this page shows the amount of boron required at any temperature. The purple-blue areas are underfired, while the red/ orange areas are very glossy. The vertical axis is temperature in celsius and the horizontal axis is UMF boron additions to a standard glaze. By finding the desired temperature and determining the position on the oblique line, you can figure out the corresponding required UMF boron level at that temperature. This chart applies from cone 06 to cone 10. As a general rule, we define the required amount of boron as an additional 0.1 mole (via UMF) of boron for every 50°C below cone 10 (1305°C). Boron is an exceptionally good material for adding to glazes as it makes glasses at lower temperatures that are just as strong and resistant to wear and chemical leaching as the best cone 10 glazes.”

Can they have an unglazed bottom or foot ring to allow for display? If not, how about casting a sacrificial ring or tab (maybe 3/16” diameter eyelet) into the bottom, suspend while firing, grind off after finished and finish the remaining dot with paint, or a bigger dot and insert logo? Just thinking …….

I think that might make sense. I think I was assuming the relay was not making any activation noise or a click could not be heard. If the solid state relay is not functioning then your elements would not heat up even with the relay functioning. Hopefully they can recalibrate your controller and update any software patches as well. Sounds like you will finally have this solved.

Since this all started with the Tap screen recalibration, it seems likely that it is the issues solve first. The tap executes a calibration routine after holding your finger in one place for 15 seconds I believe. Software updates may effect this as well so probably good to be in a position to get this connected to the net if not already connected. Not being able to start this kiln by controller is definitely an issue before checking other parts.

Good practice. Worn connections usually will reduce power in the kiln and not necessarily make your breaker trip. Definitely fix the connections though - see this fairly often as well. Pictures of main power to kiln and a decent repair below just as an fyi.

Yes, can you manually operate it with your finger. Push the plunger down until you hear a click. If you hear a distinct click then hold this down and see if your inside relay will fire with this held down. If that all works you need to physically see what needs to be done for the lid to engage this switch when the lid is closed so that the switch is depressed enough so that same click is heard. This is a roller safety switch which I believe Is non adjustable so whatever depresses this is often the adjustable portion. If this all works then great, to troubleshoot further is not hard but will take a bit more writing space. BTW can you confirm the 3 amp glass fuse is fine? Very fine wire so you likely need a meter to check it has continuity. If you have power to your controller some way, then that fuse is fine.

Hmm, has happened but usually shows a decent amount of heating. If you can measure the amperage and it truly in the 45 amp range, I think it’s realistic to replace that breaker for tripping early. The typical overloaded breaker I see on occasion below, which at prox 130f definitely made it early trip and definitely feels hot to the touch.. That yours is not heating is interesting but I think reasonable to replace if you confirm your kiln is drawing approximate 45 amps when measured. The breaker pictured below was not sized correctly (125% minimum) and is not old but it is loaded near 100% of its rating.

Check this after several hours or at least four to five hours of operation. Compare with others for perspective

Just curious after several hours of operation is the breaker cool, warm or hot to the touch compared to the other breakers in the panel?

Yep, turns the relays on and off. Everything gets wired as full power and rhe elements just sequence on and off as needed to climb on schedule.

Any reason you preheat this for so long? Is this your normal practice?

Only time I have seen unique circular and spiral failures were from the trimming and burnishing at the green stage, which in those cases very excessive. Was hoping your picture would reveal the actual crack / blowout. Sorry, that’s all I have at the moment. Anything special to add about the throwing trimming process? “Pictures definitely key here as I have seen circular failures and delaminating especially in bowls where the interiors were overworked in the green stage. Pictures and a little about any special throwing, trimming, ribbing, burnishing etc…. could help narrow this down.”

This may help - I like those as well but their mass is small so I personally have seen them fail on the highest loaded elements in the least cooled ares. They are not big enough or have enough surface area to keep the connection cool for the amount of cooling air passing them. Improving the cooling airflow can help if the convective flow from bottom to top can be improved. Reducing leaks out of the kiln by stuffing with high temp insulation can help for radiant and convective losses as well. The simplest solution has been to extend the element pigtail more and position for best convective cooling, just to get some additional cooling to the connection. conductivity plays a role so copper best, brass next, followed by steel / stainless. An old easy connector to build is drill a brass bolt, use the bolt and two washers. Sandwich the wires between the washers through the drilled hole. Increased convective cooling (heat sink) easy to achieve this way, thermal conductivity less of an issue but surface area as well as mass very important. So this can be done with steel and stainless, just harder to fabricate and not thermally as conductive. 1/4” - 3/8” X an inch or two (Cooling surface area and mass) simple brass bolt and nut depending on the clearance in your cabinet can last forever and be very economical and easy to build.

Really nice! If I could give two thumbs up I would. It would not take much conductivity to leak 5 milliamperes.

@SolidCitizen Vented used to mean propped, perhaps with a peep hole or two out. Some kilns came with a small L shaped prop build into the lid, for others folks would prop the lid and inch or so with kiln furniture to vent. Usually in the first portion of the firing to let out any minor amount of water (steam) being released. If this is on a 2 pole GFCI breaker and the breaker trips then there is leakage at that level. (About .005 amps directly to ground) some GFCI breakers are sensitive and will nuisance trip so changing to a new 2 pole GFCI may work. If this run is out to a garage, the quality of the wire, connections etc… can contribute to the sensitivity. Any junction that is wet or moist can cause minor leakage. In my view, if it is tripping then there is leakage so solving that issue can be difficult. Lots of folks don’t run kilns on GFCI’s, just items within reach of water sources ….. sinks mostly. A well grounded kiln is important though so ensuring a good ground all the way back to the panel AND to a grounding source such as water main and driven ground rod is a must to protect from shock. Here is a link to the old generic Paragon manual https://paragonweb.com/wp-content/uploads/IM104-Paragon-Ceramic-Kilns-April20181.pdf venting is explained among other things. 4 way rotary switch operation explained here https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/IM-55-Current-Flow-thru-4-way-Switch.pdf A&B service manual https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/IM5-A-and-B-Paragon-Inst-Man-Jan2017.pdf Your kiln by manufacture requires a 30 amp breaker, btw page 6 guide above. Finally the pilot is likely 240 volt rated neon light. Double check the voltage stamped on the side and replace with proper voltage rated lamp.