Bill Kielb

IMO, switching the neutral provides for the possibility of a higher resistance connection, something beyond zero volts. Most things are surrounded or in proximity to a ground plane of sorts so switching to me adds more risk. The specs are confusing to me, but why he has a three pole relay with an end switch is a bit of a mystery. If he has more than one set of elements, then that relay may be applicable. My assumption is those contacts don’t exceed 25 amps total load though. A few pictures of the wiring to the relay with context included for the connections would likely solve the mystery.

Yep, Stull! He was limited by available fluxes and his claybody at cone 11. The most useful for me is his matte / gloss line and with some indication of how it ought to fire which then prompts further diagnosis such as is this fully melted, etc…. We get the question of how to make a matte glaze here every so often. Slow cooling, magnesium matte are the typical responses and they are fine, but moving something between matte and gloss generally follows Stulls trend which is fairly easy. I have designed visually as well and Stull folks often group. I do like the simple true matte definition though and have observed the over fired runny matte as well as added silica from matte to full gloss. Sue M has some nice in studio testing and research detailing how to get better clarity etc…. Derek Au (Glazy) I believe is trying to gather data for a heat map to apply to the Stull chart. I am partial to Flux ratio as being an initial indicator if a glaze likely can be durable. The Katz research on boron required I find very useful as well. Cullen W Parmelee also interesting work - (Stull Era), lots more for sure not to be forgotten.

Looks like this is rated at 25 amps max and your load is 26 amps and each is rated at 9 amps @ 240 v.. This is also a three phase contactor with an end switch. You service should be single phase 240v, 1 hot wire and one neutral. Not sure this is the right relay for several reasons. Even though resistive circuits start without tremendous inrush, they do generate a lot of heating in the circuit though. It’s regular practice in North America to supply them with wiring and switching that is rated 125% though to minimize the effect of the heating on the switching device such as a circuit breaker. As a control relay, these contacts should be rated well beyond the maximum load for longevity. Since you have single phase 240v (not split phase like in North America) you really only need to switch the hot phase. Picture of how the elements hook to this would help, and the auxiliary contact is rated much less so depending how it’s used, could be an issue as well.

Yes lots of generalities around clay often don’t always hold up in all cases but being extra careful not a bad thing I suppose. Stull drew his map and did his research prox.. 1912 so maybe he indirectly inspired Currie. RT Stull was the head of the ceramics engineering department at the University of Illinois - my home state.

Nice picture(s). 8 gauge type K I believe. If you buy it 6” long then trim leads from the back to match the existing size. The good news is that the weld at the tip appears to be failing which definitely could cause erratic operation. Usually it corrodes away and is very visible see below. Yours looks like the weld is defective. To make a thermocouple the two dissimilar wires need to be reliably connected to each other. Your weld looks cold and twisted so may be intermittent. Still check all connections visibly and with a screw driver - the yellow thermocouple wire. Make sure the bare wire is actually under the screw and it is reasonably tightened FYI - After many firings, when we see the wear bellow we just replace them beforehand knowing they only have a few firings left on them. Picture of a new thermocouple below for reference

You may find this a good watch. https://youtu.be/DptgFBkynHA Sue is one of my favorites and recreated Stull and presented at 2018 NCECA. Her presentation was to simulate Stull in test tile form. To answer your question Si:Al ratio of 4.34:1 ends up to be relative as that glaze needed additional boron to ensure it would melt over heavy underglaze applications which was the specific issue we were trying to solve the summer of 2017. The additional boron does affect the surface. However, that glaze was designed as a true matte, meaning even over-fired it will be a runny matte. Anyway, no method is foolproof but if you use Stull as a reasonable guide to the expected surface it can become a game changer. Predictable surfaces often lead one to inquire and test whether things are under fired for the composition. Anyway, Stull kept his fluxes at 0.3:0.7 for good reason at the time, and fired and mapped the result. Sue emulated that in tiles as Stull becomes another tool in analyzing glazes. Sue does a great job of explaining it IMO and is worth the watch and read. Additionally there have been studies on mattes and durability and there certainly are many true mattes that are durable, so testing IMO is always wise. Funny, everyone wants to slow cool to get the matte look but a matte that develops later is ok and durable? I am not sure why that would be better but believe testing is always wise. Anyway, Stull can be helpful in my view and SI:Al has a pronounced effect on the final expected surface texture. Like anything though, just another tool, have not found the one stop analysis tool, limit formula, experience, etc…. Yet. It is interesting you sort of re-created Stull on your own. Sue has a wonderful site IMO and generally shares her research. Worth the read in my opinion. Her site: https://suemcleodceramics.com/understanding-cone-6-nceca-presentation-2018/

Type K are typical, post a picture of your thermocouple and the information on your equipment tag of the kiln. (Model, voltage, cone, etc…) to be sure. Thermocouples act like a battery and output a very tiny voltage proportional to their temperature so while it does happen, jumping from one reading to another may indicate a loose connection, contact with the metal shell of the kiln as things expand, etc…. The more pictures here (off the thermocouple and connections) the more informed the answers will be.

As you have experienced, there is a wide definition of matte surfaces often qualified as satin or semi matte etc…. Transparency varies as well, so some level of right up until it’s translucent. I think all perspectives are valid though. I have bowls matte on the outside for their aesthetic appeal. Some have gloss liners, some have satin finishes inside. The ones with zircopax often metal mark regardless of the finish. I think testing is the only way to find out if it’s appealing and acceptable and functional to you. I think my point about the recipe is it most likely can be done to fulfill your needs. The recipe I posted is simply one we created when we had similar needs. The real reason for my post is the glaze listed above appears to be is a lowfire or cone 05/04 style glaze. Since you are firing cone 6 it presents a bit of a problem or extra step to getting your clay fully vitrified and in the end may not fit.

It is true about the lids, for a few months for various odd reasons I lost lids to the pots I made. The rest of the topless accounting was a light hearted joke created by members in the studio surmising what could be done with the bottoms. It grew into the topless pottery marketing approach. Just a little fun.

Babs is spot on, post some pictures. Patch A Tatch is a fired solution. Your best solution could likely be an epoxy product protected from UV rays.

This should get you close. Less silica = dryer look, more silica it will go to a full gloss. No guarantees it fits your clay but fits our porcelain, Bmix and some others. And yes it’s relatively transparent. https://glazy.org/recipes/19734 Quite obviously you cannot reduce silica forever nor increase it. Our experience per the recipe posted it’s fairly dry per the existing recipe, fairly transparent and a sample has been in the dishwasher for years now without any signs of degradation. Some folks have posted very positive results on Glazy as well. I may as well add, for interior glaze you can add silica till more satin and generally eliminate metal marking etc… we had folks do this regularly so they could clear glaze the entire pot and maintain the look. I have a progression of it somewhere from very matte to gloss. If I can still find it I will post here. Ok found some of them, not the greatest but they go from a fairly dry matte to a full gloss. If you follow Stull at all, this is a fairly easy thing to work through. Sorry about the order and the Glazy picture is probably truest for the base glaze. Actually the sugar bowl below is probably the best close up example of the recipe posted on Glazy. It’s fair to add I am compelled to add any of the pots or references I post are for educational purposes and often are solely produced by me or in collaboration with my Marcia. The collaborative works can only be attributed to Madison pottery a single entity, but in many collaborations I am the thrower / glazer, Marcia loves the artwork and is truly a gifted artist. We do not sell any of the work, including any technical work I write about where the pottery community is the focus. Even though some of the work is my sole production, most often it is the result of a some form of collaboration over the years. The pot below was thrown by me, decorated by Marcia Grant and glazed using a glaze we worked on together under Madison Pottery. The glaze was subsequently published on Glazy for use in the public domain under Marcia’s Matte.

The samples above remind me of fashion art. Simple line work using pen or brush to capture the essence using gestures etc… If you google fashion artists you may find more samples and more inspiration. Folks who are good at it often capture things using pen and simple gestures very effectively with simplicity. Some fashion Artists here : https://www.fashionillustrationgallery.com/artists Andy Warhol definitely is in this list

How about painting / drawing it to your taste with underglaze.

@Roberta12 As they say, check anywhere lead can be so walls, blinds, surfaces kids can get their mouth on. For me it’s inside lid and sidewalls. 3m instant test instructions here https://multimedia.3m.com/mws/media/815979O/3mtm-leadchecktm-tri-fold-brochure-08-28-2012.pdf

Sorry to hear that, hope you do find some success and get a replacement or two.

Not sure what your elevation is but Northern California has had temperatures near or below freezing lately. It does look like the shelf is delaminating and might have experienced freeze thaw type damage. Just a possibility.

I think I would address it for the context that is presupposed. It is a machine, and as such machines have useable life spans. 10 years is typical. A car is made of steel, steel can last 50 years, yet a cars real lifespan? Bricks last hundreds / thousands. Ancient pottery lots more. The thing is a kiln and like a roof, it has exceeded it’s expected lifespan in an accounting sense (capitalization), in an insurable sense (replacement value), in a warrantee sense, in a safety sense, and in currency of operation. Time for new kilns with digital control and also suggest they not build their next house out of insulating fire brick or fire the house beyond 2000 degrees twice per week or order their next car with a hand crank. Sorry, that brick argument trips my trigger. You can always maintain things and keep them working. It’s a capital improvement they should address regularly as part of their budget. Time for new kilns, especially if they have the funds. Volunteers often contribute time and energy to benefit everyone and keep costs down. Administrators should figure out how to administrate appropriately and run the best program practical rather than tap into the free labor of volunteers to fill gaps in their budget.

Since this is an oval Kiln and likely not very tall its firing area will likely be limited by burner space and draft strategy. Flue / chimney sizes are most influenced by total btu and type of burner(s). Do you have an existing design you are patterning this after? I assume it will remain top loading which will influence placement of the flue a bit. Can you post anything on dimensions, concept, btu ….. it will likely spark more ideas here.

Interesting! Long ago when I first started I made lidded pots only to often find out the lids I made failed miserably. I was left with a plethora of pots with no lids! What to do? I opened my first pottery business …… named it Topless pots! Opening day I was jamb packed with folks lined up down the street. I thought I had found the perfect lasting solution, but In the end lots of disappointed potential customers for some reason. Finally, I had to learn better how to make lids that lasted. Glad that worked for you, hope it is lasting and if not, you have lots of ideas above for speed drying.

This may help and I think this might illustrate Neil’s description above and ensure both legs of the bottom element are disconnected from power when off and sized for the load, it uses the existing relay in the top Left of your diagram. Disconnect all the wires with an “x” On power relay “A” move terminal wire #1 to terminal #4 Run a new 10 gauge high temp wire from relay terminal #9 and connect to L1 Run a new 10 gauge high temp wire from element connection to relay terminal #6 Install new infinite switch and run h2 & h1 to power relay A “coil” this will cycle power relay A and in turn the lower elements per the setting on the new infinite switch Intercept L1 & L2 as shown and connect to new infinite switch. Note since these are normally closed, relay B is just fine as is unpowered except for the coil connections.which should be removed. Note all timers and high, medium, low switch will be entirely disconnected and non functional. Pretty sure that all works, maybe folks here can double check me.

I would definitely make sure there is grog or silica or alumina under this so it can slide easily and freely in all directions. @Pres used a salt shaker I believe which is a perfect representation of how thin and evenly it can be applied. Having said that, the scallops are a perfect place for a crack to originate during construction. So definitely extra care when carving these.

Unfortunately the bottom elements are hooked to a normally closed relay controlled by the repeat cycle timer. Since the relay is normally closed, the repeat cycle timer actually opens this switch turning off the elements. If the repeat cycle timer does not cycle about once per minute, then the elements stay on. I couldn’t agree more with Neil, adding a third infinite switch is probably the best fix I have seen for these. The timers are expensive and mostly extinct and really did not provide clarity in operation nor any real automation to this kiln.

The lead issue is big for me. The story of Thomas Midgley Jr. is an interesting one. Lead contaminates everything! Good story on contaminating the planet - here https://youtu.be/IV3dnLzthDA IMO good you did not buy it.

I would agree with all and add that traditional wadding (50/50) has more than enough silica from the kaolin. I have even tried refractory coatings (ITC). In the end, salt soda eats away at everything. I will say the bonded nitride shelves were better than the old silicon carbide. I don’t believe the nitride were recommended for that use at the time though. I would have to count but that kiln probably had 20-30 ( mostly cone 10 soda with reduction - if ya wanted it) firings on it with regular patch type maintenance. I think with diligence that old Alpine could go 50 - maybe even 75 or more firings actually. All depending how diligent the maintenance of course. Removable reduction mostly saved the O2 probe.

Among many other methods, often if you email them to yourself, you will be asked if you would like to reduce the size prior to sending. The emailed pictures would be the resized originals. Don’t forget to lightly grog your shelf for anything heavy and large so it slides easily.