Bill Kielb

Compacting the rim with a scrap of clay-bag plastic is a trick I learned to give you a dense enough surface at the rim to absorb more glaze. Sometimes a clay is just so rough, with high shrinkage, that the bigger particles still poke out here and there. A judicious use of a bit of silicon carbide shelf, or other fine-grained grinding stone will take off burrs. 

One of the concerns with underglaze is how it reacts to temperature. While I have no favorite brand colors at lowfire temps often can be much more vibrant. Additionally color shifts with various over glazes can be an issue. Just mentioning because paint your pottery generally favor lowfire stuff for energy use and …… bright colors. The only way to know for sure is with testing. A brief search of the web seems to Indicate low firing temperatures for colorobia.
 
 

Just asking - have you tried lowering the melting point by apportioning the boron? It’s pretty typical to get to cone 6 with .15 boron. The relationship has tested fairly predictable to cone 04. The chart below would indicate prox 0.3 boron gets you cone 1. Katz ceramic arts article here https://ceramicartsnetwork.org/docs/default-source/uploadedfiles/wp-content/uploads/2008/10/tf-boroninglazes-0912.pdf as far as satin and matte - Stull matte allows you to dial in level of matte / gloss. Testing for sure ….. still may give you a starting point.
Other thought is take some favorite cone six recipes and increase the boron to 0.3 or so and lower the melting point.

Fired up great and in record time to hit cone 6. 
Yes, clearly I flushed out the electronics gremlins and Heisenbugs. I'm going to say it was the switch, since that was my most clever, daring, and skilled work. That or my wife was correct and I just managed to "turn it off and on again" enough times. 
 
 

One of the concerns with underglaze is how it reacts to temperature. While I have no favorite brand colors at lowfire temps often can be much more vibrant. Additionally color shifts with various over glazes can be an issue. Just mentioning because paint your pottery generally favor lowfire stuff for energy use and …… bright colors. The only way to know for sure is with testing. A brief search of the web seems to Indicate low firing temperatures for colorobia.
 
 

Let me add a caution here. When mixing power vents and a natural draft chimney it needs to be done with good forethought, engineering and or supervision later to ensure it is working as intended. If a combustion appliance is involved, combining powered and natural draft is usually discouraged by most combustion appliance manufactures. Combining ventilation and combustion also presents some real design and operational safety challenges. From a design standpoint under many codes and requirements, these are rarely combined. Again if this is a kiln with a built in exhaust port, Ie Rhodes passive exhaust design, this might be easy to achieve at least as intended by the manufacture.post the make and model of the kiln.

Amaco yes - good results for me. Colorobia no experience. Stroke and Coat as I recall is a glaze that melts fine at 04 as well as cone 5/6. Not really an underglaze though.

It looks to me like the top element (in the diagram, not necessarily in the kiln) is only fed by one of the 120v lines (the upper one in the stylised plug/socket). Although you say that both 120v lines are getting to the controller, is the upper one also getting to the switches and/or elements?
PS
>I have peered closely at that wiring diagram and wished for higher resolution a lot the past few days
For a different kiln, but probably/possibly the same circuit
https://content.invisioncic.com/r278179/monthly_2021_11/AFFD763E-B04E-4A36-A21B-049717307DB1.jpeg.d8d19f63656d62487cfde60f695535d2.jpeg

... asking for coloured felt-tips on the different styles of dashed lines

Does your kiln presently have an exhaust port? If so this is already setup for a passive exhaust system. Post a picturre or tell us the model number.

Typical direct vent setup* draws a tiny stream of kiln atmosphere from the kiln, which is mixed with much more ambient air in the "plenum" - a box/shape that sits tight against the bottom of the kiln, has the exhaust hose connected to it, and vent holes to draw ambient air. Adjustable vents in the plenum, a decided plus, imo.
* Hence, allowance must be made for "make up" air to enter the space, as the fan pulls (and pushes) dozens of cubic feet per minute out of the room! *
In my (limited) experience, direct vent setups get a lot of the fumes, but not all, which may not be a concern for a small kiln...
 
*like the setups marketed by many kiln vendors

I don’t think the low fire firing will change it dimensionally a bunch. Can you repeat it but make a generous gallery so it will fit a wider range of opening?

Thank you very much Bill, I truly appreciate your insights. This is clearing pointing me in the direction to one kiln, the most expensive choice, but in the long run will get me where I need to be. The next challenge is getting it shipped. 
We definitely won’t run out of battery during the firing (if I keep it within specific parameters),  running a boat/home on solar is complex, fridges, freezers, inverters and the rest, so I’m being overly conservative with my needs. My goal is to make both work , which means happy potting. I’m also getting a portable wheel, so my happiness meter is over the top.
Now where am I going to store all of the clay and glaze.

I don’t think the low fire firing will change it dimensionally a bunch. Can you repeat it but make a generous gallery so it will fit a wider range of opening?

my thoughts
Renewing the wiring harness is a great idea. Making your own great too, but high quality crimp and crimp work is key. If you make your own, please buy a decent locking crimper and good quality welded seam crimps, else the premade harnesses likely a best choice. When I rewire, I use #12 and #10 MG (mica glass) rated wire good to 450c all in an overkill fashion so I can identify with make it better.
Low voltage harness
The current low voltage harness likely is ok and should currently experience less than 1/2 amp of load …….. but 18 gauge stranded is plenty sufficient. You should be able to read the side of the existing wire harness to determine what gauge and what temperature it is rated at. Again the crimp work is the important part with respect to longevity and kiln manufactures rarely seem to use high temp insulation on these.
Again I strongly suggest Measuring the resistance at these element circuits ….. at the relay, would definitely be helpful, possibly for knowledge useful by others but now will also give you a real idea of how much over designed you would want to pursue by knowing your current amperage and looking in an open air amoacity of wire table. Lots of tables here is one https://up.codes/s/ampacities-of-single-insulated-conductors-in-free-air
Since you are exploring rewiring general insulation and it’s typical ratings in order of temperature tolerance:
Mg (Mica Glass) - 450c Teflon products - 200c - 250c (fep, etfe, pef,    And others with f in them) Silicone Products 150c-200c  (srg, srk, smrl - silicone motor lead developed for small motors vibration and temperature) All the above though generally is a decent reason to just buy a premade harness that fits perfectly though. Most wiring begins to fail at their connections which overheat, anneal the copper and continue to overheat more as the conductivity decreases. The physics says this will decrease the electric load on the relays, but a harness that overheats also adds heat to an already confined space. The latter being bad for the relays as well so replacing a harness not a bad thing, replacing with a better harness, even better, but does take some diligent work, good crimps and good crimpers to achieve this.
Airflow and cooling helps everything regardless of gauge and insulation, so making sure there are no obstructions or the kiln is not enclosed in an overheated area with no way to get relatively cool air is a no cost best practice for all the electrical components inside. The control box depends heavily on stack effect which means relatively cool room air can freely flow from bottom to top and out of the louvers.

my thoughts
Renewing the wiring harness is a great idea. Making your own great too, but high quality crimp and crimp work is key. If you make your own, please buy a decent locking crimper and good quality welded seam crimps, else the premade harnesses likely a best choice. When I rewire, I use #12 and #10 MG (mica glass) rated wire good to 450c all in an overkill fashion so I can identify with make it better.
Low voltage harness
The current low voltage harness likely is ok and should currently experience less than 1/2 amp of load …….. but 18 gauge stranded is plenty sufficient. You should be able to read the side of the existing wire harness to determine what gauge and what temperature it is rated at. Again the crimp work is the important part with respect to longevity and kiln manufactures rarely seem to use high temp insulation on these.
Again I strongly suggest Measuring the resistance at these element circuits ….. at the relay, would definitely be helpful, possibly for knowledge useful by others but now will also give you a real idea of how much over designed you would want to pursue by knowing your current amperage and looking in an open air amoacity of wire table. Lots of tables here is one https://up.codes/s/ampacities-of-single-insulated-conductors-in-free-air
Since you are exploring rewiring general insulation and it’s typical ratings in order of temperature tolerance:
Mg (Mica Glass) - 450c Teflon products - 200c - 250c (fep, etfe, pef,    And others with f in them) Silicone Products 150c-200c  (srg, srk, smrl - silicone motor lead developed for small motors vibration and temperature) All the above though generally is a decent reason to just buy a premade harness that fits perfectly though. Most wiring begins to fail at their connections which overheat, anneal the copper and continue to overheat more as the conductivity decreases. The physics says this will decrease the electric load on the relays, but a harness that overheats also adds heat to an already confined space. The latter being bad for the relays as well so replacing a harness not a bad thing, replacing with a better harness, even better, but does take some diligent work, good crimps and good crimpers to achieve this.
Airflow and cooling helps everything regardless of gauge and insulation, so making sure there are no obstructions or the kiln is not enclosed in an overheated area with no way to get relatively cool air is a no cost best practice for all the electrical components inside. The control box depends heavily on stack effect which means relatively cool room air can freely flow from bottom to top and out of the louvers.

In many many years, I have never found proof that one can polarize or directionally align reasonably wedged clay. I have not found that to be credible in my experience.

Thanks Bill! I am unfamiliar with (but now learning about) soft bisques.  Yes, I glaze to 2175F, and after a 12 min hold it's around cone 6.
I like your idea of the 1200 tests, but because this work is time-sensitive (and I have a lot of other firings going on), I'm more inclined to just redo the pieces.
As for the rebisque, I am reluctant because it risks cracking the piece, but perhaps it's worth a shot. 
Your third suggestion is appealing. My bisque schedule goes 100f/hr from 1200–1860 so maybe I just insert that into the glaze.
 
Thanks!!

Just a couple thoughts
1200 f is about cone 020 ( likely not very sintered), folks who intentionally carve soft bisque end up around cone 012. 1860f is cone 05 / 06 so you likely would notice a big difference between the products including: look, touch, size, firmness, absorption, tongue test …… from 1220 f - 1860 f lots of things burnout including sulphur, calcium carbonate, etc…  but they don’t burnout necessarily because of peak temperature. It’s rather time at elevated temperatures so bisque firings are generally slower than glaze.
You could bisque something to 1200 and compare You could re-bisque the pieces in question to let’s say cone 06 to be sure You could slow your glaze firing schedule through 1200 - 1860 as sort of a modified once fire schedule. Slow bisque schedules generally go about 180 f from 1000f to 1700 f btw. I do not believe your actual glaze temperature has been referenced yet. What cone do you glaze fire to? Some of the above more or less assumes you glaze to cone 5/6.
Cone 020 is really a China paint type schedule generally designed to just begin softening glaze, I think the bisque would be incredibly soft at this temperature and not very sintered, but easy to test to be sure.

Just a couple thoughts
1200 f is about cone 020 ( likely not very sintered), folks who intentionally carve soft bisque end up around cone 012. 1860f is cone 05 / 06 so you likely would notice a big difference between the products including: look, touch, size, firmness, absorption, tongue test …… from 1220 f - 1860 f lots of things burnout including sulphur, calcium carbonate, etc…  but they don’t burnout necessarily because of peak temperature. It’s rather time at elevated temperatures so bisque firings are generally slower than glaze.
You could bisque something to 1200 and compare You could re-bisque the pieces in question to let’s say cone 06 to be sure You could slow your glaze firing schedule through 1200 - 1860 as sort of a modified once fire schedule. Slow bisque schedules generally go about 180 f from 1000f to 1700 f btw. I do not believe your actual glaze temperature has been referenced yet. What cone do you glaze fire to? Some of the above more or less assumes you glaze to cone 5/6.
Cone 020 is really a China paint type schedule generally designed to just begin softening glaze, I think the bisque would be incredibly soft at this temperature and not very sintered, but easy to test to be sure.

I trim foot rings almost exclusively, but they don't always look the same.  Sometimes I use a foot trimmer thingy like the one Dirty Girls makes.  I still trim inside it.  I cut a line into the clay above the foot as a glaze catcher.  If a piece has a flat bottom that is a sure sign I made the bottom to thin.
I once had an instructor who attempted to push me away from trimming footrings.  He was quite insistent.  I was quite intransigent on the issue.  I won.  It's my work.  Plus the guy sells his pitchers for like $200 a pop - if you're getting $200 a pop you have time to trim a foot ring IF YOU WANT TO.  I certainly don't get $200 (or anything at all) for a piece but I will still trim a foot ring because I WANT TO.
As for the dishwasher thingy, lots of machine made stuff does the same spill-the-icky-dishwater-all-over-the-silverware thing.  If I ever sell a piece, I will be recommending against putting it in the dishwasher.  If you do it anyway, its on you to counteract that.

In many many years, I have never found proof that one can polarize or directionally align reasonably wedged clay. I have not found that to be credible in my experience.

While not the expert I’ll offer this thought and suggestion: Both relays appear to have failed due to overheating resulting in the plastic melting enough so the quick connection tipped to one side. The corresponding moveable contact in the relay on the right appears to show signs of overheating as well.
So why so much heat? Electrical load or inability to cool itself with the updraft in the kiln. It failed quickly so, electrically overloaded or just a defective relay that can not tolerate the load …. Or ….. new relays use a thinner moveable contact? First step tell us the model so we can look at the wiring diagram which should allow us to see how closely the relay is to or above the rated load and rated operating temperature. From they’re easy enough to measure the element resistance right at the relay contacts to verify the elements are as expected with respect to loading. Maybe the last piece in the puzzle would be this relay in spec is rated by horsepower. Converting to amps gets the contacts down to prox. 12 amps. Elements (resistance loads) cause significant heating in the controls and wiring, so it will be interesting just to see just how many amps the elements are and if the newest forms of this relay handle less than previous for a resistive load. Table below
Just adding relay specs below - all appear spot on except for the meaning of 2hp @ …… rating.
 

The clear relays run hot because the box that they're in is shallow. You'll notice on the top that there are 5 louvers. They switched to the black relays at some point, presumably because they were cheaper, and found that they burned out really fast, so they made the box deeper (6 louvers) to provide more air flow, and it made more room for the wire terminals so they didn't have to use right angle terminals with those relays. They recommend still using the clear relays in the 5 louver boxes. The clear ones are rated for high heat areas, and in general they do pretty well.
@Hyn Patty You need a new wiring harness. You've still got the original 20 year old wires connected to the relays, and they are most likely what is causing them to overheat. I see this all the time in Skutt kilns, and new wires solve the problem. Transformers rarely fail, and I don't see how it could cause the relay to fail, but as long as you have one coming, go ahead and replace it and all the wiring in the box at the same time.

I rely on sanding the foot (after glaze firing) to take care of this. I do polish with the wooden part of my tool when trimming, but that alone doesn’t do it. And if a pot warps in drying I’ll slide it around on a wet ware board to flatten the foot, which pretty much ruins that burnished surface. 220 grit to knock the sharp edges off followed by a quick 600 or 800 wet sanding to polish it a bit. It’s not too involved, a brief operation on a pot by pot basis. My feeling is if I can slide the pot on a tablecloth without any snagging it’s done.
 

I have never seen the direction of the wedging to have any effect on my throwing or any of my students' throwing. Once you cone the clay a couple of times during centering, any wedging spiral is gone. IMO she is overthinking the process, or finding something to blame for poor centering technique. I have wedged 'backwards' of the way she's showing for 30 years, and I've never had any issues. Same with my students. Wedge it, make it into a ball, smack it onto the wheelhead, and center it. With good coning technique it doesn't matter which way it was wedged.