Bill Kielb

You just need a few trips to the space station or book some flights on the Virgin Galactic space line.

I think my best guess initially was layers which would seem to lead to color and transparency of the layer. Reduction could bring into play: copper concentration, level of oxidation / reduction, etc….. , not necessarily a direct function of copper reds but their tendency to be very red when fully reduced and often green / grey when re oxidized. I suspect layers of different colored glaze would behave in a subtractive manner and level of transparency would also significantly affect the color viewed. Definitely an interesting piece though.

They are definitely heating, so some power wasted. If there is enough wire, I would cut them back to clean wire and install a new connector. Even though they are discolored, they very likely only consume (or waste) a small amount of energy. They will continue to heat, which causes a higher resistance which cause more heating, so they won’t improve on their own, they will slowly wear out. Again IMO very proactive - new crimps on new clean wire. Super proactive - buy a new harness.

Maybe …………… They almost seem to be layered, so the difference in thickness likely influences the non reduced color. A very cool overlay effect! Interesting also, usually (not always) the interior of things can be reduced more fully because they are in a less turbulent air stream. Pretty cool effect though.

I routinely do both, however easiest to bisque fire the underglaze for the ease of handeling while completing the decoration. I spray most of my glazes so really this poses less of a concern. What I have found, regardless of the application the underglaze and overglaze really need to be tested together. Some combinations shift color, some overglaze has a bit of difficulty melting properly over various colors and makes of underglaze. It does not sound like you have time to test, but it is really the only way in my view to get an expected result. We spent a whole summer testing and finally made our own clear gloss and matte that melted well over various colors, thicknesses and brands so our brush artists could paint, blend, shade in a normal fashion without too much worry.

So going by the nameplate 220/19 = 11.57 ohms and 220 *19 = 4180 watts (which ought to be somewhere on the label of the kiln) ……. so at the new residential voltage of 240v, 240v / 11.57 = 20.74 amps. Circuit breaker Minimum Size for continuous load (kiln) = 1.25 X 20.74= 25.93 amps. Maximum breaker size = 1.5 X 20.74 = 31.1amps. So if we believe the kiln label then 30 amp breaker is fine, (20 amp breaker) would be too small. #8 wire is good, slightly over rated so very good. Now, please confirm your wiring is at least #10, your breaker is 2 pole 30 amps. From there, something burned so could be a loose connection at the plug, or plug to kiln or elsewhere in the kiln at element connections etc…. It’s important to find it. Since you could smell it and the kiln did not reach temperature it seems near for sure that the defect exists and must be diagnosed before you can safely move forward. One easy way to shrink your photos (among many) is to send them by email to yourself. Usually most email programs allow you to reduce the size while attaching or before sending. Photos definitely would help folks here see things more in context.

What comes to mind is light compound and a small polishing wheel. Definitely would test light, and medium compound before going all in.

It can be removed and these finishes do wear away over time. You may be able to scrape away and gently Polish the glaze if damaged. I think it might prove difficult though, but again masking the good surface could protect it from polishing damage. It should have melted a bit into the softened glaze though, so fully restoring might be really tough. Those small solid figures are probably ideal for your crikut though. As shapes get bigger and fit over bigger curves on the vase keeping a tight seal becomes more difficult. Nice piece. The rim and bottom are definitely a possibility for decent masking tape though for the string straight line.

One possibility - is the atmosphere. To maintain reduction, especially copper reds one needs to provide a rich carbon monoxide atmosphere. If sufficient oxygen is allowed, the the piece simply reoxidizes to whatever extent it can. I should add, small a small amount of tin is usually a very important component for copper red glaze recipes and can have a pronounce effect on copper reds. Not sure if there is any in this recipe though. The example picture below contains test tiles mapped at various places throughout the kiln. These mapped tiles along with the pressurization schedule for the kiln often provide a way to ensure future firings are reduced evenly for that kiln with that specific pressurization / atmosphere. Copper red is very sensitive to reoxidizing so often a nice way to test.

Post a picture of the kiln nameplate, what I can find is a kiln that draws 24 amps (if this is truly your kiln) which would require a 30 amp breaker minimum. Kilns need the breaker to be at least 125% of the load, not more than 150%. The wiring, receptacle etc… ought to be sized accordingly. For now, if it smells electrical it very likely is so finding this before operating it again is necessary. Your kiln is old so it was rated at 220v. Todays voltage is 240v, so it is possible it draws even more than the 24 amps which gets you into the next sized breaker at 35 amps and associated rated wiring etc… post pictures of the name plate, cord, receptacle and wire size if you know it. Kilns are a bit specialized in their electrical requirements so better to be safe as practical with a burning electrical smell and non functional kiln. I found a wiring diagram and looked up in an old cress manual. Both point to the need for at least a 30 amp breaker and number 8 wire (rated for more than 30 amps) I did find a website reference for 19 amps, but did not find Cress recommending this.

In North America NEC has always sought to use them in wet locations or potentially wet. Within six feet of a sink, exterior receptacles, receptacles that power wheels (very wet). Having said that you can buy a GFI 2 pole breaker for your kiln. Will it nuisance trip because of the direct contact with the brick and live elements? Probably not, but it only takes a tiny bit of leakage 0.004 -0.006 amps to ensure it is non Lethal. Here we have split phase 240v with 120v for most convenience and appliances. Elsewhere you will often find 240v single phase (1 hot leg and one neutral) so that friendly lamp cord is carrying twice the voltage and maybe a bit more potential for leakage. GFI protection for most of their downstream loads is common and safe practice. Do they run kilns through a GFI, yes they do.

Yes anything is possible, but I have never really found that special slow speed for quartz inversion. Fast conefire programs in the Bartlett controller can be anywhere from 150f to 570f per hour. Slow speeds 100f - 400f per hour. Since thousands of pots go through this daily (often fairly unevenly) I just have never found a credible “slow” speed. On cool down most are subject to whatever speed the kiln goes naturally. I guess if you find a speed that works for you, use it. As far as crystobalite, that’s quite a list of things before one starts thinking about it. I guess in the end, do what works for you but clay is really tough stuff. I suspect quartz inversion and crystobalite likely get blamed for lots of things. One of my instructors would say:”stop blaming the kiln, make better stuff”. In my experience I have found that to be reasonably pertinent.

Generally China paint / lusters go as fast as you can. Truth be told, Cristobalite is just plain hard to have and everything goes through Quartz inversion. Hundreds of thousands of pots each day up and down slow, fast, unevenly. Clay is tough, this is just something that happens. For the most part good clay theory to know but rarely affects typical potters.

Yes, IMO this does work for other gypsum and plaster surfaces. stucco, interior plaster walls, cement …… kill the mold, power wash clean when possible, dry thoroughly and seal as practical to reduce the absorption. Painting interior plaster surfaces has always been the norm to add significant longevity to them. I think it’s a good practical idea. For this: making sure all mold is killed, non destructive cleaning, thorough drying, then painting to preserve the fine detail would be some thoughts that strike me. As always testing thoroughly prior is key to me.

First total guess, I think it’s far more likely the circuit breaker has tripped rather than the sitter switch disconnected without tripping. Either are possible so please cycle the circuit breaker completely off then on. Now, onto diagnosing. Tell us the make, model of the kiln and all the info on the electrical tag mounted on the kiln, then tell us the breaker size etc…

I do not. Not knowing the limits of the materials here …….. there are many mold removers used for plaster, stucco, cement. This is such a precious piece and from what I know of the residence time to kill mold which is significant. We are not even sure it is mold. I think best I can speculate, dry it out thoroughly and have someone recast and make another mold. My heart truly goes out to CharliesMomma and feel I would try and do anything non destructive to reduce the risk of losing this piece or the precision and original character of it. To me — make another mold first before experimenting with chems and scrubbing. Having done that, then yes gentle cleaning and sealing would be something I would cautiously test and try.

Neil pretty much summed it up but I just would add …..extension cords will likely have losses. If the cords warm at all, then that is wattage wasted not getting into the kiln. You are already challenged with not enough heating (watts … =3.41 btu per watt) so any losses here or warming of the cords could matter. Never a good idea to extend kiln power with extension cords btw.

Post a picture of the kiln tag but you are right in saying the newer models are only rated to cone 4 or perhaps derated a bit over the years to cone 4. For kilns that need to get to cone 6 repeatedly you will find folks buy a kiln rated to cone 10. This may sound counter intuitive but really the maximum rating is a number something could get to at its very very best. When electric kilns fire the elements wear a little each time. So a reasonable rule of thumb is a cone 10 rated kiln will usually fire maybe 150 firings at cone 6 before it wears enough to require element replacement to make cone 6 in a reasonable timeframe (prox. 8-12 hours). Clay and glazes depend on a maximum temperature but also a minimum speed of firing or heat work. Really not unlike baking so 350 degrees for 25 minutes to make a great pizza would be considered appropriate but if it took hours just to reach 350 degrees our pizza would likely not be tasty in the end. Post a picture of the kiln tag to confirm , but it likely is more suitable for low fire (cone 04) work or perhaps even built more for glass firing.

I have used it for flat surfaces, I spray my glazes though and when removing I pull back the tape at an angle upon itself so it cuts a clean line. For very sharp lines or complicated shapes, pin stripe masking tape then adjacent area masked with anything. Again spraying this makes for an easy task and proper removal makes for very sharp lines. Just an idea For adjacent alternating stripes, I would likely mask and spray one glaze, remove the mask and paint over the glaze carefully with latex (gonna have to hand paint something), spray the adjacent color glaze infill. Bisque fire the latex off and top the entire vase with a tested suitable companion clear glaze.

The Axner site is still posting the 2011 memo so maybe still part of the 3000 tons they found at the mine. https://www.axner.com/pdf/laguna/Chemical_Composition_of_Gerstley_Borate.pdf

just searching Axner (Laguna purchased them years ago) Here is Gerstley on the Axner site https://www.axner.com/gerstley-borate.aspx looks like you can get it in the mid three dollar range ($3.68) in quantity.Laguna also still has Gerstley in their site catalogue. Addditionally, Epk appears to be $0.52 per pound in quantity.

No worries, his wire size needs to fit the existing kiln. Element loading is partially dependent on element length so the more the merrier I suspect, It’s likely a reason why many kilns are parallel as well as the ability to zone. I think either likely would be a lasting solution. I have no preference to serial or parallel really, just that he gets a workable wattage and it is safe.

Just an add - really agree with everything thus far and your approach as well. Just an FYI - 3.5 watts and above is probably desirable, table below might help with what’s out there commercially. Those that approach 4 watts tend to exhibit significant firing longevity at cone 6. Second add, for series or parallel (within reason) you ought to be able to get heavy gauge wire. When any break happens in a series circuit, the entire kiln stops working, so parallel operation has an advantage in that respect.If you are stuck, Euclids generally can wind them.

Ok, looking at the numbers your current old element calculate to 2215 watts ( presumed well worn) if you can measure everything and just confirm then new these were likely 2500 watts which fits Neil’s comparison well. We are just not sure in the end how well this kiln is insulated so 3000w may still be the reasonable goal for longevity of use at cone 6. Especially if you plan to pack it with lots of wares at some point. From there since it is a retrofit you will need to make sure wiring and fuse size are correct. This type of load that can run for hours is often classified in a special way as it tends to heat up the breaker and fuse. In North America (and many other places) protecting a kiln requires a breaker 125% of the load, or put another way, we are not allowed to load a rated breaker greater than 80% of its rating. Fuses have always been treated the same, so if you are my age you would remember the slow blow fuses for fuses that were too tightly sized. At 3000 watts and 125% that puts this just over 15 amps. So in the end, maybe easier to have Euclids wind you new elements at say 2850 watts giving you plenty of fire power and in reasonable order for your present fusing using typical load protocols for most fuses and wire. If you go for the 3000 watt option then wire and fusing will need to be checked to be in compliance with code. 16 amps actually works for 125% @ 3000 w so not sure what your next available fuse size is from 15 amps. Fuse and wire typically would be sized for the new 125% load. Whatever you do, I suggest when you are done, remark the label of the kiln as to what this thing wattage wise is with something permanent. What would I do? I think I would splurge and upgrade everything to 3000w if possible so I had plenty of fire power and could make cone 6 for lots of firings to come. edit: Just realized you have a 13 amp circuit, all the info below is great -I would suggest size it and the wiring to your current codes and current available products.

I still am Interested in the whole kiln measurement it could give us an idea what condition ALL the connections are in. Having said that, it appears the kiln at 2.5 kw has trouble making cone 6. So, measure both elements, then measure where the power comes in at - for total kiln resistance (No Power applied) to assess just how good all those connections are. My sense is the connections may be removing some available power but in the end the elements were changed to get this to go to cone 6 and even at their current worn state wattage, they are not really able to power effectively anymore. Which leaves you with what wattage works? Sometimes it’s easy to look at similar models and note what wattages are offered to achieve a temperature / cone. My sense is this thing was upgraded to 3000w and now has dropped to 2500 w. due to wear and tear and has trouble making cone 6. I would rule out the bad connections first though, just in case we find out they were decreasing the potential power by a few hundred watts. Finally to know the actual firing wattage measure the amperage if possible, and yes knowing this we can derive the heated resistance.