Bill Kielb

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.

The diagram below may help. Your 2 kw kiln ought to measure: 240^2/2000w = 28.8 ohms. So we dont know if these are series (additive) or parallels which would generally half the measurement but what we can say is if the resistance measured at the cord end (where it plugs into the wall) should be about 28.8 ohms to produce 2000 watts of load. Higher measurement, means wear and less heating watts. So measured in total or at the cord end that plugs into the wall or where power is applied. if you are approx. 10% or more above 28.8 ohms (28.8 + 2.88 = 31.68) then they are worn. Just make sure all measurements are done safely, (no power) and both elements do glow when they are powered. Sounds likely they are worn. You may find formula circle below handy

Just a quick comment, this bonding if convenient may be very suitable for your use. In general though it will always be weaker so trusting a cup handle to it is something I would discourage. From an observed perspective, it’s often said that eventually most glazes will craze because an exact fit is really tough to achieve. By observation, many crazed glazes fail before the base clay fails so likely not the best choice for a connection that can go into tension. For sculptural use, maybe just fine though. If there is a risk of failure you could always bond this way (glaze) and reinforce later with clear epoxy that has significant fill and tensile strength. In the end it is a bonded joint and at greater risk than a mechanical joint. So in the end if it’s 10 pounds and will hang from the ceiling ……..

My experience, very hard material and brittle, especially if its use ends up to fill gaps in the mating parts. Attaching clay to clay has always seemed most durable to me and post fired, structural epoxy has been my go to. Having said that, feet that remain in compression, things of that sort seem fine with glaze attachment. Things that can experience a moment (torque) such as cup handles can be unreliable or at least fail unpredictably.

@Roberta12 - I have not, standard art brushes that you prefer to paint with probably. filberts, flats, liner, limited use of mops, daggers, etc.. Typically synthetic - nothing special really. More about what you would use to paint. Donna Dewberry brushes were cheap at one point. Paul Lexington has a decent book: “ China paint and Overglaze” finding the right medium to match your preference probably most time consuming. Clove and lavender! Stuff seems to seep under stencils due to adhesion and cohesion. The pin stripe masking tape is an easy way to stop this movement for me.

My experience, it’s hard to keep it from flowing under the stencil so depending on size and shape this may prove to have its issues. Precise brushwork is a thing with multiple coats over the top. Real automotive pinstripe masking tape does allow for very precise lines, especially1/8” and will keep the media from flowing beyond its boundary. Gold needs to be fairly thick (else fires ugly) so often multiple coats are the answer for me which often means more freehand work. If it’s tape masked, then no worries for me.

seems like you likely have proven you have a defective pedal. Speedball used to carry a 100% 2 year warranty for parts and labor so I would call them. Definitely visually check the pedal operates mechanically freely and there is no clay or other debris hindering its operation first though.

This post is pretty old so you may want to direct message them. .33mm is about 13 thousandths, I think for that you could loosen them in the holes and move them slightly before tightening them. If not perfect I think you can get them in the single digit thousandths. You might want to loosen, put your best batt on top, center it perfectly as possible and tighten them up. Assuming the accuracy of the measurements, I think it likely could be centered within a few thousandths of an inch. This should not affect throwing though, very few batts are cur this precisely.

Yep, 0.3 bar IS 300 mb so your kiln ought to have orifices sized for this higher pressure which means they will be much smaller than Chloe’s kiln marked as 31 Mb (see below) So assuming someone has not changed the orifices you will need a regulator to drop tank pressure down to 0-300 Mb. About ten times more than Chloe. Max pressure does not necessarily mean operating pressure though. So I would suggest double check the current orifice size, confirm the operating valves are rated to at least 300 mb just to be sure this will operate safely on 0-300 mbar. Raw tank pressure can be more than 10 bar or 10,000 mbar so proper regulation is important. Chloe’s tag below for reference

@Nick C-S I believe that thread was from 2022, you might want to direct message Cloe (The little envelope at the top right of the page). As far as the pressures you mention, 31 mbar (Her kiln label I think was actually 31 mbar in the label) would be low pressure and require a first AND second stage regulator. 300 mbar is ten times more pressure and requires a first stage only regulator. If your kiln is rated at 300 mbar, it will not run correctly at 31 mbar. To confirm post a picture of the label on the kiln, the pressure and orifice size should match an orifice table at medium pressure for the gas being used. Confirm 300 mbar is correct before operating it at that pressure, it’s not typical. Most gas kilns need proper damper and gas management so all the heat does not simply go up the flue.

Which controller do you have, the ramp soak - high limit, proportional or full blown atmospheric? Post a picture if you can. Shutting down at 1900 degrees indicates a safety of sorts. Either high limit or your pilot sensing dropped out. Since this happened twice at 1900 degrees it points to high limit, post your program. Uneven reduction points to air leaking in which usually indicates the management of the atmosphere and the pressure in the kiln. Which can be damper operation, change in kiln power: gas pressure, burners, excess leakage, restricted flue….. Natural gas should be very clean, (properly dirt trapped) and screens built into the the gas valve ought to catch any real small stuff. Cleaning orifices is fine, usually a spider web / dust. Normal recommendation would be NOT TO enlarge them even by a few thousandths so most often you will see a toothpick or soft copper wire suggested. Also ……… blow them out opposite of the gas flow. You need to remove the orifice to do this so the dirt is not blown back into the pipe only to return later stuck in the orifice. If you have restricted orifices it’s usually obvious comparing one burner flame to the others, especially natural gas. Very blue flames are achievable. Not so much with propane. BTW: it is common for gas kilns to be FULLY supervised throughout the firing. Set it and forget it more of an electric kiln thing. For gas check on it every 15 to 30 minutes seems to be the compromise to100% supervision.

It may work for you. I have a hard enough time when using cones for each firing though so you might be at a disadvantage.. Hopefully your trend holds up.

No just curious to all the reference to peak temp without a rate. So looking at the samples, not really sure what cone they were fired to. The rate on the Orton chart is for the last 100c, but not knowing top temp, it’s hard to pick the last 100c. Complicating things further is many kilns struggle at rate in the last 100c so monitoring it is probably a necessity to know what it actually was. The three rates in Orton are 15, 60, 150 with less kilns being able to achieve 150c per hour in the last 100c. Finally if anyone has been firing as elements wear, firing cone 04 at 15c per hour usually has an effect on the glaze versus say 60c per hour (the center column) So all just very curious how to control this and relate meaningfully to peak temperature. Which brings to mind, the potential variations in fired appearance at a temperature without cones. Without rate, we may not really know what cone things were fired to. And in the case of really slow rates, many glazes change appearance even though their equivalent cone can be found in Orton. As things slow down too much, many glazes just don’t like it. Color and texture often become unacceptable. Just a final thought, I have seen low silica and alumina (Bristol or zinc based) glazes melt very early but also have wild color shifts from blue / violet to golden brown and semigloss to flat matte with 1/2 cone firing difference.

So ……. When you validate cone 04 peak temp you fire at a particular rate then verify peak when the cone bends? Is there a standard firing rate? Just curious.

Do you fire with cones?

The third wire in your cord will be a ground. In your electric panel there will be a ground bus that connects to an earth ground. Florida has lots of plastic pipe which is non conductive so your water heater contains a green ground wire bonded (Mechanically fastened) to the metal parts of the water heater shell for safety. This green wire runs back to your service panel annd connects to the ground bus in the panel. All this connection stuff should be common knowledge for most electricians. The green wire needs to run from your kiln and be bonded inside your electric panel to the ground bus. In the case of a residential service it is very common to require that the neutral must be bonded to ground in this panel only. This often leads folks to conclude the neutral and ground are the same. They are not. In reality, a neutral depends on utility connections so a real earth ground is installed (often ground Rod) and bonded to the neutral in the service panel in the event the utility neutral connection fails. your kiln needs its ground connected to the ground bus in your service panel

Acrylic works, but I would not discount epoxy as well. Very durable paint.

Generally to raise firing cone one would increase alumina and also silica to try and maintain the surface texture.This recipe has few components so EPK is likely a place to start. I am unsure that will solve your colorant issue though. Changing fluxes could be a solution but also may cause more complication for sure so the neph sy idea might not be the direction you want to begin testing as neph Sy has some of the lowest silica and alumina content for natural materials. Things fire by cone, so best to figure out what cone it fires to, peak temperature is not generally effective or indicative enough for fluxed reactions.

I try not to trim much and just throw nearly finished. (Lazy, but good practice throwing) I stopped excessively burnishing especially if rewetting with a sponge. Definitely have caused cracking issues with excessive wetting and burnishing. The bottoms are trimmed very smooth and only very lightly burnished. After firing they all take a few turns on a diamond grinding disk anyway so butter smooth. I do glaze inside the foot though so another reason burnishing is not really important to me.

We have found frost to be a bit picky so we teach what we consider effective compression or for bottoms of cups / mugs …….. some pattern of ribbing from the outside perimeter to the very center as in the video. Folks simply pushing down hard definitely stand a chance of the clay growing outward or less compressed on the whole. For Frost though, I spend a lot more time on handle joins after having knocked several off after a bisque run just to see how well they were attached. If when fractured, the parent material broke off with the join, I considered that well made. If the join simply broke at the slipped connection, then I considered it an ok but weaker than the parent material join and for Frost subject to hairline cracks. (Sort of a welders view of good and average joins) For frost I definitely make sure to compress as properly as practical and for handle joins - compress and often infill to be sure it’s all similar strength and density. Overall, I rarely use a sponge or overwork even greenware with a rib and sponge while trimming as well as burnish things perfectly. I find overworking can lead to delaminating and really strange surface cracks (maybe more like you describe) presumably due to local shrinkage and density differences of areas I overworked. Having said all that I think it has made me better. I still like frost, and the extra attention really does not seem to slow me down a bunch.

Not a whole bunch can go wrong with these - had one for probably ten years. The controller is unique,I believe. Your manual here https://www.speedballart.com/wp-content/uploads/2017/12/Artista-Final-Updated-November-2017.pdf. Only thing I can think of aside from the controller is if the plug in for the foot pedal jack has become distorted or the contacts inside dirty. Maybe unplug and replug the foot pedal several times just to exercise the internal jack contacts to see if the speed knob will work on its own. If yes, dirty contacts and an issue with the foot pedal.

Yes, I am sure it is fine, created for motor leads and medical equipment. Just kidding, in all seriousness I would pick the highest temp you can get. it’s produced in a range of temperatures. My point really was, maybe before spending money for new, make sure this kiln will perform for his use, especially at cone 6. The wire probably will not increase performance significantly unless he has a bunch of annealed and corroded wire right now.

@Skydve76 Just a suggestion reading further through this If this is mainly currently to test operation and you intend to fire cone 6 clays and glazes I think I would clean up the wire you currently have. Just clean the connections, cut back to clean wire and makeup new. Unless the wire is excessively burnt or discolored throughout the length of the wire. SMRL (Silicon Motor Lead Wire) is likely not near as high temp as the furnace kiln wire you presently have in there. For trial sake this kiln may have a difficult time reaching cone six repeatedly anyway. Just reading Dicks thread it likely is underpowered. New wire connecting to element pigtails will definitely get hotter than 200C so buying new lesser rated wire before confirming it will do what you want might be a bit of waste of money at this point. I would also suggest figuring out which temp range clay and glazes you prefer to work with. Many work at cone 6 because they prefer vitrified (low absorbent) properties. Still there are those that work at cone 04 (Low fire) Cone 6 = 2232 f (1222 C) Cone 04 = 1945 f (1063 C) As can be seen both firing temps are well above 200C, which means a lot of cooling by airflow and connection choice to keep this near its specification. If the old wire looks good cut back an inch or two I would do that first till you can sort out the rest.

Picture of where this is coming out of would be great, most (not all) pilots have a fixed opening fo primary air. More important, Do you have a two stage regulator on it (sold separately) this kiln appears specified for 11” of water column (0.4 PSI or less than 1/2 PSI). Your propane tank is about 200 psi on a hot day.

When I am trying to match older designs I use “MG” wire or Mica Glass jacket. It is rated to 450 C (High temperature) and the wire itself to 750 C. Google your local suppliers for MG wire. https://www.awcwire.com/high-temperature-wire/mg-wire An alternative for newer machines has been silicone jacketed wire generally from 80 C - 250 C (Medium temperature) as newer machines often isolate the wiring from the kiln heat source better in a wiring plane using metal to block the line of sight IR from the kiln. Just a reminder - check the gauge to carry the proper amperage.