Bill Kielb

Generally if a known glossy glaze fires very matte, it is usually under fired. Clays and glazes melt by cone or heatwork and not necessarily peak temperature. Different places in the same kiln can fire to a different cone. So my best guess, underfired.

There are so many articles available on this subject: OSHA, CDC, NIOSH, your public health and government sites. All can provide good guidance so you should read for your state for sure at a minimum. HEPA filtration is the only recognized filter that I know approved for effective removal especially in air filters and vacuums. Minimizing generation is super important so house keeping, wet not dry methods etc….. are most important. Personal protective equipment such as N95 rated masks or other rated masks are also a common recommendation when sanding, glaze prep, etc…. I would start with google and your local health department. Avoiding generating dust is usually a very good first practice which consists of: don’t generate it indoors, so wet cleanup, hepa vacuum, etc… are common. Some things you may see with clay and most clay studios Vacuum your kiln after firing : use a real hepa rated vacuum. Air filter: hepa rated Mix glazes: do this outdoors with N95 mask or superior for personal protection or in an approved paint spray booth, or with approved exhaust. Cleanup: wet cleanup only, no brooms or brushes etc… Read through the documents, much has been written with most requirements unified under OSHA for employers / Employees in the US and uniform exposure standards through federal and state health standards. Your local health department should have plenty of information available right on their website. All else fails, NIOSH has publicized suggestions as well for construction practices and personal filtration and protection. You may find them useful. Your source of silica are basically clays and glazes whereas construction activities pertain to cementitious mixing, grinding etc….. https://www.cdc.gov/niosh/docs/96-112/default.html#:~:text=Use vacuums with high-efficiency,being released in the air.. Your state health department likely has written materials that may be easier to read through, the NIOSH is just one of many. It does not matter which source ……….. how to minimize, how to protect and how to collect are the relevant issues.

Show us a picture of where these are attached inside the kiln presently with a bit of an overview of the wiring (picture) but yes, that sounds correct.

Post a picture. North America is one of the few places that use split phase so The neutral is not used in a three wire load. Just two legs and a Ground. The ground Carries no load, just a safety usually bonded to the shell of the kiln. This kiln appears to be built in the UK which likely means a single phase 240v circuit. A neutral and one hot leg @ 240 v.plus a ground. Here, since we split our phases in residential it will just be two hot legs and of course the ground.

The six foot rule is in place for several reasons but one of is that it becomes a reasonable approved means of disconnect within six feet of the appliance.

I have only heard of local rules affecting the wiring of stoves so as to include a full rated neutral in all installations. With respect to three wire loads, I am not aware of making neutrals mandatory. There are very specific requirements to grounding and bonding to avoid voltage / currents appearing where they should not. With respect to cable ratings, buy the appropriate one for the appliance, there are too many nuanced and tested criteria that really impossible to know with respect to something being “stronger”. My suggestion: If you have a three wire system, do NOT wire the neutral, wire as the manufacture specified

@AJP I think you have it basically worked out with one observation. Propane tanks carry very high pressure to let’s say 200 psi. The point I need to make is you should have a first stage regulator to go from tank pressure down to 2-10 psi. If it were me I would buy a first stage regulator with the tank fitting, then hose capable to carry the 2-10 Psi to your second stage regulator mounted at the kiln and set for 11 inches of pressure max.. The built in valve and gauge on your kiln will then allow you to easily adjust while firing. A hose carrying up to 10 psi can be quite small and carry much more than 120000 btu for more than 20 feet without much pressure drop. It can be easily picked from a table but 3/8” inside diameter is very common and really likely only need to run it in the 2-5 psi range for that small load. Start setting first stage at 2 psi and make sure you can get 11”” at the kiln and you are good to go. The second stage regulator must be 10 psi regulated down to 11” and rated for 30-70% more than the load or 120,000 btu. So let’s say a low pressure regulator 11-14” rated in the range of approximately 120,000 - 200,000 btu would be fine. Too large is not better, it won’t regulate as well. The flexible hose is fine, make sure its rating exceeds 10 psi. Run it as low as you practically can, likely 2 psi or less (the lower the safer) and make sure your second stage regulator is rated at least for your maximum load of 120,000 btu but not so much over rated that it has to make tiny movements to regulate. Remember at 11” on this kiln it’s full blast, so likely you will never really operate it there. Your operation is likely to be in the 0-6” range so you likely will never use the full 120,000. Proper damper management is always critical in any gas kiln btw. After use, shut off the tank valve, before use, make sure there are no leaks. A bit about regulators First stage regulators. These high pressure regulators adjust for any differences in tank pressure. Technicians install them directly onto a tank, and then the regulator decreases the pressure between that tank and its service line. The purpose of this is to provide inlet pressure of approximately 5 to 10 PSIG to the second stage regulator downstream. This allows smaller diameter service lines to easily supply enough btu’s for the appliance(s). Second stage regulators. To adjust pressures between the service line and the appliance, technicians install these regulators outside a building, in your case at your kiln. The low pressure regulators moderate the delivery pressure from the first stage regulator and generate outlet pressure that then flows through to power an appliance. The goal for this equipment is to continue decreasing the pressure in the system to reach safe and appropriate levels for the application, usually an equivalent pressure of about 11″ w.c. Hope that all makes sense. A small diameter connection at the beginning of the high pressure hose is a local restriction and will not have much effect on output so you should be able to connect your hose to the first stage regulator with whatever diameter adapter is necessary. Typical would be 5/8” on the regulator and you will reduce to 3/8” hose. But just be sure you make this connection with the appropriate fitting for each and it is leak free. First stage regulators are pretty available and often come with hose and QCC tank fitting. Just referencing your previous post, any ball valve will work, so big box rated for 50-120 psi is just fine. Connect the end of the flex line to your low pressure regulator. aJust a late add, I picked a maxitrol second stage regulator that should work, along with your pilot safety in the picture. You should be able to google the model # for a supplier. You are looking for the 325-5 series I believe.

Yes of course. Can you sketch or describe the kiln location in relation to the propane bottle or even post a picture then we likely can come up with a solution that takes least specialized parts. Sort of a hardware or farm and fleet solution if you will. Then it’s your choice if you want fancy quick disconnects etc…

If I have your wiring diagram right, and you can hear the repeat cycle timer clicking …. The timer relay on the left I believe, likely good news with respect to replacing the timer. Please check the black relay in the center of the kiln that connects to the bottom elements. If it does not cycle on and off with the timer relay then this relay is bad. If it cycles but the elements just stay powered, it is likely fused inside. If you need to replace this, the coil is rated for 240v operation. It is not your typical relay that you would see in most of todays kilns, so careful with replacement and order a proper relay. your diagram should be https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/W-EA-and-DA-820-2-41.pdf

If you search the forum you will find lots about this generation of kilns. Firing too quickly is a common issue when one or both solid state timers stop functioning as intended. The end result is generally firing too fast. Unfortunately replacement of the solid state relays is often the fix but they are expensive if available at all. The fix is generally to install a second infinite switch and remove the timers from the kiln. Depending upon model the new infinite switch ( because of load)needs to power the line voltage relay which powers the lower elements I believe. It takes a bit of electrical proficiency for sure. Once done the kiln is operated in a conventional manner turning up the power gradually as a manual kiln during the firing.

My best educated guess is this particular kiln is a 4 wire kiln. You need two 120v circuits which means wiring wise, those switches depend on running elements at 120v or two elements in series at 240v split phase with the neutral as a common return path. So a total guess but absent an extremely bad switch …… miss-wired is my guess. Check your electric is two hots, one neutral (all full sized, probably #10 wire) and a ground (usually to the shell). Then check your switch wiring against the circuit diagram. Keep in mind the new switch may not be strictly plug and play as the new switch may have leads that are located slightly different than the old switch. Your diagram I believe, in this manual: https://skutt.com/images/1975-Kiln-Manual-Web.pdf Page 22, look closely at the plug wiring on the page. It takes a 4 prong plug, all prongs have wires attached. The case ground is no longer OPTIONAL btw.

Depending on the load AND the elevation AND the extra envelope losses from top and bottom each section likely fires differently. That is why a three zone kiln is more even than a single zone. They ought to be at different percentages responding to the zone load. So not saying you are perfectly calibrated that’s usually a job to tweak for the first few firings. Try not to get too hooked on FINAL temperature, cones bend by temperature plus time (Heatwork) basically 108 degrees per hour in the final 200f degrees of the firing (center column of Orton). The Orton cone chart shows this for three different ending speeds. The controller will try and adjust for the rate achieved in each section and overall heatwork. I am not sure you have any problem, fire with cones all zones with normal loading to dial this in as close as practical.

My suggestion, replace the corroded bolts and nuts, wire brush the buss bars. The buss bars actually have a larger conductive cross section than most jumper wires folks use to replace them and also keep the connections cooler.they won’t degrade as quickly if cooled effectively. Buss bars have become a high end solution, wire jumpers not as good in my experience. All electrical connections should be very clean and very tightly made up to limit voltage drop and localized heating of the connection.

Underglazes traditionally need to be color tested with their proposed overglaze. If you read the underglaze literature, many will speak about color change at temperature and a common issue: overglazes that contain zinc can affect certain underglazes dramatically. Hence for clears, you will often see “zinc free” clear. The suggestion is always read the literature, which includes the bottle label, sometimes easier to find on the label than the marketing materials, and always test. Many artists prepare a color palette of all their underglazes with one and two coats of overglaze fired to their typical cone to know the color shift in advance.

My arms are fairly long -36” so depending on the piece always braced at my side someway but comfortable. I will steady and touch the piece as lightly as possible with non dominant. I stick the piece to the wheel head - couple drops of water. I try and throw and pre trim as much as practical though so most of my trimming is a minute or two. I do square everything first though, sticking the pot right side up first, knowing the bottom (when cut off the wheel) was perfectly parallel to the wheel head. I very lightly trim the top (and finish the rim) first just to make sure it is dead parallel to the bottom. Then flip it over, trim the foot and done. No wads or GG anymore - just too lazy if I can avoid. Throw as close to finished as possible, saves on clay / trimming, is good practice for me and dries very evenly from top to bottom. Almost all my throwing is on the wheel and not a batt, pots are pre dried a few revolutions before removal with light heat if larger bowls, cut off and set on commercial (cheap / recycled ) paper towel on ware board or old batt (lots of spare batts now). Everything dries quickly and evenly with the paper towel underneath, if I have thrown evenly and close to finished. Never flip most anything anymore, no sticking to a batt pulling my pot out of round, don’t cover many things except overnight if I can trim that day. Cover with bucket instead of plastic if possible - again a bit about being efficient or maybe lazy. Usually throw and trim many shapes, same day if possible.

If you are stuck or unsure they will crimp tight enough a mechanical lug can be a solution. Definitely available at most big box. Cut back the wire until you find nice copper.

From the pictures it also looks crazed on those wares, not sure that is intentional or not.

Looks like a great space! I could definitely picture sitting enjoying the scenery while waiting for a kiln firing.

Looks pretty spiffy to me. Radiant heat on ceiling not likely an issue. A small fan just in case there is a waft of fumes. I like it, I think any challenges, if any, you would solve. Only obscure thought - Maybe cover it after FULLY cooled to minimize trapping warm humid air inside to condense on cold parts later.

My guess - blue mold, butter is a dairy product and usually goes rancid before you can see the mold. It does mold though. Blue - Blue Green common. ”Blue mold or bluish-green mold in the home is usually one of two types of mold, Penicillium or Aspergillus. They are some of the fastest growing molds (usually within 24 to 48 hours) and require very little moisture for their colonies to develop.”

Yes, the better the connection, the less heat. Connections with higher amperage will develop this sooner than others. The terminal block, size of the connector and local cooling can affect the life of the connection. You definitely should replace the wire or cut it back enough to where it is shiny and not corroded. The more corrosion, the more heat causing more corrosion and heat …… you get the idea. An overheated connection can overheat other things like relays etc…. (See below) we keep an eye out for bad connections and fix them before they affect an adjacent pert.

Glazes melt and form a glass so not likely. Typical low fire glaze on the order of 1000C, 1950f so likely far too hot for your wares and have very different expansion rates than steel. Enameling comes closer and generally melts at 1500 - 1600 f. (800 - 860 C) Folks often torch apply enameling for those without a kiln. For decorative purposes you might do the same. Enameling on metal: https://youtu.be/1aQXnT6SY64

Cone 5 with a 15 minute hold ought to get you near cone 6, especially brand new. 22 year old elements that measure exactly to original specification would be very surprising if you have been firing to cone 5/6 with any regularity in the last 22 years. At 12.8 ohms these elements are ready for replacement so the meter needs to be relatively accurate. Might be worth a careful accurate remeasure or measure the amperage, it should be 39.4 amps, if the problem continues and gets more pronounced, look for bad connections, worn relay contacts, over heating breaker …… somewhere a voltage drop is likely occurring. Most items in a kiln need some sort of service within 22 years, so relays that last that long would also be a pleasant surprise as well.

Sounds like a temperature controller that is capable of holding in the 1500f to 1600f degree range while you vary the exposure time. A temperature controller, adequate gauge thermocouple probably easier to use than an infinite switch. So if you are handy, lots of economical temperature controllers out there some include a relay and generally if digital will be your pyrometer. Don’t forget eye protection.

To upload some pictures, reduce the file sizes. That should provide some visual insight for folks. Lots of ways to reduce, here are some possibilities https://www.wikihow.com/Compress-Photos#On-Windows