Bill Kielb

This may help, spent one summer working with Bristol glazes at cone 6. Fairly similar recipe as posted with the simple concept of taking a titanium matte and making it a bit of a runny matte to capture the refraction of the crystals as they accumulated. End result blues and violets and a touch more towards red / yellow with a tiny bit of iron. Variations around the zinc base and melting point more so around the amount of boron. Some samples below, if this is the look you are interested in I will attempt to locate the trials I have and post.

He can change the amperage of the breaker, but not really the volts to 250v. Are you tripping the breaker? If so, what size do you presently have? Here is the info I have for a TNF 66 kiln, per the manufacture, it may help. 240v, 20 amp 2 pole circuit breaker. Definitely get the electric right. Your electrician should confirm with the nameplate on the kiln as well.

The epoxy, top picture. Squeeze out on in a mixing area or on a mixing pad you can throw away, mix thoroughly for 1 minute then apply everywhere you need it, even to fill gaps. Set items together accurately and wipe all excess neatly off with mineral spirits or similar.

Interesting late notice when looking at the Duncan service manual. 208 v elements are 8.66:ohms which places you at 6000 w when operated at 228v which is 26 amps. Here that current draw would require at least a 30 amp breaker and number 10 wire rated for 30 amps. So gauging the elements down but having them wound as if 208 v could be a reasonable solution to the low voltage.

gas hoses and pressure regulators.com this one is stainless and does require quick disconnect though. Getting all the parts to fit up is usually the issue as this is premium low pressure and the quick disconnect is a great feature but you will need to match up everything for connection which will take a bit of reading and matchup. Mr heater probably does not service large btu loads.we should sketch it out to make sure everything fits end to end really. The regulator pictured will require a 1/2” mpt to 3/4” fpt adapter. Anyway, depending on your regulator we should draw everything out to make sure sizes and gender matchup.

Amazon? Internet? I have used these with good result.

Ok, so there are two pressures we need to address so let’s see if I can describe it so it makes sense. The pressure needed at the burners has to be approximately 11 “ (INCHES, less than 1/2 psi). Regulators used for this purpose generally have a maximum inlet pressure of 10 psi and reduce it to 11” (Inches). Also the regulator must be capable of supplying at least 290,000 btu, which means it will likely have a 3/4” diameter or larger outlet size at 11”” of pressure. Capacity problem 1/2” diameter hose /pipe at 10 psi can easily carry 500,000 btu over many feet of distance 3/4” diameter pipe / hose at 11” of pressure is needed to carry 500,000 btu 10-20 feet so the usual choice (most economical and lowest pressure for safety) is to hard pipe from the kiln with 3/4” pipe to where the gas bottle will be (within 20 ft of the kiln) and install a two stage propane regulator at the propane tank. If we do that we only need ordinary gas pipe from the kiln to the bottle, a two stage regulator (economical) and a flexible connection from the pipe to the second stage regulator (pigtail). So a quick rough drawing And some parts, economical regulator (horizontal mount) A safe removable way to connect the regulator to the tank leaving a low pressure short pigtail to connect from the piping to the regulator which need to match 3/4” pipe thread on one end and whatever our regulator outlet thread is, once we pick a regulator.

Typical two stage regulator for RV’s are rated at 160,000 btu and generally are 3/8”. To simplify this, How many btu is your kiln rated (nameplate). For that matter what kiln model and maybe post a picture of what you are hooking up. A barbecue tank is usually 20# and has 4.7 gallons of propane full and can produce a bit more than 400,000 btu. If your kiln is 100,000 btu per hour, that’s about 4 hours of firing on a barbecue tank. So 15 gallon may be a typo, or maybe not. I posted some tank examples below just to give you an idea. Give us name plate, pictures, make, model etc………. this is something likely easily solved but confusing to pick if you have not experienced it before. Folks here can help. This likely is easy and economical using RV style stuff which are mostly 2 stage regulators, which you likely need.

Sorry to hear that actually. 3% rule of thumb here is usually allowed but for kilns for obvious capacity reasons less is suggested. No point in starting with a brand new kiln in effect worn 3%. There is a special rule for continuous resistive loads to protect the breakers from repeated heating in North America. The rule here would be no less than 125% of the rated load and not to exceed 150%. Often this takes care of the voltage drop issue, a nice side benefit. Most countries address these loads similarly to protect the protection devices so you may want to research. Electricians not used to working on kilns are often not familiar and tend to under size things. Most often the rules for maximum loading on a breaker fit well with this standard. So for example, here for normal breakers you are only allowed to size them so normal loading does not exceed 80% of the rating. Which, interestingly is the reciprocal of 1.25 or 125%. Actually intuitively who would put a 30 amp load on a 30 amp breaker? It does happen though. For your use you may want to have elements re-wound to make the original wattage at your rated voltage. (Total kiln R= V(squared) / Watts) Of course all protection and wiring would need to be upgraded as necessary and I would suggest clear re-labeling is a must. BTW we just went through this in another thread and as an FYI, kilns with 4 watts per interior square inch are usually most robust. Hope that helps! Previous thread : https://community.ceramicartsdaily.org/topic/30261-paragon-dtc-800-kiln/?do=findComment&comment=228236

Probably the most important part - your method works for you. I will say that excess pressure out the lower burner port lines up with a bit too much restriction or reflected flame in the flame path, especially if your kiln is not pressurizing from the top down. Under normal circumstances folks find a suitable gas pressure then begin closing their damper very slowly until some pressure (flame) exits the lower spyhole and they are in heavy reduction. With the restriction in the flame path it sounds like you will need to free this up a bit, it likely is too restrictive. One thing at a time though.

My feeling is the burner port size confirms you were going in reduction because of lack of secondary air. And the better performance seems to support that result as you were able to fire faster because your burners put out more. subjectively, To me I like the use of a shelf as your bag wall so it becomes a glowing red hot radiant panel and enlarges your flame trench a bit especially in a small kiln. I like the wall to be significantly less mass that the wares in the kiln. Also to me my next try would be with the target brick to the right or up against the right hand wall to provide some deflection forward and because of the coanda effect it still will drive about 1/2 the flame to the rear and to the right wall of the kiln. One thing for sure, I have rarely been able to solve by changing multiple things. It’s often too dynamic so unless you get lucky with first placement it makes things really hard to solve. So whatever changes are made I think one at a time is the most effective way to creep up on a solution.

just to keep the brewmasters at bay: I think that’s a really solid assumption. It can be less for a mixture of things in water but those things would need to be a lower sg and miscible in water. A real world common example likely would be alcohol. For clay, I can’t think of anything light enough so to speak.

This might help - the desired sg is the one that works best for a glaze and an application method. Often it’s tested and recorded once known. I like a three second dip, others prefer differently. Additionally for a clear glaze for example I like them applied as thin as practical and with a uniform 100% coverage. So desired sg to me is dependent on what’s being applied and application method as well as desired thickness. In other words It’s usually a recorded number for a particular product based on experience

Just an FYI, he also has low voltage. 228v fully loaded. Probably needs that stabilized before you tune the loop

Yep, definitely makes sense to read the nameplate.

Nope probably very high. Best to read the nameplate of the kiln but I think he picked orifices that translate to 90k btu per burner and 8 burners based on a previous size of #28. Reading the nameplate would be best and not working in PSI also really could be relevant here IMO

The circuit breaker will likely tire at some point from the heating. Best case it will trip prematurely, worst case is it will fail to trip until a higher amperage. Probably not a good idea to wait too long to get it wired properly.

Experimentation is good, my thought is maybe start at 5:1 or high fours. Your alumina levels are relatively high, I get it, it’s easy to get your ratio that way but at some point it isn’t gonna melt. As an example: For cone six glazes I like to stay 0.58 Al or less, they generally are fairly stiff in this range in my experience. 0.45 boron is great at cone 04, increasing can create its own issues so if you follow the Katz research 0.45 for cone 04 is great, exceeding it, especially in excess often is not considered better. Those glazes have a large amount of clay as well so not entirely sure how they will mix up. Feldspars are a nice source of silica, alumina and fluxes as well, not sure if you have a pure preference to clay and Frits In the end thoughtful experimentation is great though so note your results. You may be able to find some already made mattes on Glazy or elsewhere to experiment on as well than just creating one from scratch. Right now, you really don’t have glazes that require silica as it’s entirely sourced from the materials. You may be able to create simpler allowing for the addition of some silica.

Color response can be a thing as well with use of certain fluxes. I would suggest (in a well melted glaze) a test blend by varying the Si:Al from 4:1 to 7:1 for a true matte just to get a feel of going from let’s say dry matte toward semi gloss or gloss is a worthwhile exercise to experience IMO.

Yes, you guessed it watts per cu ft of available load plus watts per sf to offset shell surface losses. Most kilns have about 110% brand new and after wearing 10% they need element replacement to make it. Cone 6 kilns often have less than their counterparts. This is the norm, not a lot of kilns are made with 115% capacity new. So you are indeed fortunate. Reaching cone 7 with a hold makes total sense this way. Operating your elements at top temp though with a hold will shorten their life a greater percentage than just normal operation. How much is relevant to how over designed the kiln is. At 3 watts per square inch, life is short. 3.5 w / sq in, better, sort of typical. 4 watts per square in- you are in the longevity bonus range. L&L has great published data comparing the loading as well as the effect of 3” brick

You can just buy it, a common circuit board etching solution. Chlorine gas release (mustard gas would be primary concern) If you make it, it does not need to evaporate but does require oxidation with peroxide or bubbling air as a final step. Etched a lot of circuit boards as a kid, use all reasonable care.

Here is a little engineering fun that could spark some additional thought. The more laminar, the better. One can do tricks with laminar flow. A fun practical example, 14:02 is probably most relevant. https://youtu.be/y7Hyc3MRKno

OMG! The one thing guaranteed to overfire your stuff! I assumed it came programmed with the kiln. Setting an R type thermocouple and using another type in its place is one sure way to over fire. Really good catch, a well known issue that happens on occasion and most manuals even warn of it. It’s rare to happen and really hard to figure out unless it’s obvious someone was in there changing it. Nice! And you got a lot of experience too. Just be sure to confirm what type you have.

If it was 100% unattached there would no reading, so maybe, definitely tighten and make good. Thermocouples increase in output as temperature goes up so a bad connection could give you a low reading but that would really speed up the firing because the controller would think it’s lower and fire harder. At 9.9 ohms (10%) your elements would be considered fully worn, so depending on the accuracy of your meter they don’t seem fully worn although 9.4 is halfway there. Can you safely measure the voltage: Kiln off and kiln fully on just to see if we are losing a percentage energy there. It doesn’t take much so worth measuring I think. We also need to know the rated voltage and wattage on the nameplate to compare with the measurement. Good find on the tcouple, but doesn’t seem likely that that would logically account for the symptoms. All else fire a test load, maybe some test bowls, add some mass as in shelves just to get closer to a normal load. It’s troubling because you have not fired a full load yet and your symptoms are, it is slowing above 1170. The good thing is you can monitor the speed and see if it slows down near the end. If so, we will need to find where the power loss is. Voltage measurement (kiln operating- all elements) for sure if you can safely do it. If the voltage is low that will be significant.

Maybe, but the thermo couple slows down after 1170 and displays room temp ok but fails a 25C correction. Her comment was an observed 15 minute delay which is much like a 15 minute hold even with a 25c depressed final temp.. Firing rates don’t slow down if the thermocouple is miscalibrated. She seams to bisque Ok, not necessarily over fire in the bisque because the controller or thermocouple is off. I think her symptoms point to being under powered so checking would be wise. I have reasons for what I see, I really don’t see anything that contradicts the progression. Under powered can be elements, relay, connection, voltage so I think its wise to check. Not sure why anyone would discourage it actually?