Bill Kielb

No you are not over complicating this, follow the manufactures specification. I took a snapshot what I believe your kiln to be (below), if I have the right info, none of the above appears correct. For voltage drop I suggest upsize your wires to limit voltage drop to 1% or less (specifically for kilns). For 60 foot run, that is 120 feet equivalent wire length (Round trip). Depending on which kiln you have it may require a 60 amp circuit, 70 amp circuit - hard to tell without a snapshot of the equipment tag. 43.98 amps is too contrived so that just appears wrong. I would never expect an electrician to suggest more than 80% loading on a residential breaker so that is suspect as well. Your electrician may find the UL requirement for breakers useful: CIRCUIT BREAKERS, MOLDED-CASE AND CIRCUIT BREAKER ENCLOSURES (DIVQ) MAXIMUM LOAD Unless otherwise marked, circuit breakers should not be loaded to exceed 80 percent of their current rating, where in normal operation the load will continue for 3 hours or more. Residential breakers are rated from the factory as 80% devices. 100% rated breakers are generally special and need to be installed in an enclosure approved for them.

Might be interested in some of the discussion here @timthrontonceramics has an interesting comment Re: this composition. Comment here: https://glazy.org/recipes/55141. 0.1:0.9 definitely not something I would design to and far enough from my 0.2:0.8 awareness radar that would subject this to testing for sure. .23 boron, not overly crazy either for that matter. I did pick this version of the original above because it is the famous high calcium clear with the most obvious departure from the original recipe above - less alumina All interesting stuff for sure.

@Mudfish Fantastic post! Go at this logically, not rocket surgery for sure. You should be able to read your meter size , something like : AC250, 5 PSI, 1/2 PSI differential @ 250 cfh flow. So read it or post it if in question. A 250 Cfh meter can supply more, just the pressure drop across it will be 1/2” at that flow. The regulator on the meter will be key. It drops meter pressure to home system pressure of 7”, so its rated capacity will be very important. Again it should be on the tag for the regulator. For a house your street pressure is likely 2 psi or 55.44” wc. We won’t know this, so an assumption likely can be made your regulator has 2 psi input minus meter losses of 1/2 psi at 250 (or rated) cfh flow …….. etc. In other words the gas company really has to determine the total service capacity. It’s just stuff we will never know. To operate on your existing service Your house pressure - very likely 7-8” wc and most of your appliances have 3-1/2” regulators on them. So important to use the right sizing chart for your line sizing and pick a reasonable starting pressure and ending pressure under full flow to get the btuh needed.. We would like to leave your system pressure as is, all your other appliances depend on it. Stove, water heater, boiler, furnace …. All of them regulate your current pressure form prox. 7” down to 3-1/2” (typ) Start with what does the current kiln require or what will you expand into in the future How much = orifices @ desired pressure X no of burners - let’s pick a pressure less than max (7”) leaving some room for pressure drop in the pipe run, fittings and valves… let’s use 5” wc Sizing existing Pick from your favorite orifice table: https://www.gordonpiatt.com/wp-content/uploads/2021/07/Natural-Gas-Orifice-Chart-7.E.80.5-Rev-3-05.01.pdf. 1/8” Dia. Orifice @ 5” wc = 48,200 btuh per burner X 5 = 242,000 btuh total. Is that enough? Not sure but let’s finish. pick piping from chart knowing you likely can drop from 7” to 5” if need be. Most charts limit to 0.3” wc drop so 2” buffer is somewhat conservative here. Table pg 4-3 http://ecodes.biz/ecodes_support/free_resources/Virginia/fuelgas/pdfs/Chapter 4_Gas Piping Installations.pdf This manual will let you add equivalent lengths for fittings etc… but by now you get the idea of leaving yourself room by way of pressure drop, orifice sizing etc…. To make the situation best work for what you have available. As long as you can move the desired btuh at a realistic dependable pressure your design should be good. There are lots of ways to get there. Solid knowledge of the basics, likely gives you many options for best solution. Only other last thought, work in inches of water column. All low pressure stuff is measured that way. 1 psi = 27.72”. Low pressure stuff = Water Column. Medium pressure stuff, 2 PSI. While folks will refer to ounces or 1/4 - 1/2 psi it tends to lead to mistakes. Stick with water column unless venturing toward medium pressure stuff. Other than that, it looks like you are on the right path to figure out just how many btuh you need or will need in the future to run this for and now should have a way to reasonably size it.

The dragon24 I believe is a 16500 watt kiln which means a minimum circuit size of 86 amps or as Neil mentioned a 90 amp breaker and wiring. Your dad’s service may only be 100 amps so this is likely too large for his studio. I would ask for a picture of the equipment tag to confirm how this kiln is configured and that it is single phase for sure. The numbers given seem to be erroneous.

@PeterH Looks like masking and looks like the shadowing may have been airbrushed underglaze. That’s what strikes me

It was created and tested so studio brush artists could layer and paint as they desired so that is an ideal aspect if this glaze works for your clay. That picture looks fairly matte so its base configuration may be fine. Else you can increase silica till you get the look you like. It won’t cover crazy thick underglaze, covers fairly thick stuff though so I suggest testing your colors worst case first to find limits with your material. BTW - when over glazing, the heavily underglazed areas will be much less absorbent. I found it helpful to spray a uniform coat and dry the heavy underglaze areas before spraying another even coat. In this way one can get an even application of the overglaze making it as clear as practical and uniform thickness.

I think it likely works, but I really want pictures to unveil if it has a regulator downstream, what is the regulator model #? 1/8” is ok - sort of, but I would rather have the number stamped on the orifice. If not, burner model, measure the orifice with a number drill instead of guessing. Piping is easy to figure out, but knowing the actual required capacity is most useful. The piping chart below is for low pressure with 0.3” drop and probably at 3.5”. Operating pressure. Just looking at 1” 60 feet without fittings at the above referenced pressures, maybe 200000 btuh max ……….. Is that enough - no way to know - updraft, or down draft, again who knows? Pictures, a few measurements you can very easily get there but it will take some effort. Will 1” pipe at house pressure work? It will do something that’s for sure. Will it fire well - maybe, maybe not, impossible to tell. I really need pictures to develop questions or estimate supply line sizing for real. Absent that - maybe it will work great.

@Suresh Sundaram Just an fyi - this recipe was designed fairly matte. If you read through the description note just adding silica will take this toward glossy. It was created so folks could dial in their preferred level of desired matte. It has had some really good reviews over the years, but there definitely are folks who are not fans. It has worked on a decent variety of clays and the attraction as a studio glaze has been the ability to simply dial in your desired gloss as well as melt well over fairly heavy underglaze. Hope it works for you.

First before tweaking your sitter get a few firings under your belt especially with a kiln that’s filled. It sounds like it might be fairly close. If not and it’s just too far away, Sue McCleod has a decent how to on her website I believe. Orton cone photo below, notice the very small difference especially if the cone is not fully touching. At four o’clock we are only speaking of a degree or two. You may be just fine calibration wise.

Post a picture of the kiln equipment tag and a picture of the gas valve train especially any regulators that are piped in this circuit - even if just a pilot regulator.

How do you know it slightly underfired? It’s a manual kiln so 2 hours on low, 2 hours on medium, then high till end of firing and see if this gets you in the 5-8 hour range.

All very available HVAC ductwork parts, available stuff - For that fan You should be able to use a 12” flanged take off, 12” hard pipe duct and or 12” flex duct to isolate vibration or as needed. Steel duct attachment would be 3 screws for round rigid, worm drive clamp is easy and goof proof for the flex. Seal all seams with metalic duct tape UL181- P for rigid or UL181-FX for flex connections. Duct sealant (brush applied) is more permanent than tape but taking it apart for maintenance a bit of a pain. Advise adding a decent backdraft damper and well thought out discharge louver. Cheapest flanged take off I could spot below: The take off from the original OP appears to be a bit adapted for use (might be the photo), connection shown below, typical.

Just so you know a little of the where and why of all the caution here, electricians seem to have difficulty sizing breakers and wiring for kilns. The general rule for kilns (known as a continuous resistive load) is simple in that not less than 125% of the rated load, nor more than 150%. Your kiln is 48 amps so a 60 amp breaker and wiring is recommended by the manufacture and fits this rule. For everyday stuff, Electricians are usually taught never to load a breaker more than 80%. Brand new from the store, they are rated at 80% of their load. In your case a 50 amp breaker typically would only be used for a 40 amp load following this rule……... So that ……. somehow a 50 amp breaker was used coupled with the initial 120v hookup of a 2 pole breaker raises flags as to how it was all done.

Dick has a great point remember no skimping! As long as we are covering the electrical bases, the ground wire is considered an equipment ground. It is sized based on the maximum load on the circuit - 60 amp breaker- and should be sized a minimum gauge by checking in table 250.122 (NEC). Your electrician should know this and verify, but a 60amp Equipment ground needs to be #10 or larger copper wire by memory but don’t trust my memory - double check. No skimping here either. Come to think of it ALL the wire needs to be copper, JIC he is using or planning on something else.

14-50 R is still a 4 wire device rated at 50 amps. Just checking you are squared away seems your electrician is not familiar with a 3 wire 240v circuit. You should have: A 2pole 60 amp breaker, #6 wire and three wires are run, 2 hot wires (L1&L2) and a ground wire (No neutral for this type of circuit). Must have a ground though to protect you. No skimping, these are the manufactures requirements.

It would be interesting to see just how many departed significantly. Lots of old glaze recipes fall into a reasonable range around 0.3:0.7. I would love to see real comparison data on this, anecdotal often has the potential for perception bias.

Maybe food for thought - since it’s really hard to maintain temperature and lower the gas as well as shuffle your dampers to maintain reduction this might be a very small / slight drop and hold actually. Especially if you are not significantly dropping the next cone. Maybe an idea to explore - drop and hold pretty popular to heal some pinholes. Might lead to establishing an easier end of firing sequence.

I would definitely agree - it should not be viewed as a rule for sure. Even Katz believes working within a range is practical. Definitely more research, but something to help design within and when significantly outside a reasonable range that knowledge would hopefully cause folks to investigate. For folks that are science oriented, proving something true is usually impossible just because all conditions never can be accounted for. From a design standpoint I find it as helpful or a bit more than relative references we see in glazes such as High, as in high alkaline - how much is high, who knows? Same with high calcium matte or high alumina matte. They are all somewhat helpful references though as folks sought to characterize for the benefit of others so totally dismissing those efforts probably not productive or fair. So more successful testing under as many conditions as practical likely would increase confidence for sure, dismissing the results entirely, without reasonable contrary testing probably not the best path either.

Just a thought- You may want to set you SG first for what works best with the particular glaze ( Not necessarily a predetermined number) from there you may be able to adjust viscosity as needed to improve performance.

I am not a hold person as to me it simply adds heatwork. In a practical sense there are folks who fire one cone lower but add a hold to get to the next cone heatwork without the peak temperature. In that case firing to cone five with a fifteen to twenty minute hold often gets one to cone six. (Usually verified with cones) Why do that? Some glazes do not like higher peak temperatures. Some underglazes change color significantly with peak temperature. It is a pretty functional way to fire a cone to two cones max higher without hitting the actual peak temperature. Firing higher or for longer has never healed pinholes for me, often made them worse. Drop some temperature and hold however has helped on s some of my pinhole situations. whatever works for you and your desired glaze results is likely the best answer. Whatever is done, I strongly suggest always nice to have cones in place so you genuinely know how much heatwork was done. As to suggested time, 15-20 minutes generally gets you to the next cone.

Not to worry, folks have made glazes forever and experimented looking for predictable ways to characterize what happens. They publish their findings or research and you get to decide if it is useful to you. Commercial glazes have the issue of - what is in them and how does one correct a defect such as crazing. The good part is commercial glazes don’t use lead anymore (for the most part), vanadium pentoxide etc… generally because someone found out it was a bad thing. If you mix your own then you know what is in it and can reasonably test for durability, fit, etc…. to your satisfaction, before selling it or giving it as a present for human consumption. I think it does help to inform but definitely not for everyone.

Sorry the reason I mentioned the firing to cone 6 making a cone 04 glaze less durable because it was a good example that durability and boron were not tested or at least meaningfully tested and meaningfully quantified. I also mentioned it because many 04 glazes will fire just fine to cone 6 - Stroke and coat and look alike glazes seem to fall in this category. The only point was, while excess boron is certainly a thing, we generally should not conclude the current research predicts durability, hence the example that using it to predict an 04 glaze durability fired higher seems to be at odds using it to strictly predict durability. I do not think that was the focus of the 2012 research. Instead we were given a reasonable amount of research that indicated flux ratio’s outside a reasonable range could indicate a lack of durability. Why design your glazes there? Maybe test durability of those glazes approaching less reasonable ratios with a heightened awareness of the potential to be less durable. The gloss test is a doable one and relatively repeatable (if you have a decent gloss meter and maintain uniform measurement protocols) but it is dimensionless really so as a practical indicator and even trend indicator, likely fine. It is dimensionless so maybe no direct predictable correlation to longevity of service. I think the flux ratio research has shown merit and potential to be reasonably useful as qualified above but Boron and durability has not necessarily been tested and quantified. So I believe appropriate to say, why waste the material it’s not necessary to use that much. I do not believe what was written in 2012 was intended as a durability study on Boron in glazes……… just an indication of where did they appear best to melt.

Fire in the kiln? Could be a bit of smoke.

Gas fired appliances need ventilation, the simplest form would be a properly sized natural draft hood. Natural draft hoods are one of the simplest designs because they are simply a hood above the appliance with some space available for dilution air (room air) to also rise up the flue pipe. This open space on older natural draft appliances (boilers, water heaters …) was often called the draft diverter. Quite often before the flue could warm sufficiently this space would allow the cold downward draft to be diverted so as not to blow the pilot out in the off cycle. What COULD it be? Common would be a properly designed flue for the kiln not allowing the cold backdraft at startup. You mentioned HVAC issues, well gas appliances need their own source or combustion air as well sized for the appliance and positionally sized in one of several very specific ways to combat stack effect, dilution air requirements etc… Further: exhaust HVAC appliances need makeup air. Proper design and accounting is important so as not to defeat any natural draft appliances. Does the studio have a paint spray booth or other exhaust appliance affecting this? What could this be? It’s simple stuff but takes real design experience and the potential to be a real health safety issue with carbon monoxide or just a nuisance issue like pilots blown out exists. My experience often these are designed by folks not skilled enough to do so or a failure to follow the manufactures design requirements. Hidden issues like other exhaust appliances with makeup air issues are common as well. If folks are silent or secretive about it, maybe they are not skilled enough to understand all the potential design issues. It’s fairly straightforward but truly requires combustion air zone training in addition to flue design skills. I can’t tell you how many times I have seen direct vents installed for natural draft. My best thought here is find an HVAC contractor with these skills and the ability to understand and follow code requirements. The solution is generally easy, just not necessarily intuitive and unfortunately found more in older techs than younger as these appliances disappear from use in favor of sealed combustion higher efficiency stuff. zI could be several things unfortunately, I included a simplified drawing of some of the interactions of these required airflows you may find of interest in this thread https://community.ceramicartsdaily.org/topic/39240-skutt-envirovent-still-allows-fumes/?do=findComment&comment=251190

I would test, should be fine with the silica but I think I would default to alumina for more worry free separation. Watch everyone else’s wares though, easy to get this on other folks finished work. Folks often add Alumina to their wax for more control of the application however burning out large quantities of wax requires big ventilation so the alumina wax is a nice solution for keeping lids from sticking but probably not so much for separating sheets