Bill Kielb

@ChristopherW Ok I’ll take a shot. This was a favorite in 2018 and has been tested and used for a studio clear for several years I know of. Samples in dishwasher forever. Actually moved to new dishwasher as old one wore out. Test piece going on approx 800 wash cycles. It’s Gerstley so not so much a favorite anymore. Glazes often don’t travel well but you are welcome to it. Hope it works for you. This is one of those glazes developed taking the Katz course. The spreadsheet is his, but we have written permission by him to automate the sheet and redistribute. I think he has a new free excel sheet as well. Don’t forget use the 100% batch column.

Just an idea I would suggest following the Orton model. Heatwork prior to the last 100c / 200f is not relevant. Cones have been tested and derived for the final segment at a certain firing speed. This should be easier to code and maybe allow for offsets or a cone table that could be tweaked per application as needed. Work done prior to the fluxed reactions begin is basically reversible and not nearly as important to where the cone will melt.

Hopefully this is more helpful than mysterious. Our clays without fluxes would not melt at a reasonable kiln temperature. So proper full melting is achieved using fluxes and raising the energy of the fluxed mixture enough to get everything to melt. The melting process is not instant so it takes a combination of time and temperature to get this to happen. This predictable melting takes place in the last 200 f of the firing. Cones are made of glaze (including flux) and made to bend with the proper amount of temperature and time at their stated cone value. So a very cool way to measure this total amount of heatwork quite accurately, with one requirement. The final segment speed matches what is written on the Orton cone chart. The final segment is an educated guess as to when we have enough energy to begin these fluxed reactions. Current Orton cone charts I believe set this in the final 200 degrees of the firing, then establish based on the speed being fired what the finishing peak temperature will be. So the most important part is the final 200f and the speed you go in the final segment. 108 degrees per hour gets you the center column of the chart. Overall though, the faster you fire the more uneven a kiln can fire. Slower rates generally lead to potentially more even firings than very fast rates. For cones though and finishing, the final 200f is most important. Oh before kiln sitters and cones etc… potters learned by color of the firing. @Pres can still do this I think (appropriate IR eye protection) sadly in the old days this was a really good skill but without eye protection a likely short lived one.

Normal high temperature crimp connectors are plated but generally do not have insulation which makes them more or less high temperature. Higher quality stuff has welded seams for the crimps. You really only need to design for the area you are working in. Element leads usually use high temp wire - MG traditionally but of late we see kiln manufactures using other types of lesser rated wire but the designs have improved for cooling and use of radiation shields. I assume this is for the lid switch so matching the original wiring temperature and gauge requirement is generally fine unless it has been melting. The existing wiring is stamped with its temperature rating and gauge on the side of the wire so matching or exceeding that should be just fine. Welded barrel crimps are great but not necessary for small electrical loads IME.

Ground fault devices were created just to detect very tiny flow of current. While not exclusive most common source of leakage - damp or wet connections. In North America code generally requires them for receptacles within six feet of a source of water to minimize potential of electric shock.

Me too, rattling around on the floor, not the greatest and mounted you can use regular steel dryer duct and fittings so easy to make leak free. It certainly can go on the floor though didn’t mean to imply it had to be mounted.

There may not be a practical fix. You can try drying each coat of underglaze before applying the next to build it up to opaque. If the underglaze has been dried between coats and simply is not adhering because it’s cone 5 then hairspray might be a winner as well. We have all made this mistake so don’t be too hard on yourself. As far as overglaze, same thing applies and spray application probably gives you the best chance of not disturbing the intricate underglaze and still allowing for a decent buildup of glaze similar to dipping. To me this is hard to do successfully to expectation and if the hand decoration is intricate I think I would seriously remake these and bisque as normal rather than have to redecorate an intricate design a second time. If you try, I definitely would try a single test case before doing them all.

It is really hard to keep it wet enough not to shrink a bit especially with shapes that cannot release somewhat. With a hump or inverted bowl shape the clay can shrink a bit and release up the mold. Your shape is sort of wider at the top than bottom so it will tend to trap the clay and not provide an easy way to remove. Any water that leaves the clay makes it shrink, ever so slightly. It’s really hard to rehydrate clay to its original amount just by spraying. For hump molds it’s good to have a plan for removal as soon as practical just to avoid this issue. I don’t think this is your fault, it’s just very hard to make this shape this way and hard to keep from shrinking just a little during construction. If this was made as a slump or inside this form you would not have these issues.

Maybe dry out all the porcelain insulators as well. If they are damp they will likely trip this. If you can get it working at any level a nice preheat likely dries the kiln best overall. Then never leave the kiln open again.

You can mount it on the wall but the duct that goes between the vent and outside needs to be done well and free of leaks. This duct will be pressurized slightly which. Is ok but then requires effort to be sealed well against any small leaks. The preferred design for exhaust is to suck air through all the ducts so air can only leak in however this is not always possible so the discharge duct must be sealed well so it doesn’t leak. And to answer your question I have dealt with both designs in real life and have an old (bad) pressure retrofit video here https://youtu.be/etpa2Pc9Hug?feature=shared that is sort of a hybrid system using off the shelf stuff and smart design. The hard part will be mounting this and attaching a discharge duct neatly. An angle bracket bolted to the wall could allow you to mount this to the wall but 90 degrees rotated.

@Chalkie76 I have been wondering how long it will be till it surfaces since Neil posted the L&L finding about minute conductivity and kiln brick. Here in the US, kilns aren’t installed on GFCI circuits or RCDs. In the UK the entire household might be protected by an RCD. This is all relevant because even if your kiln did not previously trip the RCD, the brick may now be better connection and may now trip the RCD. If this is the case ( big if here) to test for it I would disconnect the elements from the power source completely and see if the kiln, controller etc…. Operates without tripping the RCD. It won’t heat, I know but if this cures the issue then testing with one set of elements and the second (if present) disconnected could isolate this to one set of elements. Once isolated then one could inspect the elements and grooves in the brick closely to See if there are debris in them causing enough leakage to trip the RCD. Are the brick damp from lack of use? If they prove to be the culprit (big if) kilns end up to be difficult to protect in this way so if code allows then not being powered by an RCD protected circuit may be necessary. I believe the UK has struggled with this issue for a while with new LED lighting, car chargers, inverter powered equipment and now has several RCD devices designed to trip with pulsating DC leakage that may now be required. I think the first step would be to identify if this outlier type problem is occurring for you because of the brick which simply means isolate the elements at the control relays. If the answer is yes, then the magnitude of the conductivity could be measured for a better idea of how to successfully fix this with confidence. If this ends up being the cause and the reason for increased conductivity anything in the power chain such as a dirty ceramic insulator can cause leakage so careful examination and cleaning might be necessary.If it is due to moisture in the brick due to off time or layup of the kiln, then a plan to dry it out might be an effective fix. An odd problem, but sort of easy to at least test for.

This is probably a long shot but - Can you tell us if this was made all in one batch and if so, do you remember the total grams of materials you used. Very often folks making glazes will simply refer to the batch by the material weight, as in, I am making a 5000 gram batch today. Another idea, I if Sue is illustrating the potential effect of Si:Al in Stull then: The original recipe @ 5G silica yields an Si:Al of 5.60:1 (relatively matte in Stull) Raise this to 10g and the new si:Al is 6.11:1 ( definitely less matte in Stull) Raise the silica to 20g and the new si:Al is 7.13:1 ( under Stull 7:1 is the gloss line) So maybe mixing 2-3 fresh small 100g test recipes gets you an idea if it is what you like while illustrating how well Stull applies to this recipe. If you find something you like you will have created a target percentage to hit with your mixed glaze. Then you can go through the calculations mentioned above to figure out how much materials are in your existing liguid glaze and how much silica to add to get to your target. As others have said this recipe has lots of clay so applying this may have challenges. If you like the finished glaze result though you can calcine to make it behave better in application. Maybe simple to make 2-3 very small samples and work from there. It’s always good to start relatively small when testing

If all else fails, a cheap green laser pointer does wonders to cut through most atmosphere noise. Gotta wear IR eye protection though.

While hotter is better to some extent, bisque firings rely on time at elevated temperature. Most bisque firings are in the 10-12 hour range with a decent amount of time to 1000 degrees then probably a fair amount of time from 1500 to your cone. For a manual kiln it’s hard to hit specific temps so mostly slow things down to last in the 12 hour range is always helpful whether cone 05 or cone 04 The time at the upper temperatures becomes important to completely burn out stubborn organics. Slower is generally more complete than faster. Not all clays need the extended burnout and some dark clay manufactures will provide a suggested schedule for their clay.

@GrayB Temperature - your insulation is rated 60c, his is 90c

Interesting spec!! 10555 w / 240 => 43.98 amps. Minimum breaker size 43.98 X 1.25 =54.97. Maximum breaker size = 43.98 X 1.5 = 65.97. So 60 amp is your lowest pick and manufactures specifications. Ran a voltage drop for #6 (copper) cable and it is just over 1%. Check your calculation with the cable you pick. Note 60c non metalic cable is likely only rated at 55 amps, you will need higher quality cable to meet or exceed 60 amps as Hulk mentioned. Any additional 120v load (future) will require a neutral and ground so not sure having one extra no. 6 is useful. 1” PVC conduit definitely allows options and for future expansion. Equipment ground requirement for 60 amps is #10 copper I believe - however you do it. @Hulk is correct, for service and isolation reasons I would install a disconnect. Relying on the plug as a means of disconnect not the greatest of choices for an outside location 60 ft away from being able to shut it off.

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.