Dick White

Many years ago, one of the students in the college class lost the bottom nut from the extruder die holder while cleaning it in the cleanup bucket in the sink. Irritating, but not the end of the world to have to go to the hardware store for a replacement nut. We periodically scoop the sludge from the cleanup bucket into the main recycle barrel, and when that barrel is full, I pug the recycle in to a proprietary mix that is so proprietary that even I don't know what I put in the pugged clay logs. Despite the unknown mix, it's usually nice enough to work with for class demos and experimental practice work. About a year and a half later, I was making a batch of Empty Bowls, and felt a lump in the wall of the cylinder. Thinking it to be an air bubble, I poked it with my needle tool, but it was a hard chunk. So I dug it out, and there was the long lost nut.

DigitalFire can tell you about the usage of most of those. https://digitalfire.com/material/list

There is some conflicting information about the first firing floating around, both from different kiln manufacturers, for different purposes, and even within the same manufacturer's instructions. L&L's printed manual has long instructed owners of their new kiln to do an initial break-in firing of the empty kiln (but with the furniture) slow bisque to cone 5 (yes, five, not oh-five) with a 3 hour preheat for the dual purpose of seasoning the elements to develop a protective oxide coating and to set the cement used during manufacturing to hold the kiln bricks together. Their newest manual indicates these instructions are for both the Dynatrol and Genesis controllers.
Conventional wisdom by some other kiln manufacturers instruct owners of their new kilns to do the initial firing slow to 04. This is consistent with the recommendation from the manufacturer of the Kanthal elements for seasoning newly installed replacement elements, again to develop a protective oxide coating on the wire. Out on the interwebs, many commenters who own these other brands of kiln will adamantly (but incorrectly) assert that new owners of all brands of kilns should do the initial firing to 04.
And now we have this new video from L&L for programming the first firing on a Genesis controller that instructs a glaze firing to 04 with a 1 hour preheat. However, if one looks around on the L&L website, there is another video for programming the older Dynatrol controller for the first firing that is consistent with the printed instructions, i.e., slow bisque to 5. Is the basic kiln constructed differently for a Genesis vs. Dynatrol controller that it would need a different initial firing? I don't work there, so don't take my word for it, but the conflict seems fishy to me. With 3 instruction sources to choose from (the printed manual and 2 videos), I would go with the 2 that are consistent, i.e, the printed manual and the Dynatrol video. But maybe that's just because I am a recovering accountant...

There is some conflicting information about the first firing floating around, both from different kiln manufacturers, for different purposes, and even within the same manufacturer's instructions. L&L's printed manual has long instructed owners of their new kiln to do an initial break-in firing of the empty kiln (but with the furniture) slow bisque to cone 5 (yes, five, not oh-five) with a 3 hour preheat for the dual purpose of seasoning the elements to develop a protective oxide coating and to set the cement used during manufacturing to hold the kiln bricks together. Their newest manual indicates these instructions are for both the Dynatrol and Genesis controllers.
Conventional wisdom by some other kiln manufacturers instruct owners of their new kilns to do the initial firing slow to 04. This is consistent with the recommendation from the manufacturer of the Kanthal elements for seasoning newly installed replacement elements, again to develop a protective oxide coating on the wire. Out on the interwebs, many commenters who own these other brands of kiln will adamantly (but incorrectly) assert that new owners of all brands of kilns should do the initial firing to 04.
And now we have this new video from L&L for programming the first firing on a Genesis controller that instructs a glaze firing to 04 with a 1 hour preheat. However, if one looks around on the L&L website, there is another video for programming the older Dynatrol controller for the first firing that is consistent with the printed instructions, i.e., slow bisque to 5. Is the basic kiln constructed differently for a Genesis vs. Dynatrol controller that it would need a different initial firing? I don't work there, so don't take my word for it, but the conflict seems fishy to me. With 3 instruction sources to choose from (the printed manual and 2 videos), I would go with the 2 that are consistent, i.e, the printed manual and the Dynatrol video. But maybe that's just because I am a recovering accountant...

There is some conflicting information about the first firing floating around, both from different kiln manufacturers, for different purposes, and even within the same manufacturer's instructions. L&L's printed manual has long instructed owners of their new kiln to do an initial break-in firing of the empty kiln (but with the furniture) slow bisque to cone 5 (yes, five, not oh-five) with a 3 hour preheat for the dual purpose of seasoning the elements to develop a protective oxide coating and to set the cement used during manufacturing to hold the kiln bricks together. Their newest manual indicates these instructions are for both the Dynatrol and Genesis controllers.
Conventional wisdom by some other kiln manufacturers instruct owners of their new kilns to do the initial firing slow to 04. This is consistent with the recommendation from the manufacturer of the Kanthal elements for seasoning newly installed replacement elements, again to develop a protective oxide coating on the wire. Out on the interwebs, many commenters who own these other brands of kiln will adamantly (but incorrectly) assert that new owners of all brands of kilns should do the initial firing to 04.
And now we have this new video from L&L for programming the first firing on a Genesis controller that instructs a glaze firing to 04 with a 1 hour preheat. However, if one looks around on the L&L website, there is another video for programming the older Dynatrol controller for the first firing that is consistent with the printed instructions, i.e., slow bisque to 5. Is the basic kiln constructed differently for a Genesis vs. Dynatrol controller that it would need a different initial firing? I don't work there, so don't take my word for it, but the conflict seems fishy to me. With 3 instruction sources to choose from (the printed manual and 2 videos), I would go with the 2 that are consistent, i.e, the printed manual and the Dynatrol video. But maybe that's just because I am a recovering accountant...

Ok, now download the firing log and feed that sweet thang into @jay_klay_studio's graphing program to visually see the tracks of the 3 sections. And if you really want to have some fun, add another 9999 drop all the way down to 100 after your regularly programmed cool to log how looooonnnggggg it takes for the last several hundred degrees. Several times over the years I've printed the extended graph of a few kilns as a teachable moment for the students of the virtue of patience, i.e., "Can I get my piece tomorrow?" "No, next Friday."

DigitalFire can tell you about the usage of most of those. https://digitalfire.com/material/list

Ok, now download the firing log and feed that sweet thang into @jay_klay_studio's graphing program to visually see the tracks of the 3 sections. And if you really want to have some fun, add another 9999 drop all the way down to 100 after your regularly programmed cool to log how looooonnnggggg it takes for the last several hundred degrees. Several times over the years I've printed the extended graph of a few kilns as a teachable moment for the students of the virtue of patience, i.e., "Can I get my piece tomorrow?" "No, next Friday."

Ok, now download the firing log and feed that sweet thang into @jay_klay_studio's graphing program to visually see the tracks of the 3 sections. And if you really want to have some fun, add another 9999 drop all the way down to 100 after your regularly programmed cool to log how looooonnnggggg it takes for the last several hundred degrees. Several times over the years I've printed the extended graph of a few kilns as a teachable moment for the students of the virtue of patience, i.e., "Can I get my piece tomorrow?" "No, next Friday."

Ok, now download the firing log and feed that sweet thang into @jay_klay_studio's graphing program to visually see the tracks of the 3 sections. And if you really want to have some fun, add another 9999 drop all the way down to 100 after your regularly programmed cool to log how looooonnnggggg it takes for the last several hundred degrees. Several times over the years I've printed the extended graph of a few kilns as a teachable moment for the students of the virtue of patience, i.e., "Can I get my piece tomorrow?" "No, next Friday."

Ok, now download the firing log and feed that sweet thang into @jay_klay_studio's graphing program to visually see the tracks of the 3 sections. And if you really want to have some fun, add another 9999 drop all the way down to 100 after your regularly programmed cool to log how looooonnnggggg it takes for the last several hundred degrees. Several times over the years I've printed the extended graph of a few kilns as a teachable moment for the students of the virtue of patience, i.e., "Can I get my piece tomorrow?" "No, next Friday."

I am a big fan of the L&L kilns. I am not personally familiar with Evenheat, Jen-Ken, or Olympic, but from all the noise in the various pottery groups on the intertubes, most of the users of those brands appear not to be production users, and most of them seem to be happy enough with their kilns. I have worked with both Skutt and L&L in several community studios with a lot of volume, and much prefer the L&L. The Skutt PK models are designed for high production environments and are pretty sturdy kilns compared to their regular line, but you can get an equivalent level from L&L with their quad element option. If you want even firing, the L&L has zone control (multiple thermocouples) as standard; you will pay extra for it from Skutt. If you get zone control from Skutt, it will manage the separate zones independently as expected, but the 3 thermocouples cannot be calibrated separately (at least in those at one studio I work with that has Skutts), you get one thermocouple offset that applies to all 3 regardless of whether a particular zone is running hotter or cooler than the others. If you are going to do your own maintenance, the hard ceramic element holders in the L&L make element changes a breeze. The Skutt pins and channels in the soft brick are hateful. As for the SSRs, they seem to be an available option for only a few of the Skutt models, so do some more comparative research if that is priority for you. Regarding the Skutt touchscreen vs. the Genesis (which is now standard on L&L kilns, you will pay extra for the Skutt KMT versions of their kilns), you have the question backwards. Both are made by Bartlett, but the Skutt version is in different form factor to match the way they designed their control panel. The screens and features are mostly comparable, but Skutt does not offer much of a written user manual, instead they build an FAQ of sorts into a help menu behind a button on the screen. Further (which borders on criminal IMO), Skutt has removed the slow cool option from the cone-fire programming. If you wish to slow cool a firing, you must construct a custom ramp-hold program that mimics the desired cone-fire program and append additional segments for the slow cool. In addition to being inconvenient, you lose access to the adaptive capability of the cone-fire method. (With this feature, either controller will monitor the ramp rate in the final segment into the target cone and automatically modify the target temperature (e.g., lower the target temperature if the ramp is lagging due to worn elements) in accordance with an algorithm licensed from Orton. In a ramp-hold program, the target temperature is absolute as programmed, which means a slower ramp due to worn elements will result in an overfire.) The Genesis has an on-off checkbox in the settings for appending a slow cooling segment to a cone-fire program. The only feature Skutt offers over the standard Genesis is an extra cost subscription to a cloud data service into which the controller will automatically upload data from every firing for later retrieval and analysis. The Genesis only retains data for the last 10 firings. If you don't subscribe to the Skutt Kiln Link cloud service, their version also retains data for just the last 10 firings.
The foregoing is my opinion and should not be confused with what anybody else may think..
dw

It is #6 copper wire for all three wires, this I know I confirmed with the electrician. 

Do not replace the 50 amp breaker with the required 60 amp breaker unless the wire is 6 ga. or better.

When defloculating with sodium silicate, a funny thing happens if you go too far. It begins to thicken rather than get even thinner as you would expect. And you add more and it gets worse. Solving the problem requires understanding how defloculation occurs. The clay particles are sensitive to the acidity or alkalinity of the water. If the glaze slurry is too loose and separating quickly, a small dose of an acid, such as epsom salts or vinegar will flocculate it. If the glaze slurry is too thick, a small dose of an alkaline, such as sodium silicate or soda ash, will deflocculate it. But, as mentioned, if you deflocculate with too much sodium silicate, it starts gelling. Because the underlying problem is too much alkalinity, you just need to neutralize it with some acid. It seems crazy to flocculate this glaze that has gotten too thick from over defloculation, but that is what you need to do. Scoop out some and try it with a few drops of saturated epsom salts solution or vinegar.
p.s., in your recipe, did you mean manganese dioxide instead of magnesium dioxide?

When defloculating with sodium silicate, a funny thing happens if you go too far. It begins to thicken rather than get even thinner as you would expect. And you add more and it gets worse. Solving the problem requires understanding how defloculation occurs. The clay particles are sensitive to the acidity or alkalinity of the water. If the glaze slurry is too loose and separating quickly, a small dose of an acid, such as epsom salts or vinegar will flocculate it. If the glaze slurry is too thick, a small dose of an alkaline, such as sodium silicate or soda ash, will deflocculate it. But, as mentioned, if you deflocculate with too much sodium silicate, it starts gelling. Because the underlying problem is too much alkalinity, you just need to neutralize it with some acid. It seems crazy to flocculate this glaze that has gotten too thick from over defloculation, but that is what you need to do. Scoop out some and try it with a few drops of saturated epsom salts solution or vinegar.
p.s., in your recipe, did you mean manganese dioxide instead of magnesium dioxide?

@Min et al, I just pulled the tile after 24 hours half submerged in 30%* cleaning vinegar. There is no change in gloss or color (we use this glaze with a bit of copper and some tin/zirco for a nice turquoise). I will go shopping to find some plain lye (Drano brand has other stuff in it) - when home-brew testing, I like to hit the sample tile with something stronger than kitchen cabinet chems (since I run my dishwasher so infrequently, it would be next year before I would complete the Katz-recommended 30 cycles...).
*Grocery store vinegar is diluted to an acidity of 5% - sometimes. In recent years as manufacturers everywhere try to reduce costs by invisibly reducing quantity in the same package, some grocery vinegars are now 4%. That might not make any difference in your oil and vinegar salad dressing, but if you like to make your own pickles, you need to check the label and make sure you are getting a 5% vinegar. And there, I did it again, took the pottery discussion in another direction. Now we can share recipes for pickles...

As I see it, there is a lot of good work establishing ground zero for the perfect glossy durable midfire glaze - flux ratio of 30:70, Si and Al molar within limits, Si:Al ratio around 7-8, boron molar within limits, etc. Yes, perfect, but boring glazes. Mayco Stroke and Coat, a solid performer from 06 to 6.
In my glaze chem classes, I tell them to consider theoretical perfection, but also realize there is are a lot of more interesting effects to be found outside of ground zero. Some of it may not be durable, though some may be just fine, do your tests. I have to this point stayed away from subjective experience with this particular recipe, but one of the reasons it is so popular in my community studio is because of the interest it creates. When layered with certain others of the studio glazes, we put the Amaco drizzles to shame. It is a solid glaze by itself, or Amaco/Mayco Flux in the same bucket.
Why? In my studies of glazes, it is the high boron in this one when layered with other lower boron (conventional theoretic levels) glazes. Higher boron levels create a borosilicate glass. Lower boron levels create an alumino-silica glass (not quite soda-lime bottle glass, but the chemistry is moving in that direction). Layered borosilicate glass and alumino-silica glass do not mix to a homogeneous blend, but rather they are immiscible and flow through each other in rivulets or create a faux-oilspot effect. Now I have the student's attention (and if they are not careful, a kiln shelf to clean). As DuPont said 90 years ago, better living through modern chemistry.

As I see it, there is a lot of good work establishing ground zero for the perfect glossy durable midfire glaze - flux ratio of 30:70, Si and Al molar within limits, Si:Al ratio around 7-8, boron molar within limits, etc. Yes, perfect, but boring glazes. Mayco Stroke and Coat, a solid performer from 06 to 6.
In my glaze chem classes, I tell them to consider theoretical perfection, but also realize there is are a lot of more interesting effects to be found outside of ground zero. Some of it may not be durable, though some may be just fine, do your tests. I have to this point stayed away from subjective experience with this particular recipe, but one of the reasons it is so popular in my community studio is because of the interest it creates. When layered with certain others of the studio glazes, we put the Amaco drizzles to shame. It is a solid glaze by itself, or Amaco/Mayco Flux in the same bucket.
Why? In my studies of glazes, it is the high boron in this one when layered with other lower boron (conventional theoretic levels) glazes. Higher boron levels create a borosilicate glass. Lower boron levels create an alumino-silica glass (not quite soda-lime bottle glass, but the chemistry is moving in that direction). Layered borosilicate glass and alumino-silica glass do not mix to a homogeneous blend, but rather they are immiscible and flow through each other in rivulets or create a faux-oilspot effect. Now I have the student's attention (and if they are not careful, a kiln shelf to clean). As DuPont said 90 years ago, better living through modern chemistry.

@Min et al, I just pulled the tile after 24 hours half submerged in 30%* cleaning vinegar. There is no change in gloss or color (we use this glaze with a bit of copper and some tin/zirco for a nice turquoise). I will go shopping to find some plain lye (Drano brand has other stuff in it) - when home-brew testing, I like to hit the sample tile with something stronger than kitchen cabinet chems (since I run my dishwasher so infrequently, it would be next year before I would complete the Katz-recommended 30 cycles...).
*Grocery store vinegar is diluted to an acidity of 5% - sometimes. In recent years as manufacturers everywhere try to reduce costs by invisibly reducing quantity in the same package, some grocery vinegars are now 4%. That might not make any difference in your oil and vinegar salad dressing, but if you like to make your own pickles, you need to check the label and make sure you are getting a 5% vinegar. And there, I did it again, took the pottery discussion in another direction. Now we can share recipes for pickles...

Mea, this is a interesting recipe that shows up in a variety of places. The version you have is very close to one that we have been using in the Audrey Moore/Wakefield (Ffx County Parks) studio since forever.  That one is Gerstley 50, EPK 17.5, Silica 32.5 (our Gerstley vs. your 3134, about the same effect; your EPK and silica are reversed from ours). From a chemistry standpoint, the massive amount of Gerstley or 3134 generates so much boron that it could/should be a low-fire glaze - and indeed I have seen it in published collections of earthenware glazes. At the same time, the alumina and silica levels are quite high, and so the glaze is robust enough to survive at cone 6. With the demise of Gerstley, I am reformulating it to use 3134, and my revised recipe becomes similar to yours. Something to consider - 30 EPK is a lot to have in a recipe, and will cause issues with shrinkage and cracking (leading to crawling during the firing) so replace half of it with calcined EPK. It just so happens right now I have a test tile with my revised recipe soaking in vinegar, so I will come back in a day or so with the outcome of that.

As I see it, there is a lot of good work establishing ground zero for the perfect glossy durable midfire glaze - flux ratio of 30:70, Si and Al molar within limits, Si:Al ratio around 7-8, boron molar within limits, etc. Yes, perfect, but boring glazes. Mayco Stroke and Coat, a solid performer from 06 to 6.
In my glaze chem classes, I tell them to consider theoretical perfection, but also realize there is are a lot of more interesting effects to be found outside of ground zero. Some of it may not be durable, though some may be just fine, do your tests. I have to this point stayed away from subjective experience with this particular recipe, but one of the reasons it is so popular in my community studio is because of the interest it creates. When layered with certain others of the studio glazes, we put the Amaco drizzles to shame. It is a solid glaze by itself, or Amaco/Mayco Flux in the same bucket.
Why? In my studies of glazes, it is the high boron in this one when layered with other lower boron (conventional theoretic levels) glazes. Higher boron levels create a borosilicate glass. Lower boron levels create an alumino-silica glass (not quite soda-lime bottle glass, but the chemistry is moving in that direction). Layered borosilicate glass and alumino-silica glass do not mix to a homogeneous blend, but rather they are immiscible and flow through each other in rivulets or create a faux-oilspot effect. Now I have the student's attention (and if they are not careful, a kiln shelf to clean). As DuPont said 90 years ago, better living through modern chemistry.

As I see it, there is a lot of good work establishing ground zero for the perfect glossy durable midfire glaze - flux ratio of 30:70, Si and Al molar within limits, Si:Al ratio around 7-8, boron molar within limits, etc. Yes, perfect, but boring glazes. Mayco Stroke and Coat, a solid performer from 06 to 6.
In my glaze chem classes, I tell them to consider theoretical perfection, but also realize there is are a lot of more interesting effects to be found outside of ground zero. Some of it may not be durable, though some may be just fine, do your tests. I have to this point stayed away from subjective experience with this particular recipe, but one of the reasons it is so popular in my community studio is because of the interest it creates. When layered with certain others of the studio glazes, we put the Amaco drizzles to shame. It is a solid glaze by itself, or Amaco/Mayco Flux in the same bucket.
Why? In my studies of glazes, it is the high boron in this one when layered with other lower boron (conventional theoretic levels) glazes. Higher boron levels create a borosilicate glass. Lower boron levels create an alumino-silica glass (not quite soda-lime bottle glass, but the chemistry is moving in that direction). Layered borosilicate glass and alumino-silica glass do not mix to a homogeneous blend, but rather they are immiscible and flow through each other in rivulets or create a faux-oilspot effect. Now I have the student's attention (and if they are not careful, a kiln shelf to clean). As DuPont said 90 years ago, better living through modern chemistry.

And back to arguing about the Katz documents - all those graphs are based on a flux ratio of 30:70 R20:RO. Stull ran his infamous chart on this flux ratio. There is wide agreement that this ratio is optimal. There is also modest agreement about silica and alumina molar limits of generally 2.5 to 5 for silica and .25 to .5 for alumina for mid fire with a Si:Al ratio of around 7 or 8 being a nice glossy glaze. There is less published documentation showing that when keeping the flux and Si:Al ratios constant, cone 10 melt occurs higher up the diagonal on the Stull chart and cone 04 melt occurs lower down the diagonal. There is also wide agreement that boron is helpful at mid-fire and necessary at low-fire, with the Katz diagram showing recommended molar levels across the range of temperatures. But when we mix all that together and do something different, we don't really have any guidance, so as @davidh4976 just said, we talk past each other. The recipe @GEP is asking about is completely outside of conventional limits . The flux ratio is 22:78 - Katz spoke of not going above 35:65, but nothing about going below, where this one is significantly below the gold standard. The Si:Al ratio is 7.8, nice for a glossy, but the molar levels of 4.1 and .52 are in the cone 10 range. The boron molar level is at .72, a bit high for cone 04 (i.e., off the Katz chart). So what we have is a high calcium semi-matte (based on the flux ratio) with cone 10 glass (based on the silica and alumina molar levels) and cone 08 boron molar levels that comes out a nice glossy cone 6. As @Bill Kielb said, "there are an infinite number of fired combinations to which research could be applied."

@Min et al, I just pulled the tile after 24 hours half submerged in 30%* cleaning vinegar. There is no change in gloss or color (we use this glaze with a bit of copper and some tin/zirco for a nice turquoise). I will go shopping to find some plain lye (Drano brand has other stuff in it) - when home-brew testing, I like to hit the sample tile with something stronger than kitchen cabinet chems (since I run my dishwasher so infrequently, it would be next year before I would complete the Katz-recommended 30 cycles...).
*Grocery store vinegar is diluted to an acidity of 5% - sometimes. In recent years as manufacturers everywhere try to reduce costs by invisibly reducing quantity in the same package, some grocery vinegars are now 4%. That might not make any difference in your oil and vinegar salad dressing, but if you like to make your own pickles, you need to check the label and make sure you are getting a 5% vinegar. And there, I did it again, took the pottery discussion in another direction. Now we can share recipes for pickles...