Piedmont Pottery

Unless you're really set on building your own, I would keep a lookout for a decent used kiln. From a time and money standpoint it would be the best way to go, even if you have to drive a bit to get it. The most difficult part is cutting the grooves in the bricks. Brick dust chews up anything it gets into, so know that any power tools you use may be sacrificed. Build the controller box so it can be wall mounted, not mounted to the kiln. Have a jumper cord coming off the kiln that plugs into the control box. The boxes I've built run about $200 for a 50 amp kiln, including everything but the controller. For a 20 amp kiln you could drop $30-40 off of that since you'd only need a small relay, outlet, etc. You can get a good 3-button kiln controller for $200.
The big questions are how much work do want to do, and how quickly do you want to be firing? Building your own electric kiln is about 10 times as much work as a small gas kiln. There are a lot of little parts needed to make it work. A control box alone uses about 20 different parts if you count wire as one part. There's also all the little terminal ends, screws, nuts and bolts, etc. I'm not trying to discourage you, I just want you to realize what you're getting into. I'm assuming you know enough about electrical systems to do it all safely? Start making a list of everything you need. It will be lengthy, and sourcing all those parts in small quantities can get expensive.

Some time ago I posted about challenges with wollastonite clumping.  I have now found a process which is helping with this issue.  I utilize one of these flour sifters when weighing out the wollastonite.
  I sift the material directly into a pan on the balance until I have the necessary amount.  It's pretty low tech, but it works.  Perhaps not feasible for large-scale batches, but I'm usually making 1-2kg batches of most of my glazes, and it works fine for that.
 

Some time ago I posted about challenges with wollastonite clumping.  I have now found a process which is helping with this issue.  I utilize one of these flour sifters when weighing out the wollastonite.
  I sift the material directly into a pan on the balance until I have the necessary amount.  It's pretty low tech, but it works.  Perhaps not feasible for large-scale batches, but I'm usually making 1-2kg batches of most of my glazes, and it works fine for that.
 

Some time ago I posted about challenges with wollastonite clumping.  I have now found a process which is helping with this issue.  I utilize one of these flour sifters when weighing out the wollastonite.
  I sift the material directly into a pan on the balance until I have the necessary amount.  It's pretty low tech, but it works.  Perhaps not feasible for large-scale batches, but I'm usually making 1-2kg batches of most of my glazes, and it works fine for that.
 

Some time ago I posted about challenges with wollastonite clumping.  I have now found a process which is helping with this issue.  I utilize one of these flour sifters when weighing out the wollastonite.
  I sift the material directly into a pan on the balance until I have the necessary amount.  It's pretty low tech, but it works.  Perhaps not feasible for large-scale batches, but I'm usually making 1-2kg batches of most of my glazes, and it works fine for that.
 

For me throwing the whokle thing on the wheel is faster by far. The time is trimming a foot.The wares are solid and do not warp. The compression is good and no memory issues with the clay .

Update for anyone following this thread:
 I have now finished my firing schedule experiments and didn't come up with a schedule that worked well.  So far there are  two possible solutions:  (1) refire and (2) only glaze one side (to allow gases to escape from the unglazed side). I will use two firing schedules:  my original firing schedule (the one that gave good results on Rutile Green, and Variegated Blue) and Min's suggested firing schedule which gave a good results for Studio White for the next set of experiments --  thickness of application and adjusted glaze chemistry.   
The results for the over 20+ firings are:
peak temperature:  the best results were in the range  2165-2190.  I used both the 108 ramp and 27 degree ramp.  Worse results were experienced going higher or lower than this range.   soaks at peak:  increasing the length of a hold from  2190: 5 - 30 minutes ; 2165: 18 to 30; and 2133: 30 to 75  didn't improve the results. slow cool rate:  tried 500, 125 and 60 and got worse results the slower it went.  The VB developed blisters with the extended hold.   drop and hold soaks:  soaks in the range  1900 to 2090 (going down by 10 degrees) didn't make any difference in the results for the Wollastonite Clear or Studio White.  The only success on the VB and RG were in the original firing schedule.   Next predicted update in one month.  

The material survived the bisque firing, strongly suggesting it was not organic.  It sure looks like iron oxide to me.

I'll fire some chips in the bisque kiln this weekend.  If it is tannins they should burn out.  This is also city water, not well water, so I expect only low levels of tannins.

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

For me it would be faster to just throw the plates on the wheel from the start rather than using the slab roller.   However, I do find that a foot ring adds stability to plates during firing.  Have you considered using a slump mold instead of throwing the slabs?

For me it would be faster to just throw the plates on the wheel from the start rather than using the slab roller.   However, I do find that a foot ring adds stability to plates during firing.  Have you considered using a slump mold instead of throwing the slabs?

I'll fire some chips in the bisque kiln this weekend.  If it is tannins they should burn out.  This is also city water, not well water, so I expect only low levels of tannins.

A group of potters I belong to used to do a raku firing as a fund raiser.  The members would make items in advance.  We would haul all our equipment out to the site of a local fair and  the public would buy a piece or 2, glaze under instruction of a member.  The pieces would be dried on the lid of one of the 2 kilns we had going and put into the fire when ready.  I don't think we ever had an explosion.  Lin

This is the way I learned this particular pinhole theory but to my knowledge and what I have been taught, like fired COE,  the fired characteristics cannot be obtained from the glaze formulation and measuring at temperature for just one composition has its own complications.
+ one from me realizing kilns generally don’t have powered cooling cycles so they cool at their rate (thermal mass being significant here) and you simply establish holds along the way. Multiple holds can give you step control though so closer to a defined rate of cooling. To my knowledge alleviating the surface tension issue involves trial and error though. Some of the randomness to multiple trials could be the different natural rates that things are actually cooling. So if your kiln cools very quickly at top end, then your holds could be more material and reliable.
Hopefully I am wrong and someone here has the magic, but from my experience testing is necessary. Pinholes can have other causes though so you may want to explore those cures as well.
I will add that temperature differences from shelf to ware or outside of a ware to inside of an open shape always seemed highly unlikely just because ceramic conducts heat pretty quickly, generally much faster than typical heating and cooling rates it is subjected to. Still, if you find a solution based in that theory then it works for you.
I believe you need to test to find the best answer for a glaze combination. One solution I really liked was to fire short of peak temp using a hold to still make cone heatwork and doing a drop and hold from there. In my experience glazes can pinhole more so at higher firing temps. So firing one cone lower with a fifteen to 20 minute hold drives the heatwork to the desired cone but without the peak temperature. Something maybe worth trying with your established drop and hold from there.
Finally, if this reads crazy complicated, it’s just me not being able to adequately simplify, someone likely will have a simple fix.

Eye-candy
 

Hi and welcome to the forum.
Crazing means the glaze doesn't fit the claybody it's on. A simple analogy would be a pair of jeans a few sizes too small for someone, they are going to stretch and rip. This is what your glaze is doing on the clay. It has nothing to do with taking them from the kiln at 100F and firing cooler will just make it worse. Since it's a commercial glaze the simplest thing to do is ask your supplier or Laguna Clay which body they recommend for this glaze. It is hard to see crazing with some glazes, try rubbing a permanent marker or calligraphy ink over the glaze then wiping it off, the crazing should be visible then.

Trimming tool I mentioned above arrived yesterday. Edges were hardly sharpened at all. I gave it a try this morning, not great. I'll try sharpening it but definitely will not be buying another. 

Move it in sections, don't try to lift it all at once. Unhook and remove the lid. Stack the sections in the truck, making two stacks if you can. Put foam board underneath each section. The pink house insulation board works well. Set down the wall sections first, with the lid and floor slabs on top (if the floor is a separate piece). Foam board separating everything. Wrap it all up with plastic stretch wrap and secure the load as best you can. I use a cargo tarp and that works really well. If you put straps over the top, put foam board between the straps and the kiln. Don't crank down too tight with straps or you could crack the bricks.

The oil worked like a dream! We found a 3-in-1 solution, cleaned off the grease, and have a slab roller again. Thanks for the help!

I got one this year partly because of the ability to export log files. But they're incredibly hard to read. I'm a software engineer so I made a website to extract and graph the info (and then got really carried away). 
Menu on the home page has a demo feature if you want to give it a spin. 
www.fire-graph.com

The dip in pressure you are getting is the vacuum finally getting to the mixing chamber.  When the mixing chamber is full and you are mixing mode, there is a seal of clay that forms between the back chamber (where the vacuum port is) and the mixing chamber.  When you start pugging it allows a small gap to form along the mixing shaft that then removes the air from the mixing chamber.   This is more pronounced if the mixing chamber is overstuffed.
After getting the vacuum established in the rear chamber using mixing mode, I switch to pugging mode and slow speed.  Usually where there is about 4-8 inches of clay out of the nozzle the seal will break that releases the vacuum into the mixing chamber.  Keep slowly pugging until the gauge shows the vacuum back up.  then reverse direction to mixing and allow the extruded clay to be sucked back into the chamber (be sure to replace the cap).  After a few second of mixing, then return to pugging and extrude the full batch.  Usually, the first 6-8" has some minor bubbles so that just goes back in the next batch (or I keep that aside for handles and other attachments).

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.

I'm not convinced there's much evidence that 0.3:0.7 is the most durable ratio. I mean even in that ratio there's so many different fluxes included that there's too many variables for it to be a useful rule.

I have made  ten exterior murals so far.   You need have the size of mural you want to make and then a design that works with it to start.   Your design need to have small,  medium and large pieces in it and a flow of color and design that will encourage the viewers eyes to follow.   I have made terracotta and C6 stoneware clay murals,   using a cone 6 hand building  clay will give you the best results.   I see you live in PA and have a lot of freezing weather,  your clay needs to vitrified and your glaze has a perfect fix.   Any crackle in the glaze will allow water to leak in  and freeze popping the glaze off.  This is a good time of the year to make some test tiles and lay them outside and let the ice and snow.   I made a two foot mural and  mortared it on a cement board and placed it in the yard to see how it would hold up.  It survived the winter so I knew I was set to make more murals.  I wouldn't recommend making a mural for a horizontal surface after several years the weather takes it toll on it.   I have made two ext floor murals that were on  porches.  The tile was a purchased one inch porcelain tile that holds up freezing condition and epoxy grout.  It was the grout that didn't hold up,  it popped out of the grooves and molded.   I will be glad to answer any questions you have.       Denice