No real changes to the unity formula, just revised to use the materials I keep in my studio. Calcined part of the kaolin to avoid issues with it being so high. I'll try to post a photo tomorrow.
@SunsetBay, my preference is to have at very most EPK in a recipe at 20%. If you calcine some of the EPK it will reduce the shrinking (and gelling in the bucket) of both glazes.
EPK has a LOI (loss on ignition) of 13.20%. What this means is you need to reduce the amount of calcined EPK in the recipe by 13.20% (by weight) from the original amount. If you use 20% as the maximum of raw EPK then make up the balance with calcined EPK the V.Slate Blue would be 20 EPK plus 8.68 calcined EPK. Spearmint would become 20 EPK plus 6.94 grams of calcined EPK.
Measure the specific gravity of the glaze when you test it and also take note of number of dips and how many seconds you dip for. I would suggest you do some test tiles to check this and see which result you like the best. If you find it still crawling then decrease the amount of EPK further still and replace it with calcined EPK using the same math. Subtract 13.20% of the weight from the calcined EPK.
To calcine EPK just put some in a bisqued bowl and run it through a bisque firing. It's handy to have a supply of it ready to use.
I would suggest dropping the bentonite altogether, don't need it in either recipe.
Here's a revised Spearmint recipe that I use in my studio, and I've never had problems with it:
Gerstley Borate 11.5
Frit 3134 5.53
Neph Sye 4.27
Whiting 17.58
Calcined Kaolin 8.22
EPK 22.38
Flint 30.53
In my experience, heat is heat and time is time. I have not noticed much difference between my bigger kiln full of mugs and programmed for a slow cool and my little test kiln with 2 mugs programmed for the same slow cool. Both of my kilns have the same Bartlett Genesis controllers so I know both pre-programmed slow cools are are the same. Unless your older E23 has a Genesis as an upgrade (L&L now installs Genesis controllers as default) you would need to dig into your controllers to precisely match the slow cools. (But minor differences in a slow cool usually don't cause serious differences in the glaze, so don't get your knickers in too much of a knot.)
However, note that the Bartlett controllers all have an adaptive feature in the cone-fire programming that adjusts the final temperature in real time based on the actual rate of increase being sensed in the final segment. If you push the button for a fast cone X that has an aggressive heating rate, the controller will run past the assumed final temperature to accomplish the proper cone bend as shown in the Orton cone table. Similarly, if you set a slow fire, it will stop short of the assumed final temperature just as shown in the Orton cone table for a slower ramp. The kicker here is that if your elements are worn and your kiln just can't keep up the assumed 120F/hour for the medium column in the Orton cone table, the controller will automatically scale back the final temperature and you will still get a good cone bend (until things get so bad you get the dreaded E1 error). But, and here is the big BUT!, if you program a custom ramp-hold that you think exactly repeats a cone-fire profile to a particular final temperature and your kiln has worn elements that are slowing down, the controller no longer adapts. It will fire to the specified final temperature even though the elements are slowing down, and it will be overfired. So, be careful when programming a custom ramp-hold and be sure your kiln elements are in good enough shape to actually maintain the programmed ramp(s).
