Piedmont Pottery

Changing the mesh size of the silicon carbide apparently influences the appearance.

PS I suspect that refiring can only smooth/collapse/consolidate previously fired lava glazes, as all their fizz was expended in their first firing.
As the top half of the cylinders indicate thicker application of the glaze increases the foaming -- especially for finer grades of SiC.

If what you are doing works and is easy for you then there is no  reason to change. 
Some claybodies don't rehydrate well if they are semi dried out so for those it's easier to dry the clay until it's bone dry then slake it in water. Bone dry clay will slake down much faster than semidry clay. A slurry mixed claybody thoroughly wets all the particles so clay made from slurry mixed is considered nicer to work with but if what you are doing makes the clay just as good  then no reason to do anything different.
Welcome to the forum!

I substitute strontium carbonate for barium carbonate, 0.75 grams strontium carbonate per gram of barium carbonate in the original recipe.  You will probably have to adjust this a bit, and you will see some shifts in color of the glaze.  Strontium is non-toxic, as opposed to barium.

I substitute strontium carbonate for barium carbonate, 0.75 grams strontium carbonate per gram of barium carbonate in the original recipe.  You will probably have to adjust this a bit, and you will see some shifts in color of the glaze.  Strontium is non-toxic, as opposed to barium.

I routinely use plastic cat litter buckets for collecting and transporting clay slop and trimmings.  I have observed that in areas where the slip dries out along the walls the plastic is coated with red iron oxide, which also adheres to the dried clay.  This is with a white stoneware clay, not a brown or red clay.  So it appears that the trace amounts of iron in the clay are binding to polypropylene surface of the bucket. This makes sense because the surface charge of polypropylene is negative.  I typically throw the dried clay flakes that are covered with iron oxide in with brown clay waiting to be reprocessed.  Over time, my reprocessed white clay will have a lower concentration of iron, although I don’t think it will make a noticeable difference in the color of the clay,  as I don’t think it’s removing more than a few hundred milligrams of iron per batch.

The only issue with humidity is that it can cause the electrical connections to corrode more quickly. That said, my kiln are in an unconditioned space in the midwest and it hasn't been a problem. It has to be pretty swampy for it to be an issue, and even then it's just a matter of replacing the connectors more often. The bigger issue is the moisture from the firings, so definitely install a downdraft vent. As for the cold, if you're looking at a digital kiln, the controller cannot operate below 0 degrees, so if it's super cold out you will need to heat up the space a bit in order to fire. A small space heater next to the kiln will usually do the job. The other issue to be aware of is the safety of having a hot kiln in a barn. 'Barn' can mean a lot of different things, but at it's basic definition it's a space with a lot of flammable materials,  so you want to make sure you have sufficient clearances around the kiln from anything flammable.

For me its a peter Pugger all the way-the 20 VPM is best for classroom size wise
I own a SS VPM20 and an aluminum VPM30
If you are using low fire clay get the Stainless model as it will pit the aluminum model

This definitely happens with lead glazes.  Lead is very volatile at glaze temperatures and will bind to the kiln brick, and then a portion of it will re-volatilize on subsequent firings and will bind to everything in the kiln.  For other potentially toxic metals the extent to which this can happen is dependent on the volatility of the metal at firing temperature.

I routinely use plastic cat litter buckets for collecting and transporting clay slop and trimmings.  I have observed that in areas where the slip dries out along the walls the plastic is coated with red iron oxide, which also adheres to the dried clay.  This is with a white stoneware clay, not a brown or red clay.  So it appears that the trace amounts of iron in the clay are binding to polypropylene surface of the bucket. This makes sense because the surface charge of polypropylene is negative.  I typically throw the dried clay flakes that are covered with iron oxide in with brown clay waiting to be reprocessed.  Over time, my reprocessed white clay will have a lower concentration of iron, although I don’t think it will make a noticeable difference in the color of the clay,  as I don’t think it’s removing more than a few hundred milligrams of iron per batch.

I like the Bailey Nitrate bonded shelves -they are as good as the advancers -I have tested them now with a over 80 cone 11 fires and they are in every way the same if not better as the corners are nicely rounded.
I always buy the best shelves that never warp.
In my 50 years at this I have a stacks of what was best at the time-thick mullit shelves-silicone carbide -the 70s and 80s) -then 1 inch heavy english dry pressed (mid 80s) and then advancers and Baileys Nitrate bonded (early to mid 90s to present). Once you buy these you never buy another shelve and they save so much space and are so light.

I bought Corederlite shelves for my new L&L kiln,  I was told then that they had fixed the warping problem.   I don't have enough firings on them to know if they warp.   I will tell you that I was disappointed that they were heavier than I expected.   You shouldn't have too much trouble lifting the regular 15 inch shelves.   You could buy a Corederlite shelf to use as your bottom shelf,  that is always the hardest one for me to pick up of the 20 inch shelves.    You can always work with half shelves,  some kiln loading instructions recommend using only  half shelves.   I bought the lighter shelves because I am 70 years old and thinking of my future  kiln loading and unloading.     Denice

Many glazes will change color when refired at lower temps, especially those that have a lot of color variation. The only way to know for sure if  glaze will be affected is by trying it. A white or clear glaze is the safest way to go.

I have a Northstar table top slab roller which has been a workhorse for me for 9 years.  16"   Yes, I definitely can get the right thickness each time.  I would assume the Bailey would perform well also.  I use canvas for some things if I want the texture, but one of our members here on the forum told me about using printers blankets.  I like the smooth texture.  I just discovered that you can buy them on Amazon! And I have also used Slab Mat before.   But if you want a nice smooth texture you simply use a rib and smooth out any texture or wrinkles or whatever.  
Roberta

What firing schedule are you using? Flat pieces do not heat or cool evenly- the top heats up and cools down faster than the bottom- so you have to go slowly. Propping them up on stilts or clay wads or broken pieces of kiln shelves will definitely help, but also don't go too fast for the first couple hundred degrees, and go slowly through quartz inversion (the 525-575C range) during both heating and cooling.

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

Buy the e18S-3 now. Get a bigger kiln in the future. You'll be happy to have both, plus you will soon realize how limiting the 18" wide kiln is (I have an e18T-3). Due to the small diameter shelf size (15") and the fact that you also need posts to hold up the next shelf, it's pretty bad for fitting anything but cylindrical pieces. If you make small condiment bowls you can fit a few on a shelf, but you'll still have a fair amount of wasted space. Small cereal bowls will fit 3 on a shelf, but soup bowls will only fit 2. It's great for mugs and small vases, though. Plus the Easy Fire is easier to work on than the Jupiter, and has fewer parts that could wear out.
Call Rob Battey at Northwest Potters Supply when you're ready to order.

Even if it’s older than 5 years, an L&L really holds its value. Selling the small kiln will be easy no matter when you’re ready to upgrade. 

not much to say about your kiln choices. but i just want to 2nd calling Rob @ northwest potters supply. I bought my l&l kiln from him this year and it was a very smooth transaction. he was also super helpful resolving an issue with one of the relays that arrived stuck in the on position.

Delayed cracks can be indicative of a glaze with a thermal COE lower than the clay body.  You might try to increase your glaze COE a bit to see if the cracks still happen.

I have worked with a decal company with original logos and script etc.  They usually send a copy to be proofed.  They are also knowledgeable about their product.  Another suggestion for @Joe from Chagrin Falls is to have a potter create the plates and have a painter/watercolorist paint directly on the bisqued plates with underglaze.  Then the potter can clear glaze then fire.  I have a friend who has worked with me before.   Just a thought.

If I was starting over now I'd invest in nitride-bonded silicon carbide shelves, not necessarily Advancer brand, there are lower cost options from other suppliers.  The lighter weight, durability, and ease of cleaning glaze drips are worth the investment in my opinion.  

It looks to me like you had enough organic materials in the kiln wash to create a reducing environment in the kiln and you got a lot of carbon going into the surface of everything.  If that is correct, refiring with plenty of air available, e.g., peeps open or lid propped open just a bit, should burn off the trapped carbon.  Fire it up to your normal working temperature.

I'm with Bill. Making people calculate volume is a big pain for everyone involved. Asking most people to do that sort of math is not a good idea. Weight is a much easier way to do it, and you can easily have different pricing categories for big wide pieces like serving bowls that take up a lot of volume without much mass, and cups and such that are more compact. Or better yet, just include glazing and firing costs in the price of the clay. It keeps students from feeling like they're getting nickel-and-dimed to death, takes away a cumbersome step in the process, and makes it easier for people to  track and budget their pottery class spending.  I've done it by weight from day one, and it works fine. It's easy enough to figure out the approximate weight of clay in a typical load and calculate all the associated costs of firing and come up with a price. Plus it motivates people to throw thinner with less trimming, and makes them think more about the technical aspects of clay work like avoiding cracks and warping and whatnot that may keep the piece from getting fired.

Mosquito larvae enhanced the plasticity.
(Just kidding. Don’t try it.)

Instead of using a lubricant we put the clay to be extruded into a thin plastic bag open at the die end.  Clean up is just the die and the last few centimeters of the extruder tube.