Hulk

Thank you!

Hi tman!
Can you elaborate on what you are aiming for?
I'm not clear on the bottom - are you leaving it bare?
Are the glazes you are using fluid - do they sag and run? Are you aiming for a thinner glaze application at the bottom to "catch" running glaze?
Almost all my work is functional and rests on a bare clay foot ring.
I use masking tape for a clean sharp line. Pulling the tape while the glaze layer is still moist minimizes dust...
Dipping upside down, the glaze is thickest at the rim, thinnest near the foot.
Wiping away glaze - seems easier when the glaze is still moist, especially if the point is to wipe some, but not all of the glaze layer away.
When the glaze if fully dry, wetting it, then waiting a few moments for the moisture to penetrate is almost same...

Added: most often, I'll buy 3M "Contractor Grade" (#2020) masking tape; it's buff colored.
For small wares, bargain tape can work for straight lines - small wares are light!
I've used the blue tape when we have some left over from somewhat else.
I'm putting the tape on and taking it off the same day; at most, the next day.
For curvy lines, quality tape is more important; it cuts cleaner, has better stick, and curves better.

Hi Kalyssa, welcome to the Forum!
A few of my bats clunk;  the fit on the pins isn't tight. The clunking goes away once the clay is closer to being centered - that's been my experience; once the force on the clay is constant and even, the bats don't move.
You might need a few more bats? Compare/contrast your problem bat against one that fits snugly to confirm?

Hi tman!
Can you elaborate on what you are aiming for?
I'm not clear on the bottom - are you leaving it bare?
Are the glazes you are using fluid - do they sag and run? Are you aiming for a thinner glaze application at the bottom to "catch" running glaze?
Almost all my work is functional and rests on a bare clay foot ring.
I use masking tape for a clean sharp line. Pulling the tape while the glaze layer is still moist minimizes dust...
Dipping upside down, the glaze is thickest at the rim, thinnest near the foot.
Wiping away glaze - seems easier when the glaze is still moist, especially if the point is to wipe some, but not all of the glaze layer away.
When the glaze if fully dry, wetting it, then waiting a few moments for the moisture to penetrate is almost same...

Added: most often, I'll buy 3M "Contractor Grade" (#2020) masking tape; it's buff colored.
For small wares, bargain tape can work for straight lines - small wares are light!
I've used the blue tape when we have some left over from somewhat else.
I'm putting the tape on and taking it off the same day; at most, the next day.
For curvy lines, quality tape is more important; it cuts cleaner, has better stick, and curves better.

I figured out what was causing this, but wanted to allow for a lot of firings to make sure. It turns out that inside the digital controller that I added, the 'wire-end' of the compression terminal on one of the internal wires was a bit too close to the controller's metal housing. I disassembled the controller (which was bought in one preassembled piece), and found signs of arcing. I put a good bend into the terminal, put everything back together, and have had no problems now over many, many firings.

You are all very sweet, thank you.  Nice to have a community where we try to help each other out, share info, and encourage one other.  Many I time I've asked for help around here and gotten great input.  So I'm glad if I can give a little something back.

I was recently asked about a pouring box for mold making. Here are two versions I use in the studio.  The image with the bulbous object is my main pouring box. The pieces are 3/4" plywood cut into 5"x15" boards. I then screwed 1"x1" strips onto the ends which provide a lip for the small "C" clamps. Very quick and easy to assemble a box in any dimension.
The second image shows another box variation that I use often for flat castings. The sides of the box are 2"x2" pieces of pine. (In his case I also used some 1"x2" strips.) The 2x2 pieces are labeled as "turning blanks" and come in a variety of wood types.  (Woodworkers use them to make stairway balusters.) Because they are square and stocky they don't need much bracing other than a little clay at their base. 
The mold on the left I free formed and did not use the box to limit the plaster. (I shaped it by hand.) The mold on the right I filled the box with plaster and then ran a straight edge along the tops of the wood pieces which resulted in a mold that was evenly thick. 
 

To wrap up my little saga on this first ceramic Porthos - he successfully sold at auction yesterday for more than $1600 and I am quite pleased.   Yay!
Alas, I am having issues with his mold so there will be no more of this edition forthcoming until I resolve those issues or make an entirely new set of plaster mold pieces.  I master molded the original plaster mold pieces using silicone but I ended up using a shore hardness 1 step softer (30A instead of 40) and I'm having problems with the new plasters being warped and NOT fitting back together correctly.  Even though the silicone rubber pieces are each in their own mold boxes around the sides (but not the bottoms).  Grr.  I should have known better!  Moral of that story is do NOT be lured by being able to get two gallons of platinum silicone for half the usual price on sale when they are not the correct shore hardness I need.  Close, but no cigar.
Ah well, maybe I can fix the issue by making simple plaster jacket molds for the bottoms of silicone molds so they can't possibly warp from the weight/pressures of the wet plaster filling them.   I think there is a very slight gap there that's sagging so it may end up being an easy fix.  Maybe.   I'll just have to try it today and see.
Meanwhile I have already printed a replacement Porthos of the same size and version to make a new mold from.  I made the first mold set to cast him in pieces for testing my bone china slip I'm making from scratch here in studio but I also want to be able to cast him as close to whole as possible for earthenware production anyway, so back to the drawing board with claying up...  I'm also working on molding him in a larger version so I may well have the big boy casting before I have this smaller version back into production.  One never knows!  Murphy's Law always rules whether I like it or not.

Hi B.H., Welcome to the Forum!
Good questions.
Excepting small/test kilns, expect your kiln to be rated for 240v, single phase*.
Also expect to run a dedicated circuit for your kiln.
Firing clays and glazes produces fumes. Adequate ventilation is a must, in my opinion.
To fire cone 8, a kiln rated to at least cone 10 will last better than a lower rated kiln.
There are several archived threads here where some of your questions are discussed at length; I'll look later today, have to run just now!
 
*Not sure what the electric standard/convention is in Southampton.
Here in California (USA) we have 240v single phase at our home. Three phase is typically only found in commercial buildings...

All right.  For an initial test I have mixed up about 1/3 cup white earthenware slip (cone 06-04 that I got locally and ball milled it a few days) and to this I added about a tablespoon of vinegar.  Mixed it up and it bubbled a little bit (a lot of the recipes mention vinegar but not sure why exactly).  By morning it had settled on top as a clear fluid and the slip had become rather unplastic, sort of more like wet sand than slip.  I poured off the excess fluid.
Then I added about 1/2 a teaspoon soda ash and mixed it in well.  It tried to form a hard crust so I had to put it into one of my mortars and use the pestle to grind it smooth again.  I have a rather large ball mill but alas, not a little one.  Maybe I should make myself a smaller porcelain jar and little balls for just such things ... but I digress!
The last thing I added was 1 ml of sodium silicate, mixed well then a touch more.  It became very creamy and lost the hint of grittiness.  I have no idea how it will preform but now I'm going to test it.  Not sure if the vinegar was actually any help at all or not but the soda ash and sodium silicate made sense.  I'll let you know how well it works or doesn't.  I'm going to test it filling in tiny defects and a crack in a bone china horse sculpture I want to glaze.  My initial reaction is it has a good feel, much like the bisque mender I had been using and loved.
I can always color adjust afterwards with a little airbrushed opaque white underglaze if needed over it to blend it in before I move onto coloring the piece.  Wish me luck!  I'll be firing it to cone 04.
 

I have been spending a lot of time and energy replacing my Gerstley Borate glazes. The new ones are coming along, but they just don’t have the same glow and magic. I am trying to push the limits of “how much boron can I get away with?”
The good news is that switching to Fabi Talc in place of Texas Talc has been seamless. 

I've had to reformulate over half of our pottery glazes, both cone 6 and cone 10 to accommodate the end of Gerstley Borate, Custer, and Texas Talc. Using frits for GB, Mahavir Potash Feldspar for Custer, and dolomite/whiting for talc. Of course, all of the recipes needed changes to amounts of silica, kaolin, etc.
The tough ones seem to be the recipes that were "breaking" glazes or used some sort of lithium. Those took some tweaking and testing to get to a similar match to the old glazes.
Our local supplier has switched from Custer to G-200EU in their clay body mixes without any noticeable difference.

The clays I like from "nearby" vendor (about a hundred miles) have been reformulated.
The whitish stoneware seems about the same, the red behaves a bit differently.
My intent was (still is!) to look into alternatives this year; I've enough Gerstley, Custer, and Texas Talc to last a few years, however, years go quickly...

The clays I like from "nearby" vendor (about a hundred miles) have been reformulated.
The whitish stoneware seems about the same, the red behaves a bit differently.
My intent was (still is!) to look into alternatives this year; I've enough Gerstley, Custer, and Texas Talc to last a few years, however, years go quickly...

I have a favorite glaze that uses talc, and up until lately have had quite a bit to use in glazes that I bought several years ago. However this last glaze batch found me with none left. Last year I had heard about  a shortage of talc, and believed I would have to reformulate my glaze to work with a different component, maybe dolomite. Imagine my surprise when I found Fabi Talc listed at SC. So I will be ordering some to use in my glaze. However, it makes me wonder if anyone has had to reformulate glazes or clay bodies due to a lack of materials? 
QotW: Have you had to reformulate any clays or glazes due to a shortage of materials?
 
best,
Pres

All the time now. Gerstley is gone and Gillespie is not a perfect match. 3134 requires a complete rewrite of the recipe. Custer is gone from the market, but I still have some. G200EU might be ok, haven’t tried it yet. Still have some old Amtal talc, but some Fabi is in my future. What’s next?

It’s a good question. People end up finding their absorption happy place, some are unsatisfied with anything over 1%, others with 0.5%, I am good if the mugs don’t weep or get wickedly hot in the microwave. I believe that’s below 2%. The ASTM standard for vitrified is 0.5%.
My understanding is similar to yours, about firing range. I could be wrong about this, but my general observation is the lower the maturation temperature of the clay, the narrower the firing range. It’s certain the closer you get to vitreous the less wiggle room you have, at any cone. 
In his book Clay and Glazes for the Potter, Daniel Rhodes says, “Fired stoneware should have an absorption of 3 percent or less.” That’s on page 42 of my edition. I was taught, a few decades ago, that absorption below 2% makes reliable pottery but you should shoot for below 1.5%. Talking to potters over the years gives me the impression that the desired number has crept down since Daniel Rhodes wrote his book. 
Now, back to low fire, is it suitable for everyday use? Not without some careful consideration. There are a lot of variables, so many it seems like a subjective question. It depends on what you’re willing to put up with, or what you’re asking of people who use your pots. I use a lot of earthenware in my kitchen, I wouldn’t expect someone buying my work to deal with that, so I don’t sell anything unless it’s non-absorbent. The issues are strength, absorption, and glaze fit (which really goes back to the first two). The solutions are finding/making a clay body that works and then glazes that fit it. 

Looks like Lemon Grove is in southern CA, near the Mexico border.  (If you google it you can actually see the storefront.)
It appears to be located near a place called Plaster City. (A site producing plaster for USG.)
Imagine setting up a mold making studio in Plaster City?

When looking for glaze recipes (cone 5/6), I chose from sources that included notes (results, application, and test results an extra plus!).
If starting over, would definitely consider refining a (one, just one!) base glaze first, then coloring it.

For example,
This Forum
digitalfire.com
John Hesselberth's FrogpondPottery.com* (There are three low fire glaze recipes, with notes).
Susan Peterson's book The Craft and Art of Clay
Lakeside Pottery's website includes some glaze recipes**
Another book I'm not remembering just now, will look for it ...not finding it, will try again later
Bill van Gilder's book (I use two or three from his book) Wheel-Thrown Pottery
I was looking for recipes from a known source, where there are usage and/or testing notes included (pictures are nice too)
A well behaved clear liner (there's enough white in mine to show over dark clays) glaze took some time, testing, trial, start-overs, some help, and then aaah. 
It has significant MgO, small amounts of Sodium and Potassium, a dose of Lithium (a little bit makes a difference!), and there's Boron - it melts well - for I work cone 5/6; there's enough Silica and Alumina to make a tough glaze that doesn't run or sag much.
*archived here Tested Glazes | Frog Pond Pottery (archive.org)
**Cone 6 Glaze Recipes | Great Mid Range Pottery Glazes (lakesidepottery.com)

Hi and welcome!
It is possible to get durable ware at earthenware, midfire and high fire temperatures, but there are different considerations at each of those points. I won’t use the term food safe, because it’s a bit of a misnomer, and legally only covers whether or not the glaze has cadmium or lead in it. When we talk about glaze durability, we want to make sure that the clay is fired to a point where it would have less than 1% absorbion, the glaze doesn’t leach anything, isn’t crazed, resists both scratching and cutlery marking, and is easy to clean. 
With earthenware in particular, you have to be mindful of glaze fit, because earthenware clay remains porous when fired to maturity, and many will glaze the piece all over, and use kiln stilts instead of leaving a bare foot. You have to be extra mindful of your glaze chemistry, because the low temperatures tend to mean the fun, pretty glazes can sometimes be prone to scratching because they’re lower in silica and alumina.

I just realized that I never came back to reply, and it's super irritating when people do that...
Anyways, I tried working faster and stirring more vigorously, and the plaster set up as usual. Success!
I didn't know that faster stirring made for stronger plaster, so I'll get out the jiffy mixer next time. (I learned to mix plaster in a community college class, so we might have been stirring by hand because it was more practical for a group of people than taking turns with a jiffy mixer.)
Thanks, all, I really appreciate the advice.

Damn @neilestrick!!!
Best low fire work I’ve seen in a long time. So good I could eat it.
To @Biglou13, bisque anything will tolerate that kind of abuse better than a clay close to maturity. Lots of grog, kyanite, or even spodumene (gotten a bit expensive lately) will help. Unglazed flameware sounds better than any other clay body, but I haven’t tried that.
It can be done in the studio, ordinary clay products that handle the extreme temperature swings of cooking, but that’s far from saying it should be. I’ve made several earthenware pots that survive the stovetop, experimenting with clay formulations and bisque temperatures. Though I used them regularly, the maintenance was unforgiving (mold will not be denied if given a habitat to grow), and sooner or later they will fall apart despite all best practices. You didn’t bring this up, but I would never try to sell such a thing. Too complicated. 
Pottery used for cooking is largely disposable, in places it’s actually used. Manufacturers like Le Creuset and Wiliams-Sonoma create ceramic ware that’s functional in a contemporary kitchen, but they are carefully engineered first world conveniences. If people can afford to use metal they do. 
I’ll confess, I’ve never had better beans than those I cooked in clay pots. I don’t want to discourage anybody, I just think they should know what they’re in for. 

@Biglou13I started seriously making sourdough bread 6 weeks ago. Sooooo much fun.  I took a class and learned what I had been doing wrong!  I use cast iron skillets, aka dutch oven.  I would recommend that as well.  

Hi @Biglou13 A flameware body would be your best bet for this. 500F is pretty hot for a clay dish, especially since you'll be dropping wet, room temp dough onto a hot, flat surface. It's a lot to ask of any clay body besides flameware. The other option is to just buy a cheap cast iron dutch oven on Amazon. It works great, and you don't have to worry about it cracking. My dutch oven is preheating in my oven as I type this! 
My loaf from last week. 25% whole wheat, 80% hydration:

https://www.desertcart.ae/products/425093753
This is the clay I am using.
around 1hr and a half to cool dowm