Callie Beller Diesel

I use a talisman at work, and while it’s great for 10 gallon batches of glaze, it would be wildly impractical in my home studio. The cleanup of the brushes is a pain. 
I have a smaller sieve that sits in a 5 gallon pail at home, and I use a large round sash brush to push the glaze through. It works pretty fast and cleans up very easily. 

As much of the density or mass in a firing comes from the shelves themselves it's often helpful to put the taller pots on the bottom shelf, shorter pots and more shelves in the middle of the kiln and tall again on the top shelf. (assuming it has with just one thermocouple or is a manual kiln)

Density of the load has an effect on the way heat moves in the kiln. Kilns are heated by 3 different forms of heat transfer: Radiant, Conduction, and Convection.  Understanding these will help you to understand the need to pack the kiln consistently. Radiant heat is occurs first in the kiln as the elements radiate heat to heat up the air and the pottery. The pottery on the outer edges will heat up to radiate heat towards the center of the kiln. Please note that while Radiant heat is going on Convection is also occurring in the kiln as air heats up and begins to move to the top of the kiln forcing cooler air downward. Overly tight loads will inhibit the movement of air in the kiln causing areas that do not get air to not reach expected cones. However, as this is going on Conduction, where heat is moving through a solid, is taking place, Conduction is a slower process but it allows the pots to heat up from the outside to the inside, and the kiln from the inside to the outside. This good reason to have proper distance from the kiln to outside walls or other materials that could ignite.
Hope this helps to answer some of you concerns.
 
best,
Pres

Thanks so much for your repl
 
Thanks so much for your help. I think I'll adjust the firing schedule and make sure I pack it evenly! Really appreciate you taking your time to reply

I made a body of sculptures out of porcelain paper clay that were somewhat similar. I was using a translucent cone 6 porcelain and firing to cone 8. To prevent them from collapsing in the kiln I made a rudimentary saggar that I placed them into, then filled the void, as well as the piece, with silica sand. This went about half way up the side, I stabilized the "handles" at the top by rolling up some fiber blanket into a tight tube and running through each loop. For more complex shapes you can use kanthal wire to bind rolls to each other. Make the saggar (maybe armature is a better word?) out of cone 10 raku clay or fire clay so you can reuse them forever. 

Good luck, those pieces look great already.

If it’s one of those ones from Amazon, you may be out of luck entirely. They don’t have a good reputation for replacement parts or service. 
There is, however, and old trick you can use that may save you some searching. Place a sponge against the edge of the wheel head, and it’ll absorb most of the slip that flies off the wheel as you throw. 

Juried exhibitions or invitationals through galleries have never netted me any sales. They can be a nice ego rub, which has its own value, but that value isn’t monetary IME. 
Juried fairs or markets however, are a good thing. Juries can help put together a crowd of compatible artists and quality of work, which helps get it in front of people who are interested in such things. 

The grooves are probably not the issue, and also probably not doing much to prevent warping.
Waster slabs can be very thin, and can even be broken/in pieces, but should fully support the piece on it. It's just something that will shrink with the tile and keep the tile from catching on the kiln shelf. Put some kiln wash or alumina wax on the slab so it doesn't fuse to the clay. Waster slab does not need to be bisque fired.
No guarantee it won't crack in the second low-fire firing, but it's worth a shot if you don't need the durability of cone 5.
It's also possible that your tile is cracking from cooling too quickly, and therefore unevenly, through quartz inversion. You could try a controlled cooling from 1100F down to 850F.

2% cobalt oxide is a lot. Even 2% cobalt carbonate is a lot for most glazes. I would definitely test lower amounts of cobalt and see if you can get away with less.
Most chrome-tin pinks (reds) use about 0.2% chrome, which is very little. I just tested a light pink that only uses 1/10 of that! Vey difficult to weight out for testing!

Nope, trivalent chrome does not convert to hexavalent chrome in glazes.Re zinc chromate, according to Hansen "Chrome in zinc glazes tends to form the stable crystalline compound, zinc chromate (ZnCr2O4). which is brown." from this link. 
I plunked your glaze recipe into the glaze calc program I use but I'm not confident in the accuracy of it since specific types of potash feldspar, talc and china clay aren't mentioned in your recipe. Using generic analysis the formula is on the low side for silica though. I would do a lemon slice test on it and see if the colour changes., also keep a test piece in the dishwasher, if you use one, for a few months then compare that to an unwashed piece.What is really important is to have a stable base to prevent leaching. With colouring oxides, aka transition metals, less is better.
 

As others have already noted, neither zinc oxide nor chrome oxide used in reasonable amounts in a stable glaze are toxic. A different issue arises when both are used together in the same glaze - ugliness abounds. Chrome is supposed to be green when in a glaze that does not contain tin. A combination with tin in the right amounts creates a variety of pinks and reds. Zinc with chrome, however, turns assorted shades of brown, when copious amounts are used. It won't hurt you, but you probably don't want to look at it. Perhaps your glaze recipe doesn't have enough for the adverse color reactions.

Let's not throw the baby out with the bathwater here. The form of chrome used makes all the difference in the world in regards to toxicity.
Potters use chrome oxide, it is insoluble in water and gets bound in the glaze matrix in a balance glaze. It is volatile in the kiln so it can cause a pink blush on tin white glazes. Wear gloves if you get contact dermatitis with it. (it's a good idea to wear gloves whenever handling raw materials and glaze slurries to avoid skin reactions)
We do not use the exceedingly dangerous hexavalent chromium in ceramics. Iron chromate is toxic, stay away from using it.
Zinc oxide fumes from kiln firing shouldn't be breathed in, zinc can become volatile above around 850C/1560F and like all the materials we use in glazes practice good studio hygiene and wear a respirator while handling dry materials. In a glaze it isn't a problem. 
Chrome + tin pinks and reds are perfectly safe, whether in a stain or from the oxides.
 
 
 

Callie, I guess this was the artist behind the music bowls installation CÉLESTE BOURSIER-MOUGENOT | CLINAMEN https://www.ngv.vic.gov.au/exhibition/celeste-boursier-mougenot/ 

Callie, it took me quite some time to find this video that quite closely resembles what you've mentioned https://www.youtube.com/watch?v=ADYkCyQ_aRM If it is, it sure is soothing to the ear. And the calming blues and whites add this meditative aspect to it.
I do think interacting with a piece makes you feel more involved and puts you into this mental space that connects you to the activity, in a way that grounds you to the present moment. If a piece was mechanized in some manner, I guess that would be interesting as well, it could make something inanimate come to life which can be seen as appealing in some ways.

I wish I could remember where this piece was installed, or who made it, but an artist made a whole bunch of thinly trimmed porcelain bowls, and floated them in a pool of water with a gentle current running through it. The bowls rang and sounded like wind chimes when they bumped into each other. It was incredibly soothing. 
My initial inclination for question three is to say that I’d prefer to interact with a piece rather than have a constant sound, but I think that subtle environmental interactions could count towards that. 

Juried exhibitions or invitationals through galleries have never netted me any sales. They can be a nice ego rub, which has its own value, but that value isn’t monetary IME. 
Juried fairs or markets however, are a good thing. Juries can help put together a crowd of compatible artists and quality of work, which helps get it in front of people who are interested in such things. 

I get mine about 10 boxes at a time and stack it outside the studio door. I go through it at a rate that it doesn't have time to dry out. But I also have the luxury of living in the same town where I buy my clay.
 

I prefer to use the term "durable" rather than food safe when talking about glazes. There isn't one agreed upon definition of what makes a glaze "food safe". In North America if a glaze does not contain lead or cadmium it can be labelled food safe. This is a very wide definition and adding something along the lines of what Mayco says "Finishedware producers bear responsibility for food safe testing their ware being sold into commerce." IMHO isn't good enough. Like Callie said Strontium Crystal Magic (SCM) is  fine on the outside of pots where your mouth or food won't be in contact with it.
Re lithium and toxicity, just adding a little bit. Topic of lithium and toxicity has come up in many discussions in many forums etc over the years. My impression of the reading I've done is it might not be an issue for most people but for those on lithium therapy it can be, both in the process of mixing glazes and leaching glazes.  Poison is in the dosage scenario.
With all due respect to Callie I found SCM quite rough, dry and unmelted. You could try it by itself on a test tile and see how you find it but it's a bit of a moot point because it isn't used by itself.  The overload of titanium is what makes the crystals/variegation when layered with other glazes. A good way to get interesting glaze reactions is to layer 2 or more dissimilar glazes, what one glaze lacks or has a surplus of reacts with the other glaze, this often results in interesting visual texture. SCM is loaded with fluxes to react with other glazes, that's part of the reason why it works.
Re silica and glaze durability, having as much silica and alumina in a glaze is one of the ways to ensure a durable glaze.  For cone 6 having at least 2.5 molar of silica is a good starting place, if the glaze can dissolve more then it's a good idea to add it if you are looking for a durable glaze. If you look at the screenshot above in the bottom half of the image you can see the silica is 1.68 so at the bare minimum it is about 1/3 short of where it should be. Overloading a matte glaze can quite often turn it into a gloss glaze  and really oversupplying it can turn it back into a matte and crazed glaze so there are parameters within which to work. 
Another aspect of silica that is often overlooked is the mesh size of the silica being used. When you mix glazes using a 325 mesh size silica more of the silica will likely be dissolved in the glaze than if you use 200 mesh. (not applicable for the SCM)
One more thing is to look at the colouring oxides used. Don't use crazy amounts of colouring/transition oxides, use the least you can to still achieve the effect/colour you are after.
There is a good article on toxicity that includes materials here if it helps.

Toxicity is a whole entire subject by itself. Mostly we have to start with definitions to help clarify. 
Tl;dr, yes you can put this glaze on the outside of a pot and it will be fine. It’s not touching food. It melts fine at cone 6, it’s just a “soft” glaze.
When a raw material is labelled toxic, that means it’s toxic in its current form. Once you put a material into a glaze with other materials and fire it, it becomes another material entirely, with different properties. If you’re using a commericallly mixed glaze that is labelled non-toxic, that means it’s not toxic in the unfired state. (It’s probably not toxic in the fired state either, but you’d have to test it to confirm, and manufacturers can’t say that it is for sure under all circumstances without legal problems. People do weird and unexpected things.)
When we’re talking about glazes, most often the finished glaze is more safe than, say, raw lithium. So potters should be concerned about their own health and safety first, and the end user second. Materials like lithium can be handled safely with sensible studio hygiene practices, and can be beneficial in a lot of good glazes.
When knowledgeable glaze chemists talk about food safety, we aren’t talking about whether a glaze will leach Bad Things (TM) into food. This is a very infrequent scenario outside of lead use, and lead hasn’t been used in most handmade pottery for decades now. But we are thinking about craftsmanship and durability. We’re asking questions like Does this glaze have flaws like crazing or pinholing, that can affect structural integrity or possibly harbour bacteria? Does this glaze scratch, or does it cutlery mark? Does it stain easily? Is it easy to clean? If those problems are solved, leaching is usually a non-issue. 
Re the silica question: You need 3 types of components in the right proportions in a base glaze for durability: silica to form glass, alumina for strength and to make it not run too badly, and different metals that make silica and alumina melt at much lower temperatures than they do by themselves (fluxes). Without enough silica or alumina, or if those things are in the wrong proportions, the glaze may react to acids found in many drinks, bases like in dishwasher detergent, or may scratch or cutlery mark. SCM doesn’t supply enough silica for durability, but the strontium is also a problem.
Within the flux category, there’s a bunch of stuff that’s a good idea to use in combination, because each material has beneficial and undesirable properties, and mixing them can bring out the best (or sometimes worst) of both worlds. For example, sodium is a strong flux, which is needed to bring down the melting temperature of silica and alumina, and is in most glazes. However, it tends to make glazes craze when by itself. But if you mix it with calcium (or barium or strontium or lithium and a few others), you can still get the melting, but less crazing.
The calcium/magnesium/strontium etc group of fluxes also give you different colour responses, or can help create matte effects if the proportions are high enough. One of the drawbacks of using strontium or barium though is that neither is very high on the Moh hardness scale, so if you use too much of it, the resulting glaze can be prone to scratching, staining or other flaws. But it helps create that really cool matte surface because it promotes crystallization, so sometimes creative folks make trade offs. 

Toxicity is a whole entire subject by itself. Mostly we have to start with definitions to help clarify. 
Tl;dr, yes you can put this glaze on the outside of a pot and it will be fine. It’s not touching food. It melts fine at cone 6, it’s just a “soft” glaze.
When a raw material is labelled toxic, that means it’s toxic in its current form. Once you put a material into a glaze with other materials and fire it, it becomes another material entirely, with different properties. If you’re using a commericallly mixed glaze that is labelled non-toxic, that means it’s not toxic in the unfired state. (It’s probably not toxic in the fired state either, but you’d have to test it to confirm, and manufacturers can’t say that it is for sure under all circumstances without legal problems. People do weird and unexpected things.)
When we’re talking about glazes, most often the finished glaze is more safe than, say, raw lithium. So potters should be concerned about their own health and safety first, and the end user second. Materials like lithium can be handled safely with sensible studio hygiene practices, and can be beneficial in a lot of good glazes.
When knowledgeable glaze chemists talk about food safety, we aren’t talking about whether a glaze will leach Bad Things (TM) into food. This is a very infrequent scenario outside of lead use, and lead hasn’t been used in most handmade pottery for decades now. But we are thinking about craftsmanship and durability. We’re asking questions like Does this glaze have flaws like crazing or pinholing, that can affect structural integrity or possibly harbour bacteria? Does this glaze scratch, or does it cutlery mark? Does it stain easily? Is it easy to clean? If those problems are solved, leaching is usually a non-issue. 
Re the silica question: You need 3 types of components in the right proportions in a base glaze for durability: silica to form glass, alumina for strength and to make it not run too badly, and different metals that make silica and alumina melt at much lower temperatures than they do by themselves (fluxes). Without enough silica or alumina, or if those things are in the wrong proportions, the glaze may react to acids found in many drinks, bases like in dishwasher detergent, or may scratch or cutlery mark. SCM doesn’t supply enough silica for durability, but the strontium is also a problem.
Within the flux category, there’s a bunch of stuff that’s a good idea to use in combination, because each material has beneficial and undesirable properties, and mixing them can bring out the best (or sometimes worst) of both worlds. For example, sodium is a strong flux, which is needed to bring down the melting temperature of silica and alumina, and is in most glazes. However, it tends to make glazes craze when by itself. But if you mix it with calcium (or barium or strontium or lithium and a few others), you can still get the melting, but less crazing.
The calcium/magnesium/strontium etc group of fluxes also give you different colour responses, or can help create matte effects if the proportions are high enough. One of the drawbacks of using strontium or barium though is that neither is very high on the Moh hardness scale, so if you use too much of it, the resulting glaze can be prone to scratching, staining or other flaws. But it helps create that really cool matte surface because it promotes crystallization, so sometimes creative folks make trade offs. 

I wish I could remember where this piece was installed, or who made it, but an artist made a whole bunch of thinly trimmed porcelain bowls, and floated them in a pool of water with a gentle current running through it. The bowls rang and sounded like wind chimes when they bumped into each other. It was incredibly soothing. 
My initial inclination for question three is to say that I’d prefer to interact with a piece rather than have a constant sound, but I think that subtle environmental interactions could count towards that. 

It’s worth noting that Etsy selling has never been a way for most users to make a full time living, but many do use it as a supplement or as one of many income streams. Also, don’t follow their advice on pricing your work. Because of how they structure their fees, you’ll have to start with your base price and add all the assorted percentages they charge. Use caution when using their forum for advice on running a business there. Many of the seller communities labour under the (incorrect) assumption that high prices will drive away customers, and that you have to have frequent sales and discounts. None of that is true. Cheap prices draw in deal hunters who will not treat you well. 

Juried exhibitions or invitationals through galleries have never netted me any sales. They can be a nice ego rub, which has its own value, but that value isn’t monetary IME. 
Juried fairs or markets however, are a good thing. Juries can help put together a crowd of compatible artists and quality of work, which helps get it in front of people who are interested in such things. 

I wish I could remember where this piece was installed, or who made it, but an artist made a whole bunch of thinly trimmed porcelain bowls, and floated them in a pool of water with a gentle current running through it. The bowls rang and sounded like wind chimes when they bumped into each other. It was incredibly soothing. 
My initial inclination for question three is to say that I’d prefer to interact with a piece rather than have a constant sound, but I think that subtle environmental interactions could count towards that. 

Toxicity is a whole entire subject by itself. Mostly we have to start with definitions to help clarify. 
Tl;dr, yes you can put this glaze on the outside of a pot and it will be fine. It’s not touching food. It melts fine at cone 6, it’s just a “soft” glaze.
When a raw material is labelled toxic, that means it’s toxic in its current form. Once you put a material into a glaze with other materials and fire it, it becomes another material entirely, with different properties. If you’re using a commericallly mixed glaze that is labelled non-toxic, that means it’s not toxic in the unfired state. (It’s probably not toxic in the fired state either, but you’d have to test it to confirm, and manufacturers can’t say that it is for sure under all circumstances without legal problems. People do weird and unexpected things.)
When we’re talking about glazes, most often the finished glaze is more safe than, say, raw lithium. So potters should be concerned about their own health and safety first, and the end user second. Materials like lithium can be handled safely with sensible studio hygiene practices, and can be beneficial in a lot of good glazes.
When knowledgeable glaze chemists talk about food safety, we aren’t talking about whether a glaze will leach Bad Things (TM) into food. This is a very infrequent scenario outside of lead use, and lead hasn’t been used in most handmade pottery for decades now. But we are thinking about craftsmanship and durability. We’re asking questions like Does this glaze have flaws like crazing or pinholing, that can affect structural integrity or possibly harbour bacteria? Does this glaze scratch, or does it cutlery mark? Does it stain easily? Is it easy to clean? If those problems are solved, leaching is usually a non-issue. 
Re the silica question: You need 3 types of components in the right proportions in a base glaze for durability: silica to form glass, alumina for strength and to make it not run too badly, and different metals that make silica and alumina melt at much lower temperatures than they do by themselves (fluxes). Without enough silica or alumina, or if those things are in the wrong proportions, the glaze may react to acids found in many drinks, bases like in dishwasher detergent, or may scratch or cutlery mark. SCM doesn’t supply enough silica for durability, but the strontium is also a problem.
Within the flux category, there’s a bunch of stuff that’s a good idea to use in combination, because each material has beneficial and undesirable properties, and mixing them can bring out the best (or sometimes worst) of both worlds. For example, sodium is a strong flux, which is needed to bring down the melting temperature of silica and alumina, and is in most glazes. However, it tends to make glazes craze when by itself. But if you mix it with calcium (or barium or strontium or lithium and a few others), you can still get the melting, but less crazing.
The calcium/magnesium/strontium etc group of fluxes also give you different colour responses, or can help create matte effects if the proportions are high enough. One of the drawbacks of using strontium or barium though is that neither is very high on the Moh hardness scale, so if you use too much of it, the resulting glaze can be prone to scratching, staining or other flaws. But it helps create that really cool matte surface because it promotes crystallization, so sometimes creative folks make trade offs.