Callie Beller Diesel

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. 

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. 

There are several potters who show their seams on mugs and bowls. I can't think of names off of the top of my head, but I follow a few on Instagram. Saying that you copied the seam is like saying that you copied the shape of a mug. 
Betty

Copying a design versus using the same technique while making a pot are two different things. Are there any new designs in functional ware that haven't been done before by someone somewhere, I don't know but I sort of doubt it.
I have noticed quite a few makers doing exactly what you describe; leaving the mark of the making process visible at the joins. I don't think you need to waste your energy trying to justify your work. Getting inspiration from others work is one way to challenge yourself into making new forms, and making them your own.  I'm sorry you are going through this, it must have been upsetting to you.

No worries on firing when it's 40F outside.
If the glaze crazes when you remove pots from the kiln it won't be because of the temperature being a little cold. It will be because the glaze is too small for the clay. Simple way to think of this is to think of a pair of jeans and how they fit. If I wear a size 10 and my daughter wears a size 4 if I put her jeans on the seams will split. If she puts my jeans on they will bag out and fall off. Tight splitting jeans is like a crazing glaze, loose falling off jeans is like shivering glaze. Crazing is far far more common than shivering. 

I think that since so many of us fire to midrange the go to mindset is bisque low, fire higher to glaze. Problem with this when working with earthenware is more often than not the commercial glazes are rated in the 06-04 range yet many earthenware bodies will actually mature higher than this and still be porous enough to take glaze well. I haven't used the body in question, but if it can go to 02 (as the lit suggests) then I would at least try 03 and see how it does. 

Just heard this -The owner of Kemper Tools has sold the business. New owner has to move the factory as the property has sold as well. Not sure if this will stay  as a domestic business and what will be made  in terms of the tool line. They made so many I would not be surprized that that line is trimmed down . Pricing may change as well.. It's funny as I noticed Bailey has a sale going on Kemper now which is odd. My guess is there will be a time period that these tools will not be in production as well. The good news is Kemper will be around in some sense in the future. 

@Katie S I have become quite adamant about "what clay is it?"  Name, rank, serial number, when firing for others.  If they do not know, I politely decline.  A friend of mine just had a horrible kiln accident with that very thing.  Melted cups and plates all over the shelves.  Yes, they were low fire.  Fired to mid fire.  The person making the request didn't do their work.  You would probably be fine with 04,  probably.  But.....

Chiming in a little late on this one, but you mentioned the crack in your piece happening at another studio, where the bisque cycle is unknown to you. I strongly suspect the cause wasn’t the fact that it was bisqued twice, more that the cycle used was likely not suitable for your piece. Two foot pieces are going to need a slower cycle than regular pieces, just due to sheer thermal mass.  If the studio’s usual bisque cycle didn’t take that into account, or the kiln pack wasn’t a particularly heavy or even, that would be the most likely explanation to me.
Side note: I just spent the morning going through Ceramic Materials Workshop’s new commercial clay body analysis resource. It’s free if anyone wants to check it out for themselves. So far the submissions are limited to assorted clays in the US that are in the roughly cone 6-10 range. Bill’s statement that clays will shrink upon a second bisque depend greatly on what the first bisque temperature was, and which clay body is in question. If you’re bisquing to a common 06 temperature, the statement of a less than 1% increase is likely enough. If your usual bisque is higher or lower, it might not be. After about 1000*C (roughly cone 04) many clay bodies hold steady for a time before continuing to shrink. If you bisque very low to cone 020, the shrinkage charts actually decrease for a time, meaning the piece expands a bit after the carbonates and chemical water burn off. 
Again, this is VERY clay body dependent. 
 
 
 

Now, to give you a sense of what 'curio' scale means here is the same bisque shown in my hand.  Here I have airbrushed on underglaze in greys and black and I am now dappling him.  Once fired with a clear glaze over this underglaze, he will be a dappled grey!  This is a sales piece that I will be offering at auction probably next weekend while I'm at a live show event.  But for now there's a lot of work to do to him to get him ready to be the new sample of my sculpture in ceramic!  I'll post more photos as I go so you all can see the finished boy when he's done.  I work in many layers, fire a number of times, and will also work in over glazes.  The upright mane ribbons will be added later after he's completed and are going to be enameled metal but I haven't finished making them yet.  They each fit down into little  holes I have drilled down his neck.
I am also making mold pieces for a larger 'traditional' scale version of this boy that stands about 8 inches tall.  I hope to have that one casting by June in time for a huge international event I'm attending in July at the Kentucky Horse Park in Lexington, KY.

This is Porths, my first version of this sculpture I started way back about 2007, almost completed in 2009 before illness derailed my studio for a while.  At any rate, I FINALLY finished this boy last year and released him in a resin edition.  I've since gone on to do a 'hairy' Pasture Porthos who's a bit chunkier, and with more feather, thicker legs, long mane and swishy Fabio tail who's casting in a resin edition this year.
Anyway, I've been busting butt to make MOLDS for these two versions of my Porthos sculpture.  Currently I am having the hairy Pasture Porthos molded and cast in England in fine bone china, though I'm also about to start testing slip and settlers for fine bone china pieces here in my studio later this year.  Meanwhile I'm focusing first on using finely ball milled earthenware with talc to cast some pieces.  This first one I've molded right here in studio is what we call Curio scale, a large mini in size.  He's my test cast to see if my mold worked (it did first try!) and to help me figure out how I want to rework and clean up my mold pieces to work even better.  Then I'll be making rubber molds starting next week of each plaster mold piece so I'll have a master from which to cast as many plaster replacement molds as I ever will want, later.
So here's my first ceramic bisque of Porthos with his original docked tail version (mane flights to be added later), an American Percheron with tail bows.

two layers of 1/2” Hardibacker board will give you some peace. No mixing plaster, woohoo! Great to wedge on, dimensionally satble, easy to get. I still use it for wedging and working surfaces, as well as ware boards. Pulls water out aggressively. It will saturate eventually, the same issue happens to terra cotta planter plates which I also use for small batches. Of course it happens with plaster too, 

This. 100000X this. If your clay body is giving pinholes of some kind with several glazes, it’s the clay body, not the glaze or the assorted firing cycles. It may well be that an ingredient in the Laguna body just doesn’t want to play nice, whatever is done with it. You have to weigh wether you like using this clay more than you want a perfectly defect free surface.
If you need a good red clay/white glaze combo, M390 and Ravenscrag slip 80/20  with frit 3134, and 2 opacifiers of your choice. (I recommend a tin and zircopax combo if you don’t want any titanium variegation). Reasoning: they give different qualities of white. Tin by itself is very soft, and can be grey-ish or even drift towards a violet in certain light when used on M390 in particular. It’s also expensive. Zircopax by itself is very stark, and gives a very “bathroom fixture” white that resists breaking or pooling. The 2 together give a soft white without weird tonal casts, gives a little more visual interest and offsets the end price of the glaze. I use a max of 10% opacifier, but judging from the look of your photos, you might want a slightly more translucent version, so you could see what happens with 7 or 8%. 
I fire with a very analog kiln at home, so I can’t give specific numbers on ramps and speed. I slow my kiln down around the carbon burnout stages mentioned in the Steve Davis article, and I judge that through the colour of the kiln. I’ve recently started working at a place that has brand new Bartlett 2 touchscreens though. I feel spoiled! They are to be preferred over my methods.
I think speed of bisque is more important than end temperature, so slow through the appropriate zones. I think the Naomi Clement one is a bit of overkill.  The 12-14 hours of Davis’s cycle (assuming no drying soak at the beginning) is plenty long. Note the pauses around 1500F that both Clement and Hulk have suggested.
The glaze cycle I use to get what is effectively cone 7 is a drop and hold, similar to what you’ve already worked out. I go to cone 6 with a 20 minute hold after the drop.
Note that there will be upcoming changes to M390: according to my supplier, Plainsman demand has gone through the roof lately, and they’re struggling to keep up. They have one clay mixer that they have to cycle all their different clay bodies through from lightest to darkest. While another one has been ordered, it’s not expected in until next year. In the meantime, they’ve made the decision to remove the 80 mesh sieve from the machinery in order to get the clay to go through faster. This will affect M390’s texture starting this year. So we’ll all have to revise some porosity testing until they get the new machinery in place.
 
The last suggestion I would have is another bisque cycle. But this time, only go to 010. There have been a few reliable potters in various internet spaces lately speaking about this (For Flux Sake podcast in particular). I believe the argument is that the application a more porous clay body gives a dipped glaze results in fewer defects. I haven’t experimented with this personally though, so that one is a shot in the dark if nothing else works.

This. 100000X this. If your clay body is giving pinholes of some kind with several glazes, it’s the clay body, not the glaze or the assorted firing cycles. It may well be that an ingredient in the Laguna body just doesn’t want to play nice, whatever is done with it. You have to weigh wether you like using this clay more than you want a perfectly defect free surface.
If you need a good red clay/white glaze combo, M390 and Ravenscrag slip 80/20  with frit 3134, and 2 opacifiers of your choice. (I recommend a tin and zircopax combo if you don’t want any titanium variegation). Reasoning: they give different qualities of white. Tin by itself is very soft, and can be grey-ish or even drift towards a violet in certain light when used on M390 in particular. It’s also expensive. Zircopax by itself is very stark, and gives a very “bathroom fixture” white that resists breaking or pooling. The 2 together give a soft white without weird tonal casts, gives a little more visual interest and offsets the end price of the glaze. I use a max of 10% opacifier, but judging from the look of your photos, you might want a slightly more translucent version, so you could see what happens with 7 or 8%. 
I fire with a very analog kiln at home, so I can’t give specific numbers on ramps and speed. I slow my kiln down around the carbon burnout stages mentioned in the Steve Davis article, and I judge that through the colour of the kiln. I’ve recently started working at a place that has brand new Bartlett 2 touchscreens though. I feel spoiled! They are to be preferred over my methods.
I think speed of bisque is more important than end temperature, so slow through the appropriate zones. I think the Naomi Clement one is a bit of overkill.  The 12-14 hours of Davis’s cycle (assuming no drying soak at the beginning) is plenty long. Note the pauses around 1500F that both Clement and Hulk have suggested.
The glaze cycle I use to get what is effectively cone 7 is a drop and hold, similar to what you’ve already worked out. I go to cone 6 with a 20 minute hold after the drop.
Note that there will be upcoming changes to M390: according to my supplier, Plainsman demand has gone through the roof lately, and they’re struggling to keep up. They have one clay mixer that they have to cycle all their different clay bodies through from lightest to darkest. While another one has been ordered, it’s not expected in until next year. In the meantime, they’ve made the decision to remove the 80 mesh sieve from the machinery in order to get the clay to go through faster. This will affect M390’s texture starting this year. So we’ll all have to revise some porosity testing until they get the new machinery in place.
 
The last suggestion I would have is another bisque cycle. But this time, only go to 010. There have been a few reliable potters in various internet spaces lately speaking about this (For Flux Sake podcast in particular). I believe the argument is that the application a more porous clay body gives a dipped glaze results in fewer defects. I haven’t experimented with this personally though, so that one is a shot in the dark if nothing else works.

Tagging @Callie Beller Diesel on this in case I'm misremembering but I believe she fires 390 to cone 7 for absorption reasons.

Be sure to carefully check for application defects!
This may be what was nagging at my memory?
During yesterday's glaze session, while checking for tiny bubble marks and pinholes, an "ooh yeaa" moment:
microtips - Studio Operations and Making Work - Ceramic Arts Daily Community
Where any air can be trapped in the clay, or at the edge of applied underglaze, or at the edge of wax resist, et cetera, as the glaze dries, then the bubble pops - there's a pinhole!
I'm checking the glaze layers more carefully than ever!