High Bridge Pottery

Kaolin should reduce drying time quite a bit, but it will probably increase the porosity, too. Personally, I would be very interested in seeing a body that was all kaolin/no ball clay, to see how much the color of the body is affected.
As a kiln tech guy, the most exciting part about this is the potential for really good element life and kiln lifespan while still making vitrified ware. It's something I've though about a lot, but never had the time to pursue. It would be really bad for my kiln sales and repair business, though! I used to fire at cone 8, and by dropping to cone 6, which is only a difference of about 50 degrees, my element life increased by 25-30%. By dropping from cone 6 to even cone 1 would make a huge difference. This is exactly what clay and glaze manufacturers should be working on as energy costs and kiln costs continue to rise. On that note, why cone 03? Is that the limit of your kiln? Have you though about taking one of your tests that is at around 2.5% absorption and going 1-2 cones hotter to see what happens?
I'm also excited to see how glaze fit works in these bodies when you get to that point. I have to think you'll get a much better clay/glaze interface than with typical porous earthenware bodies.

Thank you  a bit of method and a bit of madness  I enjoy sharing what I am learning and always learn a lot from people on here. Nobody in real life wants to listen to me talk ceramics
I think the small particles size in the Hymod is good for low porosity but bad for low drying times.
There is test 72 that has 65 Hymod, 5 Frit and 30 Nepheline Syenite that has 2.78% absorption so I would think having 10% frit instead should be around 1-1.5% absorption. I will run a test and see if the theory works.
It's interesting that 76 with 32.5 hymod 32.5 kentucky 5 frit and 30 Nepheline Syenite has 2.09% absorption. I wonder what is happening there, a little more silica and less alumina in 76 but not that different.

 
I was hoping the Nepheline Syenite would do a bit more melting. I have a few more tests drying adding Petalite and Dolomite with 20-30% Nepheline Syenite and 5% frit so hopefully one of those will be lower than 1.5%
I did think ball clay comes with extra silica so I might not have to add any. There's no real way of telling what CTE the clay will be. It's funny that you add silica to clay to increase expansion but add it to glazes to decrease expansion.

I appreciate your methodical approach. I rarely use unity, it is certainly useful though. For me it tends to serve as a reality check or troubleshooting aid. I’m a long way from mastering that tool, but glad it’s in my toolbox. Your picture above is a nice illustration, two mixtures with similar chemistry behaving very differently. 
My armchair reasoning is you’ve got the issues of: Hymod clay really holding on to water, trying to get the clay vitreous using as little frit as possible, and using materials that are readily available and not too expensive.
I’ll throw in some thoughts from my perspective, for fun. Between b0073 and b0010, I feel like 73 doesn’t have enough frit to make the neph sy go into melt. 10 has too much plastic material to dry at a reasonable speed (I am amazed that one got so tight with just 20% frit though! Powerful stuff.) I jumped to figuring how to split the difference in a useful way (60 ball clay, 30 neph sy, and 10 frit was where my brain landed). 
 I feel the same way about introducing silica as an additional ingredient, getting the body to play right then tuning glaze and/or body if there are problems with fit. All your materials have significant silica built in.
Anyway, I enjoy you giving us this window to watch the journey unfold, I’m learning a lot. 

Electric at .5 £/kwh is about $0.61 (US dollars), wow.
In Central California, off-peak Winter is just over $0.28/kwh (was 34¢ in Summer).
HBP, do the graphs depict percent absorption (water) by weight (vertical) for each trial (horizontal)?
If so, that's some good results!
I went with petalite (to lower liner glaze COE), cheaper per unit lithium (and avoiding the reported Spodumene foaming). Am seeing some small grey specks, but I don't mind them.


 

Have some interesting results from my Calcium, Magnesium and Lithium experiments. Might have to swap the Spodumene for Petalite as it is cheaper but I had both lying around and went for Spodumene.
These tests took about 80 hours to dry Starting mix is 20g dry ingredients and 13-15g water. Need to run more tests adding other clays and feldspars to reduce drying time.
 
There seems to be a Calcium and Magnesium sweet spot where too little or too much makes it more porous. The Lithium just seems to reduce porosity.
 
All tests with 5% frit but I have tried to annotate the graphs and reorganise tests as my numberings went a bit all over the place as I came up with ideas. I ran a pure ball clay sample and added the 5% and 10% frit  data from last time to the left of the chart for comparison.
 
These didn't actually make it to cone 03 and much more like cone 04. Cone 03 made it to about the 2-3 o'clock position so need an extra 10 min hold on the next firing.

 
Another graph of some 5% Spodumene 5% Frit + extras

Thank you so much for sharing this.  I am continually drawn to low fire bodies and processes. 

I felt like the OP was more of the opinion that even if you provide a warning is there really any need to share them so I felt it was a bit mean to blame the glazy user when everybody does it.
 
It's good to provide the warning but that doesn't always transfer with the recipe. I think it should be down to the end user to understand what they are dealing with but a lot of people may see a glaze they like and breath through their nose as an extra precaution.

I am not exactly sure this is the recipe they are trying to create but when places like here publish a recipe with 45% Manganese as  "some of our favorite cone 6 glaze recipes in a convenient recipe-card format, perfect for printing and taking to the pottery studio"  you can't really blame them.
https://ceramicartsnetwork.org/freebies/guide/15-tried-and-true-cone-6-glaze-recipes

You can get reasonable results using laser printer, underglaze/oxide mixed with linseed oil and a gum arabic solution.
 

You can get reasonable results using laser printer, underglaze/oxide mixed with linseed oil and a gum arabic solution.
 

You can get reasonable results using laser printer, underglaze/oxide mixed with linseed oil and a gum arabic solution.
 

I felt like the OP was more of the opinion that even if you provide a warning is there really any need to share them so I felt it was a bit mean to blame the glazy user when everybody does it.
 
It's good to provide the warning but that doesn't always transfer with the recipe. I think it should be down to the end user to understand what they are dealing with but a lot of people may see a glaze they like and breath through their nose as an extra precaution.

Fantastic! Thank you for sharing your work. Vitreous ware at low fire temperatures seems like a magical frontier to me, I’m delighted to see your discoveries. 

I have always wanted to experiment with fritware and only having access to a small kiln that struggles to reach top temperatures I thought it may be worth trying out.
 
First some vague calculations to see if it makes sense.
I think electricity prices in the UK are pretty extortionate right now at £0.30-£0.60p a kwh. My kiln takes at least an extra 2.5h to get from 1100c to 1260c+ and at 3kwh * 0.40p * 2.5h = £3 extra a firing if I am getting a "good price" on electricity
Clay can cost anywhere from £0.40 per kg to £1.30 per kg and I am assuming around 25% of that is water. A powdered stoneware costs about £1.50 a kg so lets call it £1 a kg for a ballpark figure buying 100-250kg a go.
I could fit maybe 10 mugs in my kiln at say 450g a mug so total clay cost would be £4.50, with the extra £3 a firing that means I can 'break even' with a fritware body costing £1.66 a kg. A Larger kiln should work out more efficient on energy I think so less extra cost.
 
I have two ball clays and a kaolin kicking around so after reading kaolin can take up to 30% frit I decided to start with the ball clays. Hyplas 71 and Hymod AT at £0.90 per kg (25kg bags). Not sure I am in the power or fiberglass industry but they sell it at pottery suppliers

 
Next are the frits that run from £6-10 a kg (25kg bags). I think they are pretty expensive in the UK.
I went with an Alkaline Frit (similar to 3110 but cheaper) and Ferro Frit 3124, 3134 and 3195 for the glaze and to try in the body.
 
At 5% frit to ball clay it will cost £1.16-1.31 per kg.
At 10% frit to ball clay it will cost £1.41-1.73 per kg.
At 20% frit to ball clay it will cost £1.93-2.56 per kg.
 
Looking at that I thought it was definitely worth trying as I could possibly get it under £1.66 a kg. I guess I need to factor in my time making the clay into the cost but if I am planning on casting I feel it would be similar anyway to making a stoneware slip.
I tested each ball clay with 5, 10, 13, 16 and 20% frit in the order Alkaline, 3124, 3134 and 3195. The last 4 tests have a 50/50 mix ball clay to kaolin and 20% of each frit. Fired to cone 03 and then boiled for 5 hours to get the absorption values.
The results actually came out better than I expected with Hymod ball clay and 10% alkaline frit getting to 0.5% absorption at £1.41 per kg I think B0011 I must have messed up as the data doesn't fit.
 
 
Colours are sort of accurate in this photo, not a very good camera on my phone.

 
Now I am experimenting with adding different Calcium Magnesium and Lithium fluxes to see what happens.
Reading that I could have issues with drying times using pure ball clay. It's interesting that the Hyplas has larger particles than Hymod but it is sold as the more plastic, maybe there's something I am missing.
Never did any working out for how much more the glaze costs so maybe that will make things look worse but hopefully it is such a small % total it doesn't make much difference.

I have always wanted to experiment with fritware and only having access to a small kiln that struggles to reach top temperatures I thought it may be worth trying out.
 
First some vague calculations to see if it makes sense.
I think electricity prices in the UK are pretty extortionate right now at £0.30-£0.60p a kwh. My kiln takes at least an extra 2.5h to get from 1100c to 1260c+ and at 3kwh * 0.40p * 2.5h = £3 extra a firing if I am getting a "good price" on electricity
Clay can cost anywhere from £0.40 per kg to £1.30 per kg and I am assuming around 25% of that is water. A powdered stoneware costs about £1.50 a kg so lets call it £1 a kg for a ballpark figure buying 100-250kg a go.
I could fit maybe 10 mugs in my kiln at say 450g a mug so total clay cost would be £4.50, with the extra £3 a firing that means I can 'break even' with a fritware body costing £1.66 a kg. A Larger kiln should work out more efficient on energy I think so less extra cost.
 
I have two ball clays and a kaolin kicking around so after reading kaolin can take up to 30% frit I decided to start with the ball clays. Hyplas 71 and Hymod AT at £0.90 per kg (25kg bags). Not sure I am in the power or fiberglass industry but they sell it at pottery suppliers

 
Next are the frits that run from £6-10 a kg (25kg bags). I think they are pretty expensive in the UK.
I went with an Alkaline Frit (similar to 3110 but cheaper) and Ferro Frit 3124, 3134 and 3195 for the glaze and to try in the body.
 
At 5% frit to ball clay it will cost £1.16-1.31 per kg.
At 10% frit to ball clay it will cost £1.41-1.73 per kg.
At 20% frit to ball clay it will cost £1.93-2.56 per kg.
 
Looking at that I thought it was definitely worth trying as I could possibly get it under £1.66 a kg. I guess I need to factor in my time making the clay into the cost but if I am planning on casting I feel it would be similar anyway to making a stoneware slip.
I tested each ball clay with 5, 10, 13, 16 and 20% frit in the order Alkaline, 3124, 3134 and 3195. The last 4 tests have a 50/50 mix ball clay to kaolin and 20% of each frit. Fired to cone 03 and then boiled for 5 hours to get the absorption values.
The results actually came out better than I expected with Hymod ball clay and 10% alkaline frit getting to 0.5% absorption at £1.41 per kg I think B0011 I must have messed up as the data doesn't fit.
 
 
Colours are sort of accurate in this photo, not a very good camera on my phone.

 
Now I am experimenting with adding different Calcium Magnesium and Lithium fluxes to see what happens.
Reading that I could have issues with drying times using pure ball clay. It's interesting that the Hyplas has larger particles than Hymod but it is sold as the more plastic, maybe there's something I am missing.
Never did any working out for how much more the glaze costs so maybe that will make things look worse but hopefully it is such a small % total it doesn't make much difference.

Years back I did a 1/3 kaolin. 1/3 frit 3110, and the balance in silica and ball clay. Fired to cone 04 as I recall; very low absorption. It is very doable, and 1.5% absorption is well within reason. Enjoy the journey.
Tom

Very interesting! Thank you for sharing. I'd shoot for below 1.5%. 3% will probably still weep. I agree, try some kaolin. It should speed up drying and increase whiteness. Have you done any tests to figure out how low you'll have to bisque fire in order to get suitable porosity for glazing?

Just curious if you considered using a red earthenware and adding frit to that? From Hansen's Zero 3 page he speaks of needing 5% frit added to his earthenware to make it vitreous. Given that the frit is the expensive part of the mix it might be worth testing if you are okay with an earthenware colour. There is an earthenware available here that when fired to cone 04 has porosity at 6.0% but when fired to cone 02 porosity goes down to 1.5%,  anything like that where you live?
Nice experiment work!

I have always wanted to experiment with fritware and only having access to a small kiln that struggles to reach top temperatures I thought it may be worth trying out.
 
First some vague calculations to see if it makes sense.
I think electricity prices in the UK are pretty extortionate right now at £0.30-£0.60p a kwh. My kiln takes at least an extra 2.5h to get from 1100c to 1260c+ and at 3kwh * 0.40p * 2.5h = £3 extra a firing if I am getting a "good price" on electricity
Clay can cost anywhere from £0.40 per kg to £1.30 per kg and I am assuming around 25% of that is water. A powdered stoneware costs about £1.50 a kg so lets call it £1 a kg for a ballpark figure buying 100-250kg a go.
I could fit maybe 10 mugs in my kiln at say 450g a mug so total clay cost would be £4.50, with the extra £3 a firing that means I can 'break even' with a fritware body costing £1.66 a kg. A Larger kiln should work out more efficient on energy I think so less extra cost.
 
I have two ball clays and a kaolin kicking around so after reading kaolin can take up to 30% frit I decided to start with the ball clays. Hyplas 71 and Hymod AT at £0.90 per kg (25kg bags). Not sure I am in the power or fiberglass industry but they sell it at pottery suppliers

 
Next are the frits that run from £6-10 a kg (25kg bags). I think they are pretty expensive in the UK.
I went with an Alkaline Frit (similar to 3110 but cheaper) and Ferro Frit 3124, 3134 and 3195 for the glaze and to try in the body.
 
At 5% frit to ball clay it will cost £1.16-1.31 per kg.
At 10% frit to ball clay it will cost £1.41-1.73 per kg.
At 20% frit to ball clay it will cost £1.93-2.56 per kg.
 
Looking at that I thought it was definitely worth trying as I could possibly get it under £1.66 a kg. I guess I need to factor in my time making the clay into the cost but if I am planning on casting I feel it would be similar anyway to making a stoneware slip.
I tested each ball clay with 5, 10, 13, 16 and 20% frit in the order Alkaline, 3124, 3134 and 3195. The last 4 tests have a 50/50 mix ball clay to kaolin and 20% of each frit. Fired to cone 03 and then boiled for 5 hours to get the absorption values.
The results actually came out better than I expected with Hymod ball clay and 10% alkaline frit getting to 0.5% absorption at £1.41 per kg I think B0011 I must have messed up as the data doesn't fit.
 
 
Colours are sort of accurate in this photo, not a very good camera on my phone.

 
Now I am experimenting with adding different Calcium Magnesium and Lithium fluxes to see what happens.
Reading that I could have issues with drying times using pure ball clay. It's interesting that the Hyplas has larger particles than Hymod but it is sold as the more plastic, maybe there's something I am missing.
Never did any working out for how much more the glaze costs so maybe that will make things look worse but hopefully it is such a small % total it doesn't make much difference.

I have always wanted to experiment with fritware and only having access to a small kiln that struggles to reach top temperatures I thought it may be worth trying out.
 
First some vague calculations to see if it makes sense.
I think electricity prices in the UK are pretty extortionate right now at £0.30-£0.60p a kwh. My kiln takes at least an extra 2.5h to get from 1100c to 1260c+ and at 3kwh * 0.40p * 2.5h = £3 extra a firing if I am getting a "good price" on electricity
Clay can cost anywhere from £0.40 per kg to £1.30 per kg and I am assuming around 25% of that is water. A powdered stoneware costs about £1.50 a kg so lets call it £1 a kg for a ballpark figure buying 100-250kg a go.
I could fit maybe 10 mugs in my kiln at say 450g a mug so total clay cost would be £4.50, with the extra £3 a firing that means I can 'break even' with a fritware body costing £1.66 a kg. A Larger kiln should work out more efficient on energy I think so less extra cost.
 
I have two ball clays and a kaolin kicking around so after reading kaolin can take up to 30% frit I decided to start with the ball clays. Hyplas 71 and Hymod AT at £0.90 per kg (25kg bags). Not sure I am in the power or fiberglass industry but they sell it at pottery suppliers

 
Next are the frits that run from £6-10 a kg (25kg bags). I think they are pretty expensive in the UK.
I went with an Alkaline Frit (similar to 3110 but cheaper) and Ferro Frit 3124, 3134 and 3195 for the glaze and to try in the body.
 
At 5% frit to ball clay it will cost £1.16-1.31 per kg.
At 10% frit to ball clay it will cost £1.41-1.73 per kg.
At 20% frit to ball clay it will cost £1.93-2.56 per kg.
 
Looking at that I thought it was definitely worth trying as I could possibly get it under £1.66 a kg. I guess I need to factor in my time making the clay into the cost but if I am planning on casting I feel it would be similar anyway to making a stoneware slip.
I tested each ball clay with 5, 10, 13, 16 and 20% frit in the order Alkaline, 3124, 3134 and 3195. The last 4 tests have a 50/50 mix ball clay to kaolin and 20% of each frit. Fired to cone 03 and then boiled for 5 hours to get the absorption values.
The results actually came out better than I expected with Hymod ball clay and 10% alkaline frit getting to 0.5% absorption at £1.41 per kg I think B0011 I must have messed up as the data doesn't fit.
 
 
Colours are sort of accurate in this photo, not a very good camera on my phone.

 
Now I am experimenting with adding different Calcium Magnesium and Lithium fluxes to see what happens.
Reading that I could have issues with drying times using pure ball clay. It's interesting that the Hyplas has larger particles than Hymod but it is sold as the more plastic, maybe there's something I am missing.
Never did any working out for how much more the glaze costs so maybe that will make things look worse but hopefully it is such a small % total it doesn't make much difference.

I have always wanted to experiment with fritware and only having access to a small kiln that struggles to reach top temperatures I thought it may be worth trying out.
 
First some vague calculations to see if it makes sense.
I think electricity prices in the UK are pretty extortionate right now at £0.30-£0.60p a kwh. My kiln takes at least an extra 2.5h to get from 1100c to 1260c+ and at 3kwh * 0.40p * 2.5h = £3 extra a firing if I am getting a "good price" on electricity
Clay can cost anywhere from £0.40 per kg to £1.30 per kg and I am assuming around 25% of that is water. A powdered stoneware costs about £1.50 a kg so lets call it £1 a kg for a ballpark figure buying 100-250kg a go.
I could fit maybe 10 mugs in my kiln at say 450g a mug so total clay cost would be £4.50, with the extra £3 a firing that means I can 'break even' with a fritware body costing £1.66 a kg. A Larger kiln should work out more efficient on energy I think so less extra cost.
 
I have two ball clays and a kaolin kicking around so after reading kaolin can take up to 30% frit I decided to start with the ball clays. Hyplas 71 and Hymod AT at £0.90 per kg (25kg bags). Not sure I am in the power or fiberglass industry but they sell it at pottery suppliers

 
Next are the frits that run from £6-10 a kg (25kg bags). I think they are pretty expensive in the UK.
I went with an Alkaline Frit (similar to 3110 but cheaper) and Ferro Frit 3124, 3134 and 3195 for the glaze and to try in the body.
 
At 5% frit to ball clay it will cost £1.16-1.31 per kg.
At 10% frit to ball clay it will cost £1.41-1.73 per kg.
At 20% frit to ball clay it will cost £1.93-2.56 per kg.
 
Looking at that I thought it was definitely worth trying as I could possibly get it under £1.66 a kg. I guess I need to factor in my time making the clay into the cost but if I am planning on casting I feel it would be similar anyway to making a stoneware slip.
I tested each ball clay with 5, 10, 13, 16 and 20% frit in the order Alkaline, 3124, 3134 and 3195. The last 4 tests have a 50/50 mix ball clay to kaolin and 20% of each frit. Fired to cone 03 and then boiled for 5 hours to get the absorption values.
The results actually came out better than I expected with Hymod ball clay and 10% alkaline frit getting to 0.5% absorption at £1.41 per kg I think B0011 I must have messed up as the data doesn't fit.
 
 
Colours are sort of accurate in this photo, not a very good camera on my phone.

 
Now I am experimenting with adding different Calcium Magnesium and Lithium fluxes to see what happens.
Reading that I could have issues with drying times using pure ball clay. It's interesting that the Hyplas has larger particles than Hymod but it is sold as the more plastic, maybe there's something I am missing.
Never did any working out for how much more the glaze costs so maybe that will make things look worse but hopefully it is such a small % total it doesn't make much difference.

Looks like the glaze is full of tiny bubbles and firing a little hotter has let them join together and start rising to the surface.  Firing again just let more of them join together so you can see them, I would guess the ones fired in the small kiln are still full of tiny bubbles but they are just hard to make out and look more like a texture.
A lot of gas can be chemically dissolved into the glaze as it melts. As you keep increasing the temperature the chemical solubility of the gas decreases along with more silica arriving into the melt also changing how soluble those gasses are. 
I feel whatever you try with different bisque temperatures the glaze will still look the same and produce thousands of tiny bubbles that can't join together and escape because of high viscosity and surface tension
 
 

Does it have a review button so you can make sure the program is correct and rule out that being wrong?

Can anybody can provide a reference for this, or more details to aid my searches?.
 I did stumble across https://digitalfire.com/picture/1068

Also a tantalizing comment in https://digitalfire.com/glossary/stoneware

PS I also found this of interest https://digitalfire.com/picture/c6Ho2e5Fsn

If you have a look at the underglaze it says "For best colour response at 1280 we recommend low or no Zinc stoneware glazes." Then have a look at the glaze you are using, it contains zinc. "Midfire to Stoneware Clear Glaze containing approx 5% of Zinc and 5% Calcium" Even though you fired to 1250C and not the full 1280C this combined with what may be a heavy application would be my hunch as to why you got the colour response you did.
Which porcelain glaze did you use? Have a look at what the writeup for it, see if contained zinc, you can also look at the Safety Data Sheet (SDS) for it if it isn't clear.
For your second question, for functional wares you want to fire the clay to it's maturity to make pots that are as vitrified and strong as possible. I don't know what the maturity for your clay is so I can't answer that one for sure.
I know it seems very wasteful to fire a kiln with just test tiles but this is what I would do rather than taking a chance on a kiln load of pots. Ask your supplier if they can recommend  a zinc free clear for your clay and underglaze and make some test tiles. Try the underglaze with 1,2 and 3 coats then glaze with a thin, medium and heavy application and see what happens. Sometimes the unexpected happens and we don't care for it because it wasn't what we were going for but I think the purple areas look nice on your pot.