High Bridge Pottery

There's a few ways you can make file size smaller without actually changing the size of an image. Different file types like .png .jpg .gif .webp all work in different ways and would give you different file sizes for the same image.
You can also change how many pixels per inch are in the image, the camera is probably around 300ppi but somewhere around 72ppi is suitable for the internet and it means there's a lot less data in the file. 
When exporting images in photo editing software you can also specify how much compression you want further reducing the file size.
 
It all gets a bit complicated but if you go to https://cloudconvert.com 
click 'select file' and choose the image you want to resize
change the 'convert to' dropdown so that you have webp selected (it doesn't have to be webp you can also stick with jpeg but the compression is a lot easier to see)
click the spanner icon and find where it says 'Quality' and input 60 into the box then click ok
Now click convert and download your image, if it is still too big reduce the number you enter into the quality box. You can go as low as 1 without being able to see much difference but your file size will be way way smaller.
 
Hope this helps.
 
 

Had a look through my microscope at the glazes. The low expansion has smaller and fewer bubbles.
I did read on digital fire about holding on the way up and on the way down to reduce micro bubbles so I may try that next time and see if it actually reduces the bubbles. My guess is it wont from past experience but always worth trying.
 
Interesting that the purpleish stain seems to reduce the bubbles even more (or maybe the stain hides them) and the blueish stain makes the surface look a bit devitrified and must be more refractory. Going to do some experiments colouring slip instead so I shouldn't have much variation in the finished glaze surface and need a different glaze recipe for different colours.
 
Low

 
Lowest

 

 

 

I am very happy with the results so far  especially after being educated in cone 6-10 and thinking that's the only way to get functional/vitreous ware for a long time.
 
Glaze needs some more testing to make sure it's durable and resistant enough but I can't see any problems with the low bisque. Having a quick look at the cone04 limits I seem at the higher end of Silica and Alumina and hopefully a good sign.
They are all a bit thinner than I would make functional ware so the extra thickness could cause issues burning things out. It seems mostly related to Lignite so maybe there just isn't much in this Dorset ball clay to cause problems.
 
It would be great to develop it into a throwing body too. Adding bentonite could mess with the porosity so more testing needed for that. 

Ran a few glaze tests with the low and lowest expansion glazes from a few posts above, I also tried dropping the clay by 10% and increasing frit and petalite but they settled out within 30 min and didn't leave a nice layer on the bisque so that wasn't a good idea.
Can't see much visual difference in the surface between the low and lowest expansion glazes, need to crack out the microscope and have a closer look but I feel the low expansion is better as I don't need the talc or zinc.
 
I was also interested in how quickly my kiln dropped in temperature from 1100c. The first 100c dropped in 12 min, the second 100c dropped in 15 min and the third 100c dropped in 20 min. Pretty quick but it's a small kiln with a not so great lid. 
 
Low: left has two dips of one second and right two dips of three seconds. Same for all the photos.

 
Lowest:

 
Also tried a few glaze/body stains at 3% and 7%, in the low expansion glaze. They advise sieving the glaze after adding colour but I neglected to do that to see how bad it would be. I have an orange stain too but ran out of space to attach more photos on this post and it was my least favourite.

I am very happy with the results so far  especially after being educated in cone 6-10 and thinking that's the only way to get functional/vitreous ware for a long time.
 
Glaze needs some more testing to make sure it's durable and resistant enough but I can't see any problems with the low bisque. Having a quick look at the cone04 limits I seem at the higher end of Silica and Alumina and hopefully a good sign.
They are all a bit thinner than I would make functional ware so the extra thickness could cause issues burning things out. It seems mostly related to Lignite so maybe there just isn't much in this Dorset ball clay to cause problems.
 
It would be great to develop it into a throwing body too. Adding bentonite could mess with the porosity so more testing needed for that. 

+1
 

Wow! Look at that. Glazed vitreous ware at cone 03. I’m not seeing any obvious glaze defects, looks like your “low” bisque temperature isn’t causing problems. Cool!!!

@glazenerd can you post a picture of what you're talking about here? With the ceramic TC blocks typically used in these kilns, I don't see how the exposed ends of the wire could possibly be touching each other since they're attached to the block a good 1.5" away from each other, and the rest of the wire has insulation on it. Were the wires stripped back really far?
@AMO only the very ends of the TC wires should be stripped back, just enough to fit into the holes in the block. Also, fold over the ends of the wires so they're double thick under the screws. I highly doubt your thermocouples are actually worn out, but clearly there's a problem in the system. Was the original TC you replaced clearly worn out, or did it still look okay? Since you were in there changing the elements, it's possible that there's a kink or break or loose connection in the thermocouple wires. The test you ran only checks that the controller is reading correctly, which is rarely the problem. Check to make sure there's not a break in the TC wire under one of the screws on the block. I see that happen a lot, and it will give you spotty readings or random fails. If everything looks good there, take the two ends of the TC wire out of the block and hold them together. It should read room temp, or the temp of your fingers. Then wiggle around the wires while they're together and see if the reading changes. If it does, then there's something wrong in the wires themselves.

This problem seems oddly familiar to me. I had 2 Paragon kilns that the ever fatal error codes; and I likewise replaced thermocouple and elements of one of the two. After replacing both an one: the beloved error code again. So I took the thermocouple wiring block apart again and restrung the thermocouple wires again- another TC fail. Took it apart again; this time while I was mounting the terminal block back on the kiln; I noticed the thermocouple wires compressed, and touched each other. I took it apart again, this time I put some insulating fiber between the thermocouple wires and gently held them apart while mounting the terminal block back on the kiln wall…. No more TC error after that.
Tom

I wasn't planning on testing a hotter bisque unless I get some issues further down the line. 
 
There''s no exact data on the melting point I can find online other than it has a firing range 860-1060C. (1580-1940f)
Not sure if that means 860 is the melting point as I assume they are specifying when it's a usable glaze. I will add some pure frit to the next bisque to see if they are melting or not. 
 
Are they doing a hard angle with the coils still intact or more like a front loader with what we call hairpins where the element is unwound in the middle? I had a job winding kiln elements for a while, mostly for skutt kilns and they had a similar diagonal across the brick. 

Finally got around to trying a bisque firing  thought I would try 800c (1472f) first and go hotter if needed but seems to have gone pretty well. They sound like bisque, have to wait and see how they go in glaze application. Haven't got any cones that low so not sure what cone I managed.

 
I always used to do 100c/h for a bisque but this time I was up around 230-250c/h with no problems, a little hold at 100c just incase. Total firing time is 4 hours. Seems like I didn't have to be so cautious previously.
 
Here's the graph of the firing.

Still intact, but a much harder angle that requires a couple pins to keep it from coming out of the channel at the bottom turn.

Thanks for the update! Are you going to do some more tests at different temps to see how hot you can go with the bisque? I feel like the hotter the better to ensure good burnout? What's the melting point of your frit? 
I love how they did the transition element groove on your kiln. It makes so much more sense than the hard angle the US kiln manufacturers like to do.

A belated posting on this topic.
Before and after of cyanotype on bisque - and re-bisqued.
My next test will be reprinting and re-firing, however many times needed to get the iron to build up into a less subtle image.
 

Been a while since I was able to squeeze one of these into a firing.
Here's the latest test.  Exposing the cyanotype twice is helping keep the image from fading so much.
Next step is spraying a clear glaze over it to see if that will keep the image from evaporating during Cone 10 firing.  Leda is just so so  and the swan is fading, so I also think a less contrasty negative and a third exposure to build up the iron.  We'll see.

Before you adjust any large batch of glaze, it’s a good idea to take a sample out and work out the problem on that. I agree with Bill that often glazes do just need a bit more water, especially if you’re working at cone 10. 
Sometimes though, thinning the glaze in the bucket makes the fired result less desirable. It’s not necessarily wrong, but maybe you don’t like the look of it. In that case you want to adjust how it flows, or the viscosity, with a deflocculant to make it more fluid (darvan) or a flocculant to make it thicker (epsom salts). 
As to why you’d want to adjust the viscosity of a glaze with water vs flow adjusters, Sue McLeod posted this the other day, and it’s a concise description with lots of images describing just that. (It should open in your browser, even if you don’t have the instagram app.) https://www.instagram.com/p/Cn2dMQHOTNP/?igshid=YmMyMTA2M2Y=

I would say in the UK 1300c and cone 10 and are pretty much interchangeable even if most kilns wont manage 150c/h for the last 40 min of the firing up to 1300c.
 
 
I would test what voltage you have in the studio over a few days and get the elements made for that voltage. The UK is supposedly 230v but I get 245V at my house so any elements designed on 230v will draw more power on 245v. Would be worse the other way around running 240v elements on 230v as then you will be down on power.
Just realised it is a front loader which tend to be more complicated than top loaders. Just a guess at the elements inside being 4 in the side walls and two in the floor. The side wall elements may all be the same spec but the floor will possibly be different.
Need to know the length of the tails (probably double what they are now so you have extra to play with/cut off, maybe 9-12") what length each bit of element is in the wall and how long each hairpin is. Also need to know what gauge the wire is, the internal diameter of the coil (maybe 1/2 or 3/4") and how they elements are wired up. Once you know how they are wired up we could possibly figure out what resistance they should be.
A bad drawing to maybe help.

I would say in the UK 1300c and cone 10 and are pretty much interchangeable even if most kilns wont manage 150c/h for the last 40 min of the firing up to 1300c.
 
 
I would test what voltage you have in the studio over a few days and get the elements made for that voltage. The UK is supposedly 230v but I get 245V at my house so any elements designed on 230v will draw more power on 245v. Would be worse the other way around running 240v elements on 230v as then you will be down on power.
Just realised it is a front loader which tend to be more complicated than top loaders. Just a guess at the elements inside being 4 in the side walls and two in the floor. The side wall elements may all be the same spec but the floor will possibly be different.
Need to know the length of the tails (probably double what they are now so you have extra to play with/cut off, maybe 9-12") what length each bit of element is in the wall and how long each hairpin is. Also need to know what gauge the wire is, the internal diameter of the coil (maybe 1/2 or 3/4") and how they elements are wired up. Once you know how they are wired up we could possibly figure out what resistance they should be.
A bad drawing to maybe help.

When you reduce an iron bearing clay body, the iron goes from red to black, and then the surface reoxidizes during cooling. If you cool in reduction, then the iron stays black. You need a clay body with 4-4.5% iron if you want black. To do it well, you need to be able to seal off the kiln but still be able to introduce a small amount of reduction. In a wood burning kiln, that means sealing up all the air holes with clay, and tossing in just a couple small scraps of wood every 10-20 minutes as it cools, down to a temp where it won't reoxidize. Very slow and boring process. In a gas kiln you seal off the burner ports but leave a small pilot flame burning for the reduction. Introducing small amounts of air can result in bright flashes of color on the surface. The first photo below is a teapot by John Neely, who pioneered reduction cooling in the US at Utah State University. It's not black clay, it's reduction cooled brown clay. The second is a piece by Susan Harris of Southern Utah University. Susan is a master of getting bright flashing in her reduction cooling pieces.
  

Are these 20 gram tests? 
Ferro 3249 is just under $500 / 50 lb bag here. (I've changed my glazes to remove it, too expensive now and I can make do without it)
Comparing the 3 frits, if you need a low COE one I'ld go with the 2279. If you are aiming for Hansens recipe increase the amount of 2279 to match the magnesium then tweak the silica etc. Might not need it at all. Would be interesting to see the melt difference between fritted magnesium vs supplying it from talc or dolomite, thinking it could be significant at low range.  COE figure on the 2270 probably doesn't represent real world tests given that zirconium will in theory increase COE but as it doesn't melt it acts as little road blocks in the glaze and decreases the chance of craze lines propagating. 

Not sure, relying on memory re reduction,  but some folk used to start reduction not far above 900dC and stop reducing quite low. Got lovely peachy and soft wines. Here, try to get stuff from John Eagle, he wrote about his practice, could be completely bad memory though. I had to fight not to get reduction.

Hey Min,
Interesting conversation. I only cast earthenware in the 80's when I just started out. Minnesota Clay mix. Having craze issues I soon moved to stoneware, Duncan. (rumored to have been "Bmix") and then to my own mix of cone 6 porcelain. (Dorothy Hafner)
Coincidentally my studio neighbor just bought a 100lbs of something called, "Zero4". I was just reading up on it before I saw this posting. 
Good Luck High Bridge. Great to see you taking this on.
 

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.