High Bridge Pottery
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Posts posted by High Bridge Pottery
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After looking at the manual posted in the other thread this controller seems a bit weird. T1 is the time taken to get to the NEXT temperature not the C1 temperature. That seems backwards to any controller I have programmed.
C1 0020c, T1 0030m
C2 0100c, T2 0030m
C3 0100c, T3 0600m
C4 1140c T4 0100m
C5 1240c T5 0000m
C6 0020c
That should go from room temp to 100c in 30min and hold at 100c for 30min. Then it takes 10 hours to get to 1140c (you could speed that part up) and then up to 1240c in 100m (60c/h)
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Is it frustrating because it is causing problems or just because you would like the cones to read the same numbers? If it's the second I wouldn't worry about it.
Neither of those schedules you have posted are aggressive. For me 100c per hour is slow, 200c fast and 250c is aggressive.
I bisque to cone 016/017 (that's a guess, I have never put a cone in a bisque kiln) in 4 hours doing 20 min to 100c, hold for 20 min, then ramp at 250c an hour up to 800c and hold for 20 min. You can see the kiln drop to under 250c an hour while it struggles from 500-600c as chemical water is lost but it catches back up to 250c and hour after that.
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At a guess, press the set key then use arrows to set the temperature of your first ramp. Press set again and use the arrows to set amount of minutes to take to get to that temperature. Repeat and end with a segment that has set temp and time of 0 (or if you keep pressing down after 0 there might be an end option). Maybe press set again or wait for it to go out of program setting mode then hold the down arrow until the program starts.
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I have never tried it myself, I wonder if changing the calcined kaolin for whatever clay body you are using would be a better colour match.
Kyanite seems to have some expansion at hotter temps so I wonder if that helps it join the crack together.
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Quote
Bob Chance on sat 17 may 97
My favorite bisque patch consists of equal parts calcined Kaolin and 100
mesh Kyanite mixed with equal parts liquid sodium silicate and white
(Elmer's) glue until the consistency of putty. Apply and sand when dry.
You can glaze over it.
Bob Chance -
Looks cool but even if they are giving it away for free I don't think it's worth it. Fiber walls look past their best and learning how all that system works will take a long time.
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I agree if you were only using frits then maybe it could be an issue to add whiting but at cone6 - cone10 I just don't see it. Even in the only related post underneath he is swapping talc for dolomite "While dolomite has a far higher LOI than talc it starts releasing the gasses of its decomposition much earlier and finishes well before talc." That's a cone6 recipe with 17% frit.
Even looking at his melt tests with frits at 1650 I can see 5 that are not exactly melted. https://digitalfire.com/project/comparing+the+melt+fluidity+of+16+frits
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Interesting that pricing is the opposite in the UK, whiting £1 a kg and wollastonite is £2.46 a kg. Probably based of what's in the ground locally.
Melting better is a good reason to use it.
I am yet to find any proof that whitings LOI causes issues with glazes, it starts at 700c (1300f) and over by 900c (1650f)
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Do you have a particular reason for using wollastonite? I found swapping wollastonite for whiting and silica made no difference to glazes and whiting is much nicer to work with.
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@PeterH No I didn't think you were being critical of my advice, I have just started using glazy and added all my materials but then started questioning myself if that was the right thing to do. I know most exist but it's nice to be in control of materials you use.
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Is it bad practice to create/duplicate all your materials on glazy?
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On 3/1/2024 at 3:59 PM, Hulk said:
Check to see if this Operating Manual matches your unit?
There's wiring diagrams at the end.
Note the thermocouple spec, page thirteen.
See also the current/power specs...Topworker P59750 P59760 P59770 P59590 manual A.pdf (wsimg.com)
Didn't realise Hulk had found the right diagram ages ago
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I don't think it's a good idea to use a 40amp breaker if they suggest 10. The 250v fuse or something is connected to the coil that switches the relay and you should leave it there.
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I have the diagram for a different kiln but it looks pretty similar, mine is just a bit smaller. The website seems to be compressing it so I will find another upload.
https://freeimage.host/i/JVcrpSa
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I would just email/ring pottery crafts for the circuit diagram so you knows what goes where.
A lot of uk kilns seem set up for a simple swap from single to three phase. You will need a much bigger breaker and wire going to the kiln for single phase but the internals should stay the same. Most of the three phase just use each leg as it's own 240v supply.
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Trying some frits as glazes, fired to 1100c (2012f)
- Hulk and Kelly in AK
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I finally got around to doing a few glaze tests and brushed some on these mugs. Can't feel any texture through the glaze so pretty happy with the results as I didn't do any cleanup on the mold print.
Need gum for brushing, seem to have lost mine.
Need to go back and work on my clay, maybe.
The clay is great except it still takes 1.5-2 hours to cast the larger mug and it likes to hang onto bubbles.
Fires like a dream, bisque in 4 hours (20 min to 100c, hold for 20 min then 3h to 800c and hold for 20 min) and glaze in 5.5. I could go faster on the glaze but after 800 my kiln stops climbing at 250 c/h. At 1000 to 1100 it can only manage 80 c/h but that's ok for hitting 1100 cone03.
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The digital fire link seems a pretty good example of the difference a smaller mesh can make.
The smaller the better in my opinion for melting silica. I remember back to my bubble experiments and removing quartz/silica additions and trying to source from feldspars/clays always had a better melt. Glazenerd did send me some super fine silica that is still on my list to test about 7 years later
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They seem to agree with my theory that it's about crystalline silica and being high expansion in crystal form and low expansion when fused/melted/dissolved.
As a wise member once said "it depends"
Maybe your glaze is full of unmelted silica because you got 200 instead of 325 mesh and firing hotter lowers the expansion of your glaze, maybe your glaze is all amorphous and going hotter lowers the expansion of the clay crazing the glaze or a mixture of lots of chemistry melty and crystaly combined happens and it all evens out in the end and firing hotter makes no difference.
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I would theorise that firing hotter probably lowers the expansion of the clay, possibly by dissolving more crystalline silica and could make a glaze more likely to craze.
I'm not sure it's a good idea to relate the permanent shrinkage firing clay with coefficient of thermal expansion.
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I didn't think being damp would change anything that much but good to know it does
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Does the power go straight from the plug to these wires or is it coming from that silver box? Can you post a photo of inside the box? The wires zip-tied up look more suspicious than power going through the bricks to earth.
I am pretty sure all UK homes go through an RCD and there's quite a few of these old Cromartie kilns about but I have never heard of brick conductivity being an issue.
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If you know the specific gravity you can work out how much dry glaze you have in the quart or gallon.
First you divide the SG of the dry material by itself minus 1. A good estimate is 2.6 so 2.6/1.6 = 1.625
Now you multiply that by the SG of your glaze minus 1. Say your glaze is 1.6 then we would do 1.625 * 0.6 = 0.975
Finally we take 0.975 and divide it by your glazes SG. 0.975 / 1.6 = 0.609375 or 60.9375% dry matter. Then all you need to do is weigh a quart of glaze and multiply it by 0.609375 and you have the total dry weight of the glaze slip and can work out what x% will be in grams.
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Bisque firing frustrations
in Studio Operations and Making Work
Posted
It's my zero3 fritware clay, kiln is just a 40 litre rust bucket.
I would go with the cone program as it may dynamically alter the firing depending on how it keeps up with the rate of climb. Do skutt controllers do that?