High Bridge Pottery

Even at $100/pound, say you put 30 grams of glaze on a mug and 3 grams of that is tin it's only 66 cent a mug in tin.
I don't let it put me off using it, I like tin  

Even at $100/pound, say you put 30 grams of glaze on a mug and 3 grams of that is tin it's only 66 cent a mug in tin.
I don't let it put me off using it, I like tin  

Re-reading Digitalfire the second paragraph seems relevant..
Glaze Shivering
https://www.digitalfire.com/trouble/glaze+shivering
Shivering is the opposite of glaze crazing, the fired glaze is under compression and wants to flake off the body, especially at edges. However the route cause is a mismatch in the thermal expansions of body and glaze, thus the process of resolving it is similar as for crazing. It it much less common because glazes tend to have a higher thermal expansion than bodies and because they can tolerate being under compression much better than being under tension. Of course, if a glaze is under compression on the inside of a vessel, the body will be under tension and this can cause failure of the piece.
When the body-glaze interface is not well developed an overly compressed glaze will be able to release itself much more easily, especially on the edges of contours. This can be the case, not only with low fired ware, but where engobes or slips are being used under the glaze. If the engobe does not contain enough flux to firmly adhere it to the body and develop hardness, it will not be able to bond to the glaze well.
PS Time for some rim-shaped test-tiles?

It a tricky one to decide, will the initial cost to get an electric kiln up and running save you money in the long term with lost ware and time you could be doing something else. 
 
I have semi automated a gas kiln adding a controllable valve onto the pipe but that is not the easiest thing to do. It just meant instead of turning it up every 20 minutes the computer did that for you. There was no brains really, the first firing I did have to turn it up via the computer and record what was set and run a simple program to repeat that for me the next firings.

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)

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)

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? 

Wollastonite has a much lower LOI than whiting (1.6% vs 43.9%) and has a lower thermal expansion coefficient (9.0 vs 14.8) (data from DigitalFire).  Wollastonite also provides silica in addition to calcium.   My glazes are high silica/low expansion by design, and wollastonite gets me there.  And finally, Wollastonite cost me $0.59/pound the last time I bought it, whereas whiting cost me $1.17/pound.  I'm sure I could rework my recipes to substitute whiting, but there is a certain amount of inertia involved in doing that, as I'm generally happy with the way my glazes are behaving on my clay.

If you click on the create option in the menu then choose new material you can add it that way if you have the frit analysis.

If you click on the create option in the menu then choose new material you can add it that way if you have the frit analysis.

My fingers! Seriously, they are my favorite pottery tools. 
Betty 

Didn't realise Hulk had found the right diagram ages ago .
 
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.

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)

Trying some frits as glazes, fired to 1100c (2012f)

Trying some frits as glazes, fired to 1100c (2012f)

No reason you can't put the water into the old glaze bucket to start with. I agree with sieving once unless you have a specific reason for doing that.

No reason you can't put the water into the old glaze bucket to start with. I agree with sieving once unless you have a specific reason for doing that.

No reason you can't put the water into the old glaze bucket to start with. I agree with sieving once unless you have a specific reason for doing that.

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.

No reason you can't put the water into the old glaze bucket to start with. I agree with sieving once unless you have a specific reason for doing that.

One of the reasons you are having difficulty with mold release is due to your print lines.  They add a texture that will cause the plaster to grip your 3D printed surface.  So any roughness needs to be filled in, sanded out, or smoothed over.  It doesn't mean that you can't have the texture but at least coat it with varnish or something to help smooth it out and fill in micro undercuts.  All those little places you have plaster sticking inside of the print lines are forming tiny undercuts.  The main problem with 3D printing, IMO, is that there is a TON of cleanup.    I 3D print resins of my horse sculptures and no matter how clean my prints, how much I fuss over no print lines, temperature and other issues still cause so many nit picky things that I can literally spend hours cleaning up a single print afterwards before it's usable for mold making.  
By the way, you can also 3D print originals or mold masters in rubber!  This is super nice for pouring plaster molds and works a lot better than using the hard plastic.  But again, you need super perfect printing because you won't be able to clean up rough areas in rubber as easily as you can with plastic resin.  So as the technology is still evolving and not nearly good enough unless you really, really know what you are doing and that's a steep learning curve.  I've been 3D printing two years now and there's still a ton I'm trying to fine tune.  So mostly I still use the old fashioned methods of pouring rubber and building mold boxes.
Pardon me - I see belatedly that others also pointed this out so I'll just agree with them!    (edited to add this comment)

I usually fire my kilns at night so I don't really see what's happening with actual temps in the kiln, but today I started it up in the morning and was in the studio in the evening and got to see exactly what was happening during the cooling cycle. I do a slightly-slow cooling cycle to even out the results in my 3 kilns because they all cool at drastically different rates due to their sizes. I do a drop from the peak down to 2000F, then cool at 175F/hr down to 1500F. This gives me identical results from all 3 of my kilns. This firing I'm talking about here is in my 10 cubic foot L&L EQ2827-3, which has 3 zones, and was packed very tight in the middle. I was surprised at just how much slower the middle cools compared to the top and bottom. This photo shows how it's going part way through the initial drop from peak temp to 2000F:

As you can see, the middle and the top are nowhere close to each other. In a normal firing segment, a 73 degree difference would stop the firing with an error code. So why isn't it doing that here? It's because the cooling rate is set at 9999, or full speed. Any time you use 9999, whether it's climbing or dropping, the controller lets the kiln do its thing and doesn't care if the sections aren't even. Firing up or down at 9999 is the fastest, but you sacrifice evenness. As the temp continues to drop, we see this:

Here you can see that the top section (TC1) has started firing again. The set point for this segment was 2000F, at which point it should start cooling at 175F/hr, yet the top section passed that by about 20 degrees before the relay kicked on and the controller stopped the drop. Why did it let it get so far below the set point? Because it's averaging the 3 zones. Once the average of the 3 zones hits the set point it will start to fire each section again as needed to match the set point.
I get a lot of questions from customers about error codes and cooling cycles. The biggest problem is that the kiln can't always keep up with the programmed cooling rate. There are a number of firing schedules out there on the internet that people are trying that use a rate of 600F/hr or more for the fast drop portion of the cooling cycle, and many kilns simply cannot cool that fast, especially the middle section. When you have a specific rate programmed, the controller will send out an error code if the kiln can't keep up with that rate. So if you want a really fast drop you should use 9999F/hr, not a specific rate. For most people doing slow cooling with cone 6 work it won't matter if the sections are not totally even during the drop. If you do need more precision, like if you're firing crystalline work and it's important that you don't overshoot any target temps, then you'll want to put in a slower drop rate that the kiln can actually keep up with, and the controller will keep the sections even and not overshoot set points.

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