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High Bridge Pottery

Member Since 19 Feb 2013
Offline Last Active Today, 10:19 AM

#122447 Adding A Touch Of Gerstley Borate?

Posted by High Bridge Pottery on 17 February 2017 - 04:37 PM

Adding 10% GB may just make your glazes glossier and a bit more fluid. Here is a test tile I did using only GB as the flux. Going up increases in Kaolin and to the right increases in Silica. There's a certain point that you get some depth with 'boron clouding'. I remember it being related to how much silica is in the recipe too. Cone10.


Do you have any rutile/titanium/tin? Have you tried layering glazes?



#122307 Home Made Kiln Controller

Posted by High Bridge Pottery on 14 February 2017 - 05:02 PM

It has been a while since I got to dabble with electronics. Looking into automating a gas kiln. Found a ball valve + actuator that needs 0-10v signal sent for how open it is. After some googling I found this op-amp circuit for doing that exact job so set about making it.




Took me a few failed attemps (wired the 24v positive up from actuator up to my raspberry pi and killed it, same with chip) but once I made sure it was the right circuit it all works perfectly.

Realised I never posted the MAX31855 circuit so here is that one too.




Tested it out on the kiln today and it works a treat. Still lots more work for actually programming the thing to do sensible things.





#122237 Clay In Glazes.

Posted by High Bridge Pottery on 13 February 2017 - 01:46 PM

If you make glazes thixotropic with vinegar they can 'go solid' before any drips form. Also found this can make glaze crack off the pot if you add too much. 

#121571 Firing Earthenware Jugs - Basic Questions

Posted by High Bridge Pottery on 02 February 2017 - 08:34 AM

If you have some kiln element you can make your own stilts. Cut off little 'stilts' from the elements, stick them into a clay base and bisque. Job done. 


Have you tried firing some earthenware to cone6 yet to see if they hold up/vitrify at cone6?

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#119681 Ian Currie Test Tiles Forums?

Posted by High Bridge Pottery on 02 January 2017 - 04:36 PM

For 6 months my brain has been empty but somebody just poured glaze into my ears :blink:.



#119324 Raw Glazing At Cone 6-8?

Posted by High Bridge Pottery on 28 December 2016 - 04:07 PM

I was having a look at John Brit High Fire book today and it has a little section in there about single fire if you have the book. It did say that high clay content is needed for leather hard glazing but most glazes could work on bone dry pots as they have done the shrinking.

Never tried it myself.

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#119323 Silica In Glaze And Body To Ensure Good Fit?

Posted by High Bridge Pottery on 28 December 2016 - 03:59 PM

Where can I find the jello coated cookies?

#118503 Qotw: What Are The Top Five Things In Your Studio That You Would Not Part Wit...

Posted by High Bridge Pottery on 15 December 2016 - 05:26 PM

I had to move out my studio not so long ago. Looking around my bedroom I can see many more than 5 items that I couldn't part with and a studio of 0 size  :ph34r:

#118116 Community Challenge #8

Posted by High Bridge Pottery on 08 December 2016 - 04:40 PM

Soooo.. Again not doing so well with the ideas. Looks like my brain is AWOL in that area. 


I have removed my half baked rambling poetry and added a challenge submitted to the ideas thread.


Note to self, do more thinking.

#118110 Small Kiln In House (Not Garage Or Basement)

Posted by High Bridge Pottery on 08 December 2016 - 02:26 PM

240v does make having a reasonable sized test kiln on household wiring much easier.

#117697 Magic Ingredient / Simple Ingredient Change To Turn Cone 10 Glazes To Cone 6?

Posted by High Bridge Pottery on 02 December 2016 - 03:40 PM

I tried using colemanite once and it jumped off the pots.


Attached File  12277103_10156410647675045_40461125_n.jpg   51.49KB   0 downloads


Calcium borate frit is about the same price as GB and I prefer that.

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#117613 Technical Requirements Skutt Kiln

Posted by High Bridge Pottery on 01 December 2016 - 01:00 PM

The 50amps is just the rating of the kiln sitter, think of it as 'up to 50amps' and if you go over that 50 it will probably break.


I think the general idea for safety is a breaker 25% larger than the kiln but I have run 30amp kilns on a 30amp breaker.

#117418 Am I Screwed?

Posted by High Bridge Pottery on 28 November 2016 - 05:12 PM

They might look better than usual, you never know. At least you found it before it was a 20 hour hold. It could have even worked out at your cone 5 down 6 half way assuming the first time it did hold and you have only added 27min.

#117243 Kiln Conversion Updraft Downdraft Chimney?

Posted by High Bridge Pottery on 26 November 2016 - 05:06 PM

I ended up making a longer video with more footage.


#116836 Is Cone 6 Practical For Domestic Ware In The Uk?

Posted by High Bridge Pottery on 21 November 2016 - 12:36 PM

It is interesting, the clay sold as terracotta has a firing range up to 1220 but all stoneware goes up to 1260/1300.


I think you are probably right that clays sold as stoneware are cone10 clays even if their range goes from 1080-1280. That doesn't mean there is not one out there that would suit cone6 but I have never found much useful data about the clays out there.


I would try a terracotta rated to 1220 and see if you have any luck.


There is one here rated to 1120c but also says 'will vitrify at high stoneware temperatures' after having a look through valentines clay it looks like a few possible cone6 bodys could be filed under white earthenware/terracotta.


"KGM Body     can be fired 1080-1120oC

White to Off White at higher temperatures.

Smooth. Cost effective white earthenware clay which will vitrify at high stoneware temperatures. Due to very fine grog will give a light speckle at the highest te


"Potclays 1141 Studio White Earthenware (LT25)


Smooth. Ivory white very plastic white clay for throwing.1100-1220oC"


Potclays actually give this clay a vitrification range of 1180-1250 but the firing range above. Who decides to put these things.


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