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High Bridge Pottery

Member Since 19 Feb 2013
Offline Last Active Yesterday, 04:22 PM

#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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#116695 Handles Not Blended

Posted by High Bridge Pottery on 19 November 2016 - 01:09 PM

I am in the no blending club. Saves me 3-5min trying to make it look even and smooth. Never did like the marks sponges leave.

#116618 Stoneware Glaze Unexpectedly Crazing :(

Posted by High Bridge Pottery on 18 November 2016 - 11:09 AM

It does probably have quite high expansion with all the soda feldspar. Lithium will help the crazing. If you have no lithium carbonate you could swap out say 5 of the soda feldspar for a lithium feldspar (if you have that) and see if it fixes the crazing.


Is it leaking out through the bottom? Could be that the clay is underfired even at cone8. Usual rubbish from the company that "Scarva Earthstone Original White matures between 1180°C-1280°C" 

#116534 Clear Glaze Changing The Color Of Glaze/clay Body Below?

Posted by High Bridge Pottery on 17 November 2016 - 07:42 AM

I have seen clear glazes in oxidation tend towards blue in reduction firings on porcelain. Not sure what the cause of it is but reduction brings out the blues.


Here is a quote from digital fire in the blue section, any iron will seem to send the glazes blue in reduction. I think that is giving the blue hue throughout the glaze with cobalt sending the glaze brighter blue.



Oxides - Fe2O3  

In reduction glazes Fe2O3 tends to fire bluish or turquoise to apple green with high soda (boric oxide may enhance). 0.5% iron with K2O may give delicate blue to blue green.


They also say "Iron glazes will move toward blue if alumina is low."


Bit more reading and I found this on another website.

"The cup (fig 4) with iron glazes was fired under reducing conditions. The glaze on the inside contains 0.5% iron(III) oxide and the glaze on the outside 10%; the reducing power of the CO was enough to convert the iron in the inner glaze into Fe(II), but the concentration of iron in the outer glaze was just too high."


#116364 Glaze Ingredients Req'd To Bring Out Effect Of Iron In A Clay Body?

Posted by High Bridge Pottery on 15 November 2016 - 11:30 AM

I agree about the oatmeal spodumene kinda glaze. Seen a very similar effect with a glaze called Oatmeal white. Will see if I can track down the recipe from the friend who used it.

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