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High Bridge Pottery

Member Since 19 Feb 2013
Offline Last Active Today, 05:47 PM

Topics I've Started

Specific Gravity To Calculate Dry Weight.

Today, 12:27 PM

Can somebody please check my maths :D Seem to think about this for a long time and keep getting confused.


If I have a specific gravity of 1.5 and I weigh out 250 grams of glaze, that means I have 100g water and 150g glaze?


Or another way, I get 111ml of glaze that would weigh 166.7g or 66.7g water and 100g dry glaze?


Glaze Test City

08 October 2015 - 10:34 AM


Strange Orange Spots, What Is It?

01 October 2015 - 01:56 PM

Bought some white stoneware a while back, never really used it too much. Made some test tiles thinking it is probably some weird mould and would fire out. That didn't happen. What is the stuff? 


Wet clay, you can see the layer.



Bisque that is really bad



Still there when fired, not so much on these one as the bisque yet to be fired.


Kiln Conversion Updraft Downdraft Chimney?

30 September 2015 - 02:37 PM

I am getting a burner :D happy days. I was informed that it goes from candle to burning paint off the wall at 10 metre. Said I would be getting I think 45,000 BTU at 3 psi. Venturi. Comes with everything needed except the gas tank. Kiln is 5.05ftI got 60,000 BTU for the kiln but supplier said he thought less was fine.


I really want a downdraft kiln, but is it worth it? I have a bias towards them from research.


Seen Simon Leach kiln with the chimney inside but could I work one outside? The chimney would go out the base/side (not sure yet) and I would have a better divider in the middle that is not taking up so much space.






Ignore the very wobbly chimney stack  :lol:



Matte To Gloss Glaze Chemisty With Al2O3

16 September 2015 - 09:01 AM

So I thought I slightly understood glaze chemistry. Been having a look at a few of my tests in more depth.


Here is a 'glaze' that is going from this very stoney matte to glossy with only really adding Kaolin  :unsure:

The bottom is the left table, middle middle and up right.


Thinks Kaolin = refractory stuff, so it wouldn't make something go glossy.  All that really seems to be changing in the chemistry is the increasing Alumina, in non unity the silica hardly moves so I think that jump in unity value is because of the increase in alumina too.







All the flux going down, Al2O3 going up, SiO2 staying about the same. Less flux, more alumina = gloss. Very confusing.