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timbo_heff

Member Since 24 Apr 2012
Offline Last Active Aug 20 2014 12:59 PM
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Posts I've Made

In Topic: Cone 6 Body Or Cone 6-10 Body: Much Difference?

12 August 2014 - 02:24 PM

I was surprised to see how quickly the mor drops off!

It really is a quite a narrow range where it's water tight AND strong


In Topic: Cone 6 Body Or Cone 6-10 Body: Much Difference?

11 August 2014 - 12:02 PM

 

How does one tell if its cone 6 is under fired , or cone 13 is over fired ?

 

Plot the Apparent Porosity curve and look for the minimum.  It'll be a U shaped curve.  That is the cone that the body is "mature at" and should be the firing cone.  The flatter the bottom of the curve, the more "forgiving" the body will be to firing variations within the kiln as well as for general under or over firing.

 

You also then align this information with a MOR test curve for strength.  You are trying to get the minimum porosity and the maximum MOR to basically overlap on the same cone. 

 

3 percent porosity is a LOT.  Asking for issues in functional tablewares, in work destined for outdoor installations, or things like pool tile, and sinks and such.  Shoot for something below 1%.  The closer to 0 the better in general.  0.5% is a nice optimal target..........hard to hit without dropping the MOR.

 

best,

 

....................john  

 

 

 

How does one tell if its cone 6 is under fired , or cone 13 is over fired ?

 

Plot the Apparent Porosity curve and look for the minimum.  It'll be a U shaped curve.  That is the cone that the body is "mature at" and should be the firing cone.  The flatter the bottom of the curve, the more "forgiving" the body will be to firing variations within the kiln as well as for general under or over firing.

 

You also then align this information with a MOR test curve for strength.  You are trying to get the minimum porosity and the maximum MOR to basically overlap on the same cone. 

 

3 percent porosity is a LOT.  Asking for issues in functional tablewares, in work destined for outdoor installations, or things like pool tile, and sinks and such.  Shoot for something below 1%.  The closer to 0 the better in general.  0.5% is a nice optimal target..........hard to hit without dropping the MOR.

 

best,

 

....................john  

 

Here Big Lou:

This graph shows how little range is where it is vitreous but still at max strength : and this is from a clay that is touted as having a much better range than most commercial clays:

(Matt and Dave clay: out of business though)

matt dave SCIENCE 25

 

 

 


In Topic: Reduction Kiln- Too Early?

11 August 2014 - 11:42 AM

IF it's 300 bucks for more than 300 bricks it's prob worthwhile:

... not even thinking for a gas kiln but to save the bricks for when you are ready to build your wood kiln!

 

Building even a small anagama takes a heck of a lot of of hard and soft bricks that are  roughly $3 each: so a chance to buy any bricks (presuming they are not already totally spalled or odd sized) for anything less than $1 each may be a worthwhile investment in your future !


In Topic: Personal Pottery Video

01 August 2014 - 01:59 PM

You can find music that has the "creative commons" license.

Much under that is usable with just a credit.


In Topic: Help - Feldspar Types?

15 July 2014 - 01:59 PM

G200EU : from Spain is now available: it is close to the original g200