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timbo_heff

Member Since 24 Apr 2012
Offline Last Active Aug 29 2014 02:27 PM
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Posts I've Made

In Topic: Massive Crack In Single Firing

29 August 2014 - 12:05 PM

You are firing to 2450 ??

With a 3 hour hold??

 

That's probably cone 14 or 15 !

 

Not that that would be the cause of your dunting but probably not a good idea


In Topic: Free Glaze

26 August 2014 - 02:29 PM

The new Amaco Celadons for c6 are cool too:

They are blendable and have a clear and dark to add to modify the opacity for tons of different looks.


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 !