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Calculating Different Shrinkage Rates

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The same clay body can be quite different depending on where its cut from the pug.

 

I think this PowerPoint presentation Lecture #6 from Alfred University, "Particles: Orientation and Density", will explain it.

 

http://claystore.alfred.edu/rawmats/presentations/Raw%20Mats/Class-6%20%28particle%20orientation%29.pdf

Thanks Norm, that was really helpful. Page 34 has solved one of the puzzles we encounter at the day centre.

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Average shrinkage of 12% +/- 2% is the total shrinkage. For many clays, most of this shrinkage will occur as the clay dries. There will be very little if any shrinkage during bisque.

 

 

Norm- let me add my thanks for all of the detailed information.

 

Just a quick question as a follow-up on the point above.

 

I often need to fit a piece of Raku ware to a cone-six component (for example, Raku planter, cone-six base saucer).

 

Given the assumption that there is little or no shrinkage at bisque, is it pretty safe to assume that there's also minimal additional shrinkage during a raku firing? I wouldn't think that there'd be much added vitrification at that stage... but someone please correct me if I'm wrong...

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Average shrinkage of 12% +/- 2% is the total shrinkage. For many clays, most of this shrinkage will occur as the clay dries. There will be very little if any shrinkage during bisque.

 

 

Norm- let me add my thanks for all of the detailed information.

 

Just a quick question as a follow-up on the point above.

 

I often need to fit a piece of Raku ware to a cone-six component (for example, Raku planter, cone-six base saucer).

 

Given the assumption that there is little or no shrinkage at bisque, is it pretty safe to assume that there's also minimal additional shrinkage during a raku firing? I wouldn't think that there'd be much added vitrification at that stage... but someone please correct me if I'm wrong...

 

My porcelain shrinks between 3 and 6 % at bisque-If you are asking if you then raku it will kit shrink more?

The answer is yes if it gets over bisque temperature and no if its less than that.

M

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Average shrinkage of 12% +/- 2% is the total shrinkage. For many clays, most of this shrinkage will occur as the clay dries. There will be very little if any shrinkage during bisque.

 

 

Norm- let me add my thanks for all of the detailed information.

 

Just a quick question as a follow-up on the point above.

 

I often need to fit a piece of Raku ware to a cone-six component (for example, Raku planter, cone-six base saucer).

 

Given the assumption that there is little or no shrinkage at bisque, is it pretty safe to assume that there's also minimal additional shrinkage during a raku firing? I wouldn't think that there'd be much added vitrification at that stage... but someone please correct me if I'm wrong...

 

My porcelain shrinks between 3 and 6 % at bisque-If you are asking if you then raku it will kit shrink more?

The answer is yes if it gets over bisque temperature and no if its less than that.

M

 

 

I bisque to 1900, fire to about 1850... so I guess no additional shrinkage?

 

Obviously, the important thing is for me to collect some hard data on my own clay body...

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