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Controlling Shrinkage in Casting Slip


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#1 timbo_heff

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Posted 22 April 2013 - 01:09 PM

Any advice on how to control the expansion in this low fire white casting slip?
It is shivering off commercial glazes:

.400 TEXAS TALC
.250 C&C
.200 HYDRITE FLAT
.100 MINSPAR 200
.050 VICRON 25-11
Any ideas much appreciated !




#2 Mark C.

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Posted 23 April 2013 - 01:39 AM

.400 TEXAS TALC
.250 C&C
.200 HYDRITE FLAT
.100 MINSPAR 200
.050 VICRON 25-11
Any ideas much appreciated !

Well for starters please give some more details on the materials like the C&C? what is that?
.400 Talc
.200 C&C what is this material?
.200 Hydrite flat this is EPK but an unusual brand used in paints I think
.100 Minspar-just a spar
.050 Vicron which is whiting or limestone take your pick
You said(It is shivering off commercial glazes)
do you mean low fire glazes are shivering off the clay or are you applying this over the glaze and it comes off?
Mark
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www.liscomhillpottery.com

#3 timbo_heff

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Posted 23 April 2013 - 07:59 AM

.400 TEXAS TALC
.250 C&C
.200 HYDRITE FLAT
.100 MINSPAR 200
.050 VICRON 25-11
Any ideas much appreciated !

Well for starters please give some more details on the materials like the C&C? what is that?
.400 Talc
.200 C&C what is this material?
.200 Hydrite flat this is EPK but an unusual brand used in paints I think
.100 Minspar-just a spar
.050 Vicron which is whiting or limestone take your pick
You said(It is shivering off commercial glazes)
do you mean low fire glazes are shivering off the clay or are you applying this over the glaze and it comes off?
Mark


Thanks For taking a look at this Mark !
The commercial glazes are shivering off the cast pieces.
From Digital Fire: C+C = White burning plastic ball clay: Considered by some as a stoneware clay, it fires very white and is used in white firing porcelains and stoneware for its excellent plasticity.The company describes it as a fine-grained engineered blend, well known for its excellent plasticity and fired properties. This consistent blend is suitable for a wide variety of forming processes, where a high degree of plasticity is required, such as dry pressing, jiggering, ram pressing and casting.

Hydrite Imery's A coarse particle, acid flocculated kaolin clay with controlled particle distribution.


#4 Mark C.

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Posted 23 April 2013 - 10:06 AM

Do you have a shrinkage % or test shrink% for this body?
Mark
Mark Cortright
www.liscomhillpottery.com

#5 timbo_heff

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Posted 23 April 2013 - 10:40 AM

Do you have a shrinkage % or test shrink% for this body?
Mark


Only test result I have:
500 degrees Celsius: – 9.93

#6 neilestrick

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Posted 23 April 2013 - 11:37 AM

I'd start with a real shrinkage test. Then we can go from there. 500C isn't even 1000F. You've gotta be fiirng hotter than that.

C&C is my favorite ball clay. It's wonderful stuff- more plastic and way more consistent than OM4. It's a blend of Champion and Challenger clays, from H.C. Spinks.
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#7 timbo_heff

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Posted 23 April 2013 - 11:45 AM

I'd start with a real shrinkage test. Then we can go from there. 500C isn't even 1000F. You've gotta be fiirng hotter than that.

C&C is my favorite ball clay. It's wonderful stuff- more plastic and way more consistent than OM4. It's a blend of Champion and Challenger clays, from H.C. Spinks.



That test was done by Gare; not sure why sooo low temp: but maybe some relative info will be informative:
From the same test: Standard slip – 9.11 and Miller NS1 slip – 7.8.


I am seeing online that a lot of folks use 50% talc in low fare casting slip: maybe that is the ticket?

#8 Biglou13

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Posted 23 April 2013 - 05:49 PM

Can you post pictures of "shivering". Please
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#9 bigDave

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Posted 24 April 2013 - 10:23 AM

Can you post pictures of "shivering". Please


off topic but I cant help but ask,

Why one would want to mix casting slip when it can be bought so cheaply and easily.

I have uses tons of laguna clay co. slip comes dry, 50 pound sacks, at about 25 cents a pound. So easy, its all in there

10 years using and always exactly the same, perfect glaze fit, etc

just cant imagine messing with ingredients and blending etc...

okay carry on,

good luck
big D

#10 timbo_heff

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Posted 24 April 2013 - 11:35 AM


Can you post pictures of "shivering". Please


off topic but I cant help but ask,

Why one would want to mix casting slip when it can be bought so cheaply and easily.

I have uses tons of laguna clay co. slip comes dry, 50 pound sacks, at about 25 cents a pound. So easy, its all in there

10 years using and always exactly the same, perfect glaze fit, etc

just cant imagine messing with ingredients and blending etc...

okay carry on,

good luck
big D

Hey BigD. I work at a place like laguna and we are vexed because this formula works for some and not others
I agree.. I would never make the stuff myself... nor will I ever make my own clay ! :)

#11 OffCenter

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Posted 24 April 2013 - 11:48 AM

Why one would want to mix casting slip when it can be bought so cheaply and easily.


To get a slip that works better and looks better than any you can buy.

Jim
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"But it does move," said Galileo under his breath.

#12 bigDave

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Posted 25 April 2013 - 04:28 PM



To get a slip that works better and looks better than any you can buy.

Jim

I suppose,
we did go through tons of supplies in school trying out recipes for casting slip, never came close to anything as good as the off the shelf stuff I use now

so that skews my view I guess.

carry on...




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