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Base of cup keeps cracking?


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#1 Elmoclayman

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Posted 18 October 2012 - 02:29 PM

He guys, me again.

I have been making some castings using slip and have been noticing that the inside of the cup is cracking during the drying. It only cracks around the base. Cracks aren't going all the way through, but enough to where they are visible. I was wondering if you may have a suggestion of what might be causing this? Would specific gravity of the slip contribute to this?

Thanks again,
Brian

#2 Mark C.

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Posted 18 October 2012 - 02:47 PM

Are you adding darvon 7 as a defoculant?Are they real thick?
Is this the soldate 60 or a commercial slip body and is your soldate body a dry body made for slip casting?
Some more info is needed.
Mark
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#3 Elmoclayman

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Posted 18 October 2012 - 03:20 PM

Are you adding darvon 7 as a defoculant?Are they real thick?
Is this the soldate 60 or a commercial slip body and is your soldate body a dry body made for slip casting?
Some more info is needed.
Mark


Mark:
I am using Darvon 7 as a defoculant. The mugs when finished are about 3/8" think.

Soldate 60 is a Cone 10 commercial clay body that I use in my High School Ceramics class. I have a large amount of scrap left over, so I dry it out, wet is into a slurry and make the slip from that.

#4 justanassembler

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Posted 18 October 2012 - 04:39 PM

are you adding darvan 7 to your reclaim? It may be that the reclaim needs to be defloculated further (ie: too much water)... Im not sure if theyd tell you or not, but a lot of commercial bodies use darvan 811 which shouldnt require much if any additional defloculant in reclaim as the 811 is a lighter polymer


Are you adding darvon 7 as a defoculant?Are they real thick?
Is this the soldate 60 or a commercial slip body and is your soldate body a dry body made for slip casting?
Some more info is needed.
Mark


Mark:
I am using Darvon 7 as a defoculant. The mugs when finished are about 3/8" think.

Soldate 60 is a Cone 10 commercial clay body that I use in my High School Ceramics class. I have a large amount of scrap left over, so I dry it out, wet is into a slurry and make the slip from that.



#5 Mark C.

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Posted 18 October 2012 - 08:54 PM

Soldate has been around for 40 years and I'm very familiar with it-great thowing body-you may need a few additives to make it slip well. Call Jon Pacini at Laguna Clay Company and ask him what's needed.He can answer this in a heartbeat.
Mark
Mark Cortright
www.liscomhillpottery.com

#6 Elmoclayman

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Posted 19 October 2012 - 10:07 AM

Great! Thanks Mark. I'll give him a call today.




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