[Clayart] Bill Carty and pinholing

PETER HAMER p.hamer at btinternet.com
Mon Mar 10 11:04:17 EDT 2014


Re-postingof the 10th message in 

https://groups.yahoo.com/neo/groups/clayart/conversations/topics/252441

John, Beth,
Dr. William Carty at Alfred claims firing
dehydroxylates kaolin (drives the water off it).  As a
result, he says, the fired surface of the clay is
somewhat hydrophobic (repels water).  Dipping the ware
in water, sponging it, etc permits the clay to attach
itself to some water (rehydroxylates the clay) and
renders the surface hydrophyllic again (attracts
water).  As a result, the surface is less prone to
glaze faults.
I do not know whether his statements are accurate.
I have never read this in the published literature.
I have not tested it personally.  There are other
variables, like glaze composition, surface roughness
of the ware, dust, etc. which would make a test
difficult.  I have found Carty to be a credible source
of such information, given that his Ph.D. is in
surface chemistry and he has worked quite a bit with
clay products, but I'm biased because he was my MS
advisor.
Good glazing,
Dave Finkelnburg

Regards, Peter

Presumably adding a surfactant (e.g. 1 drop of dishwasher rinse aid) would assist this process;
either to the wash-water or the glaze bucket.



________________________________
 From: Vince Pitelka <vpitelka at dtccom.net>
To: 'Clayart posting' <clayart at lists.clayartworld.com> 
Sent: Monday, 10 March 2014, 13:46
Subject: Re: [Clayart] tony's metaphor tangent - cornwall stone vs custer, mega-pinholes
 

Taylor Hendrix wrote:
"Eddy, heard a very interesting lecture by a ceramics engineer from Alfred,
Bill Carty. An interesting take away was his finding for the underlying
cause of pinholes. Not outgassing, not dirty bisque. Interesting."

Yes . . . go on . . . 
- Vince

Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka at dtccom.net  
http://iweb.tntech.edu/wpitelka/  




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