Orchard Valley Ceramic Arts Guild on sun 10 feb 02
I recently started working in a new studio, using
a new clay body and new glazes (new to me, in any case).
I use slip trailing for surface decoration on my work.
I've been using this technique for years, with no problems.
At the new studio, I successfully bisque fired some of my work -
no problems there. But when the work came out of the glaze
firing, the slip-trailed decoration had popped off in several
places. I subjected the remaining pots to some moderate
heat-cold cycling, and more of the slip popped off.
Since there was no problem after the bisque firing (the
slip is made from the same clay body as the pots), am I
correct in thinking that this is a glaze fit problem? In other
words, stress between glaze and clay expansion causing the
slip trailed decoration to fracture?
Or am I missing something more basic?
Thanks,
Bob
- - - - - - - - - - - - - - - - - - - - -
Bob Nicholson
Webmaster, Orchard Valley Ceramic Arts Guild
http://www.ovcag.org/
ADAM JARZEMBOWSKI on mon 11 feb 02
>From: Orchard Valley Ceramic Arts Guild
>Reply-To: Ceramic Arts Discussion List
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: slip trailing popping off
>Date: Sun, 10 Feb 2002 08:45:02 -0800
>
>I recently started working in a new studio, using
>a new clay body and new glazes (new to me, in any case).
>
>I use slip trailing for surface decoration on my work.
>I've been using this technique for years, with no problems.
>At the new studio, I successfully bisque fired some of my work -
>no problems there. But when the work came out of the glaze
>firing, the slip-trailed decoration had popped off in several
>places. I subjected the remaining pots to some moderate
>heat-cold cycling, and more of the slip popped off.
>
>Since there was no problem after the bisque firing (the
>slip is made from the same clay body as the pots), am I
>correct in thinking that this is a glaze fit problem? In other
>words, stress between glaze and clay expansion causing the
>slip trailed decoration to fracture?
>
>Or am I missing something more basic?
>
>Thanks,
>
>Bob
>- - - - - - - - - - - - - - - - - - - - -
>Bob Nicholson
>Webmaster, Orchard Valley Ceramic Arts Guild
>http://www.ovcag.org/
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
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To eliminate the glaze expansion factor I would go ahead and do some slip
trailing on your pot then fire the piece to your glaze temp (without glaze)
and see if your slip is still poping off.
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Ron Roy on wed 13 feb 02
Hi Bob,
I don't think it's a fit froblem - if the slip and the body are the same.
I suspect the slip - as it dries - shrinks enough to loosen - try picking
some of it off of the bisqued ware.
I recommend defloccing - I use Darvan 7 - the slip to cut down on
shrinkage. I also apply some vinegar to the pot before squirting slip on -
acts as a wetting agent and gives a better bond.
Best to apply slip on ware that is wetter rather then dryer - like right
after trimming. When I do my platters I put the slip on before trimming -
let it set for a day and then trim. I found that adding slip to half dry
trimmed porcelain can be a bad experience.
I wonder if the drying in your new studio is part of the problem?
RR
>I recently started working in a new studio, using
>a new clay body and new glazes (new to me, in any case).
>
>I use slip trailing for surface decoration on my work.
>I've been using this technique for years, with no problems.
>At the new studio, I successfully bisque fired some of my work -
>no problems there. But when the work came out of the glaze
>firing, the slip-trailed decoration had popped off in several
>places. I subjected the remaining pots to some moderate
>heat-cold cycling, and more of the slip popped off.
>
>Since there was no problem after the bisque firing (the
>slip is made from the same clay body as the pots), am I
>correct in thinking that this is a glaze fit problem? In other
>words, stress between glaze and clay expansion causing the
>slip trailed decoration to fracture?
>
>Or am I missing something more basic?
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
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