Nanci Bishof on mon 1 jan 01
Marion,
I use it as a slip or straight when I work in porcelain. I don't get
separation of the joints. I think you'll like it.
nanci
Tom Buck on mon 1 jan 01
A note on putting handles on mugs, etc.
Here is my take on the question, and it is of course subject to
general review and criticism, as usual (are you there Will E?)
A major problem in doing joins of clay pieces is the differential
moisture content of the two pieces, usually the mug has dried a bit more
than the handle.
Vinegar supplies hydrogen ion (H+ ion), and this highly mobile ion
will cause agglomeration of clay particles ("flocculation"). If you put
the vinegar on the handle end, the particles stick to themselves in the
handle and won't intermingle with particles on the mug to make a uniform
joint, just as if it grew out of the mug itself.
Vinegar is especially useful with porcelain because its components
(feldspar, flint/silica, china clay/kaolin, ballclay/pyrophyllite/kyanite)
tend to segregate into "zones" when the surface is rewetted; the H+ ion
minimizes this effect.
To do good joins, mix a coffee-cream slip (claybody+vinegar), and
apply it generously to both mug and handle, then hold the handle in place
for up to 30 seconds to allow good intermingling of the two portions of
the piece.
Martin Howard wonders why the late Robert Fournier said not to use
vinegar when making joints that would be almost immediately under
strain/stress because the joints would soon fail. Martin says Fournier
never explained his reasoning. The simplest explanation of Fournier's view
(as a teacher) is that good joins are not easy to do, and he was warning
the uninitiated away from this trouble.
be well Happy New Year. Peace. Tom B.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
Rod, Marian, and Holly Morris on mon 1 jan 01
Here's another vinegar question:
I have always used it, and like it, just painting it on straight, no slip.
BUT recently I did make a slip of vinegar and the clay and got a very stinky
hydrogen sulfide smell (rotten eggs), and my slip did bubble up and get not
only stiffer, but a peculiar texture which was not very malleable.
Reading about how the acid reacts with the calcium. I can see how this
happened. But my question is, if its the reactive hydrogen in the vinegar
that helps the join, then aren't we neutralizing that when we mix up a slip
with it before applying it to the join?
I am very interested in this discussion, because I am moving to porcelain,
and know of its propensity to not like to join well.
Thanks Marian in Michigan
----- Original Message -----
From: "Tom Buck"
To:
Sent: Monday, January 01, 2001 1:15 PM
Subject: Joining handles
> A note on putting handles on mugs, etc.
> Here is my take on the question, and it is of course subject to
> general review and criticism, as usual (are you there Will E?)
> A major problem in doing joins of clay pieces is the differential
> moisture content of the two pieces, usually the mug has dried a bit more
> than the handle.
> Vinegar supplies hydrogen ion (H+ ion), and this highly mobile ion
> will cause agglomeration of clay particles ("flocculation"). If you put
> the vinegar on the handle end, the particles stick to themselves in the
> handle and won't intermingle with particles on the mug to make a uniform
> joint, just as if it grew out of the mug itself.
> Vinegar is especially useful with porcelain because its components
> (feldspar, flint/silica, china clay/kaolin, ballclay/pyrophyllite/kyanite)
> tend to segregate into "zones" when the surface is rewetted; the H+ ion
> minimizes this effect.
> To do good joins, mix a coffee-cream slip (claybody+vinegar), and
> apply it generously to both mug and handle, then hold the handle in place
> for up to 30 seconds to allow good intermingling of the two portions of
> the piece.
> Martin Howard wonders why the late Robert Fournier said not to use
> vinegar when making joints that would be almost immediately under
> strain/stress because the joints would soon fail. Martin says Fournier
> never explained his reasoning. The simplest explanation of Fournier's view
> (as a teacher) is that good joins are not easy to do, and he was warning
> the uninitiated away from this trouble.
>
> be well Happy New Year. Peace. Tom B.
> Tom Buck ) tel: 905-389-2339
> (westend Lake Ontario, province of Ontario, Canada).
> mailing address: 373 East 43rd Street,
> Hamilton ON L8T 3E1 Canada
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
| |
|
