Edouard Bastarache on mon 19 aug 02
Good evening Edouard,
You may transmit this to Clayart if you wish:=20
Fara says right in connection with the conservation of crystalline =
glazes. I myself made the report of this degradation with certain =
recipes rigorously prepared (weighed to 0.05 g.) and applied with equal =
density and weight to the same parts and fired in the same manner but =
used after different periods of conservation in the wet phase
I allot this behavior to the strong alkalinity of the high sodium frit =
used and to the fineness of particles. I think that the frit reacts =
quickly to leaching causing a setting in solution of the alkali which =
combines with other elements of the glaze by hydrolysis and thus =
opposing crystallization by inhibition of the " min=E9ralisateurs " =
(formation of crystal nuclei).=20
One can measure this degradation by mixing the glaze with distilled =
water, then by measuring at with regular intervals (every day for =
example) the conductivity of the water of the glaze (with a pocket =
conductivimeter). Conductivity increases regularly until it becomes =
stabilized (when the solution is balanced).=20
Thus a glaze applied the very same day of its preparation will be able =
to give rise to a great number of crystals, then a few days later it =
will be able to give only some of them.=20
The observation on the nature of the containers has also appeared to =
me.I prepare my glazes in small plastic jars and those take care of =
static electricity during crushing which does not happen with glass =
jars. I think that this phenomenon plays a role in the degradation of =
crystalline glazes.=20
Remedy: To prepare glazes in small amounts and to use them at once (for =
those which present this defect the most).=20
Cordially, Smart.=20
Smart.Conseil
Le site Fran=E7ais d=E9di=E9 aux passionn=E9s de c=E9ramique
The French site dedicated to ceramics lovers
smart2000@wanadoo.fr
http://perso.wanadoo.fr/smart2000/
(Langue Fran=E7aise par d=E9faut : Tutoiement =E0 la "Qu=E9b=E9coise")
Philip Poburka on mon 19 aug 02
As a simple pragmatic, could the Alcalinity be addressed with an addition of
some acid influence, as Vinegar, Lemon Juice, or something, or perhaps even
adding some Sugar as well?
If the Alcalinity is the means of the degredation of the Crystal manifesting
qualities, should the opposite ph encourage larger Crystals, or a more
stable shelf life for the Glaze?
Or...?
Just wonderin'...
Phil
Las Vegas...
----- Original Message -----
From: "Edouard Bastarache"
To:
Sent: Monday, August 19, 2002 3:38 PM
Subject: Crystal glazes going bad according to Smart
Good evening Edouard,
You may transmit this to Clayart if you wish:
Fara says right in connection with the conservation of crystalline glazes. I
myself made the report of this degradation with certain recipes rigorously
prepared (weighed to 0.05 g.) and applied with equal density and weight to
the same parts and fired in the same manner but used after different periods
of conservation in the wet phase
I allot this behavior to the strong alkalinity of the high sodium frit used
and to the fineness of particles. I think that the frit reacts quickly to
leaching causing a setting in solution of the alkali which combines with
other elements of the glaze by hydrolysis and thus opposing crystallization
by inhibition of the " minéralisateurs " (formation of crystal nuclei).
One can measure this degradation by mixing the glaze with distilled water,
then by measuring at with regular intervals (every day for example) the
conductivity of the water of the glaze (with a pocket conductivimeter).
Conductivity increases regularly until it becomes stabilized (when the
solution is balanced).
Thus a glaze applied the very same day of its preparation will be able to
give rise to a great number of crystals, then a few days later it will be
able to give only some of them.
The observation on the nature of the containers has also appeared to me.I
prepare my glazes in small plastic jars and those take care of static
electricity during crushing which does not happen with glass jars. I think
that this phenomenon plays a role in the degradation of crystalline glazes.
Remedy: To prepare glazes in small amounts and to use them at once (for
those which present this defect the most).
Cordially, Smart.
Smart.Conseil
Le site Français dédié aux passionnés de céramique
The French site dedicated to ceramics lovers
smart2000@wanadoo.fr
http://perso.wanadoo.fr/smart2000/
(Langue Française par défaut : Tutoiement à la "Québécoise")
____________________________________________________________________________
__
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.
| |
|
