Matthew Rosenberg on wed 6 jan 99
Have a problem with a frit based glaze that melts and performs well at
the required temp but is difficult to apply to the bisque. After
dipping the surface is literally bumpy. I did not seem to have the
problem when I have used only Ferro 3124 and clay. The problem formula
is for Orton cone 04-03:
36.5% 3124
36.5% 3134
22.5% EPK
4.5% Silica
I opacify this glaze heavily with around 20% zircopax for a crisp suface
for majolica decoration. The bisque is fired to around Orton cone 06
but I have tried bisqing at higher with the same sort of results. If
3124 and EPK are used I have an expansion problem but absolutely no
application problem with exactly the same amount of opacifier. I
normally do not add anything to the white except about 1% bentonite
because the zircopax gives the glaze a nice creamy consistency (in the
bucket at least). The moment I shift the recipe to 3134 to adjust for
shivering caused by the zircopax I encounter this bumpy application
problem. Tried using epsom salts, gums, thinners but nothing seems to
work. Any ideas?
Thanks. Matthew
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Jonathan Kaplan on thu 7 jan 99
>----------------------------Original message----------------------------
>Have a problem with a frit based glaze that melts and performs well at
>the required temp but is difficult to apply to the bisque. After
>dipping the surface is literally bumpy. I did not seem to have the
>problem when I have used only Ferro 3124 and clay. The problem formula
>is for Orton cone 04-03:
>36.5% 3124
>36.5% 3134
>22.5% EPK
>4.5% Silica
>I opacify this glaze heavily with around 20% zircopax for a crisp suface
>for majolica decoration. The bisque is fired to around Orton cone 06
>but I have tried bisqing at higher with the same sort of results. If
>3124 and EPK are used I have an expansion problem but absolutely no
>application problem with exactly the same amount of opacifier. I
>normally do not add anything to the white except about 1% bentonite
>because the zircopax gives the glaze a nice creamy consistency (in the
>bucket at least). The moment I shift the recipe to 3134 to adjust for
>shivering caused by the zircopax I encounter this bumpy application
>problem. Tried using epsom salts, gums, thinners but nothing seems to
>work. Any ideas?
>Thanks. Matthew
>
>______________________________________________________
>Get Your Private, Free Email at http://www.hotmail.com
Take your bisque to cone 04. You may need to adjust your glaze rheology for
appplication to a higher bisque. You shivering is the result of the too low
an expansion of the glaze. You could also cut the zirc back to 10% and be
happy with the surface. 20% zirc in my opinion is overkill.
Good luck
Jonathan
Jonathan Kaplan, president
Ceramic Design Group LTd/Production Services
PO Box 775112
Steamboat Springs, CO 80477
(970) 879-9139 voice and fax
http://www.sni.net/ceramicdesign
Jim Brooks on thu 7 jan 99
Matt.... usually, you can add up to 2% to most glazes with minimal, if any,
affect.. Try adding another 1% to a test batch ( for a total of 2%) and see if
that will help.. I have had it make a big difference in application for a
couple of glazes.........
Ron Roy on thu 7 jan 99
Hi Matt,
I need to have the recipe with only the 3124. What needs to be done is
raise the expansion of the glaze. This should be done on a molecular level
so the basic look of the glaze remains the same - and tell me what feldspar
you have - Custer or G200.
>----------------------------Original message----------------------------
>Have a problem with a frit based glaze that melts and performs well at
>the required temp but is difficult to apply to the bisque. After
>dipping the surface is literally bumpy. I did not seem to have the
>problem when I have used only Ferro 3124 and clay. The problem formula
>is for Orton cone 04-03:
>36.5% 3124
>36.5% 3134
>22.5% EPK
>4.5% Silica
>I opacify this glaze heavily with around 20% zircopax for a crisp suface
>for majolica decoration. The bisque is fired to around Orton cone 06
>but I have tried bisqing at higher with the same sort of results. If
>3124 and EPK are used I have an expansion problem but absolutely no
>application problem with exactly the same amount of opacifier. I
>normally do not add anything to the white except about 1% bentonite
>because the zircopax gives the glaze a nice creamy consistency (in the
>bucket at least). The moment I shift the recipe to 3134 to adjust for
>shivering caused by the zircopax I encounter this bumpy application
>problem. Tried using epsom salts, gums, thinners but nothing seems to
>work. Any ideas?
>Thanks. Matthew
>
>______________________________________________________
>Get Your Private, Free Email at http://www.hotmail.com
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
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