Val Schleicher on wed 3 aug 05
I have been using this glaze recipe for some time and just had my first
OH MY when I opened the kiln...I had re-calibrated by beam, its was perfect
as I started this new batch, glazed two kiln loads and Fired to 05,
Majolica
Frit 3124 2630gr
F4 Fieldspar 685.1
kaolin EPK 430.8
Neph Syn 250
Tin Oxcide 200
Bentonite 80
Zircopax 400
Iron oxcide 20
The Glaze has not melted, it is still whitish / pink with a powdery touch to
it. All the color oxcides melted perfectly, not the base majolica. The kiln
fired to temp. What could of went wrong? Can I fix this batch of glaze? Fix
the peices I have fired?
The only item new this time around was the bentonite I just ordered last
month. Wouldent you know I have a two day show this weekend and this was all
my new product.
HELP in hot wisconsin
Val
Val Schleicher on thu 4 aug 05
Just problem solving here, it is now apparent that Flint may of been
accidently added (about 1200 gr) as part of the frit 3124. Leaving only 1430
gms. of frit in the batch. (Two seperate conatianers mismarked, that won't
happen again)
That being a possibility can the glaze be fixed?
Will the fired tiles take an additional coating of a new batch of majolica?
Any takers here?
Still hot in Wisconsin even in the basement studio. New batch in the
process, busy day ahead.
Val
Lester Haworth on thu 4 aug 05
If you have not changed the glaze I would suspect the kiln. How did your
witness cones fire?
Les H.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Val
Schleicher
Sent: Wednesday, August 03, 2005 3:40 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Glaze problem: did not melt
I have been using this glaze recipe for some time and just had my first
OH MY when I opened the kiln...I had re-calibrated by beam, its was perfect
as I started this new batch, glazed two kiln loads and Fired to 05,
Majolica
Frit 3124 2630gr
F4 Fieldspar 685.1
kaolin EPK 430.8
Neph Syn 250
Tin Oxcide 200
Bentonite 80
Zircopax 400
Iron oxcide 20
The Glaze has not melted, it is still whitish / pink with a powdery touch to
it. All the color oxcides melted perfectly, not the base majolica. The kiln
fired to temp. What could of went wrong? Can I fix this batch of glaze? Fix
the peices I have fired?
The only item new this time around was the bentonite I just ordered last
month. Wouldent you know I have a two day show this weekend and this was all
my new product.
HELP in hot wisconsin
Val
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Karen Latorre on sat 6 aug 05
Hi Val,
I don't glaze fire to 05, but would suggest the following. Others, please
feel free to correct me if I've gone wrong somewhere as it is getting a bit
late.
Note that all values are in grams.
Mix up a couple of test batches as follows. I would do this just to
confirm your suspicions before you put any more effort into your existing
"bad batch". Fire both in your next glaze load.
a. your original recipe:
F3124 131.5
F4 34.3
EPK 21.5
Neph Sye 12.5
Tin Oxide 10
Bentonite 4
Zircopax 20
Red Iron Ox 1
b. the result of the mistake you believe was made
F3124 71.5
F4 34.3
EPK 21.5
Neph Sye 12.5
Tin Oxide 10
Bentonite 4
Zircopax 20
Red Iron Ox 1
Flint 60
Following is the report from Insight on versions a and b above:
Two Recipes: Val: Untitled Recipe 1 & : What Was Mixed By Mistake
=================================================================
F3124............... 2630.00 1430.00
F4 SPAR............. 685.10 685.10
EPK................. 430.80 430.80
NEPH SY............. 250.00 250.00
TIN................. 200.00 200.00
BENTONITE........... 80.00 80.00
*zircopax............ 400.00 400.00
RED IRON OX......... 20.00 20.00
*flint............... 1200.00
======== ========
4695.90 4695.90
CaO 0.41* 0.39*
MgO 0.00* 0.01*
K2O 0.04* 0.06*
Na2O 0.23* 0.27*
Fe2O3 0.01 0.02
TiO2 0.00 0.00
B2O3 0.31* 0.28*
Al2O3 0.37 0.50
SiO2 2.31 2.74
P2O5 0.00 0.00
SnO2 0.08 0.13
COST/KG 4.37 4.81
Si:Al 6.22 5.46
SiB:Al 7.06 6.02
EXPAN518.23 501.34
MDT: C:\INSIGHT5.X\RONROY.TMT
If your suspicions were correct, and what you now have is glaze B above,
then following is one suggestion for correction. First I'm enclosing the
recipe for a test batch for you to try as I have found that recalculating
essentially the same Unity Formula with different materials can result in
very different glazes (as I have found that the nature of the raw materials,
i.e. mother nature's frits such as the various feldspars versus man made
"pure" materials, and the mesh size of each material plays a significant
part in the final glaze).
c. new Majolica (cone 05)
F3124 83.5
F4 21.3
EPK 13.6
Neph Sye 5.5
Tin Oxide 6.5
Bentonite 6
Zircopax 20
Red Iron Ox 0.7
Flint 60
F3124............... 83.50
F4 SPAR............. 21.30
EPK................. 13.60
NEPH SY............. 5.50
TIN................. 6.50
BENTONITE........... 6.00
*zircopax............ 20.00
RED IRON OX......... 0.70
*flint............... 60.00
========
217.10
CaO 0.41*
MgO 0.01*
K2O 0.04*
Na2O 0.23*
Fe2O3 0.01
TiO2 0.00
B2O3 0.31*
Al2O3 0.37
SiO2 2.32
P2O5 0.00
SnO2 0.08
COST/KG 4.47
Si:Al 6.22
SiB:Al 7.06
EXPAN510.65
MDT: C:\INSIGHT5.X\RONROY.TMT
If this test batch works for you, you'll have to figure out how much of
the bad batch you have left before you can decide what needs to be added.
For the purpose of this response, I'll assume you have pretty much the
original amount of glaze (i.e. you've only glazed and fired one small pot as
a test of the new batch), then you'd want to add the following to your
existing bad batch. Note that this leaves you with a rather LARGE pile of
glaze, so you'll want to really test the new glaze above, before you proceed
down this path (otherwise you're just chucking more good raw materials into
a bad batch).
CURRENT BAD BATCH EXTRA TO ADD NEW MAJOLICA
F3124 1430 2365.5 3795.5
F4 685.1 283.1 968.2
EPK 430.8 187.4 618.2
Neph Sye 250 0 250
Tin Oxide 200 95.5 295.5
Bentonite 80 192.7 272.7
Zircopax 400 509.1 909.1
Red Iron Ox 20 11.8 31.8
Flint 1200 1527.3 2727.3
Alternatively, you can add some more Si and Al (i.e. clay and possibly more
flint) and use it as a Cone 6 glaze.
As for correcting pots that already have this glaze on them, as I would
imagine you've used a low fire clay, so you can't fire them higher to
achieve the melt therefore I don't really have the only suggestion would be
to add a glaze that fires even lower than 05 to the tiles (and I wouldn't
know what to suggest here - perhaps one of the frits melts this low?).
Hope this helps a bit,
Karen Latorre
www.karenlatorre.com (last updated July 15, 2005)
just north of Belleville, Ontario
first spam received Aug 4, 24 days from first posting on Clayart. So much
for the spam free email account.
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Ron Roy on sat 6 aug 05
Hi Val,
Sounds like you left out the frit - thats the main melter in this glaze.
I think you asked if you could save it if you had added silica instead of
frit - if the glaze had enough silica in it - it would be possible to make
a counter batch - leaving out the silica and adding twice as much frit -
if there was enough silica to start with - but I can't see how to do it -
no silica in the original.
RR
>I have been using this glaze recipe for some time and just had my first
>OH MY when I opened the kiln...I had re-calibrated by beam, its was perfect
>as I started this new batch, glazed two kiln loads and Fired to 05,
>
>Majolica
>Frit 3124 2630gr
>F4 Fieldspar 685.1
>kaolin EPK 430.8
>Neph Syn 250
>Tin Oxcide 200
>Bentonite 80
>Zircopax 400
>Iron oxcide 20
>
>The Glaze has not melted, it is still whitish / pink with a powdery touch to
>it. All the color oxcides melted perfectly, not the base majolica. The kiln
>fired to temp. What could of went wrong? Can I fix this batch of glaze? Fix
>the peices I have fired?
>
>The only item new this time around was the bentonite I just ordered last
>month. Wouldent you know I have a two day show this weekend and this was all
>my new product.
>HELP in hot wisconsin
>Val
>
>______________________________________________________________________________
>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.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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