C TRIPP on thu 20 dec 01
'Morning,
Some time ago, Craig Martell posted his revision of Berry Rust, ^6ox. It's
an iron red which works well for me EXCEPT it crawls here and there; but not
in any thick places. I fire a long slow bisque to ^06. My hands and the pots
are clean before glazing. I do not fire the glazes "wet". I hold for 45-60
minutes at the top for a classic ^6 and I fire down at no more than 50C/hour
until 700C. Oh, and I use Tucker's Mid Red and Smooth White clays.
I had read on Clayart ages ago something Paul Lewing learned from Louis Katz
(?)to cure crawling; draw off all the water from a crawling glaze. Mix in
lots of fresh water, let it sit, draw the water off again, and so on for
several rounds. Well, the glaze still crawls but now it looks different and
not nice. Before it was a glossy sparkly iron rusty pink/red breaking dark
brown.
After the draining, it is just a brown.
So, did I drain off something crucial and can it be added back? Or would it
be best to start over (dumping the batch to the Browns bucket) and try to
fix the crawling some other way? I was thinking of calcining half the EPK
because I read that bone ash is a shrinker and that can cause crawling and I
figured if the EPK is shrinking too and if I calcine it...then I don't have
to start reducing the bone ash.
But now I am reading Ron Roy saying that subing a clay with a higher MOR
would be better. That being the case, would Om #4 at 850 MOR be better to
use than Bell Dark Ball at 690? But why does Ron Roy use this one the most?
I have to admit that when I first made this, I did use 17 EPK and 6 OM #4
and it crawled. Then I re tested with the orginal 23 EPK and it still
crawled but it was redder and I prefered the colour. That is, until I
drained something good away and it became brown.
Craig Martell's Berry Rust (rounded up) ^6ox
silica 24
EPK 23
nepheline syenite 9
bone ash 9
talc 15
frit 3134 20
Red Iron Oxide 8.5%
(INSIGHT)
CaO 0.47
MgO 0.37
K2O 0.02
Na2O 0.14
TiO2 0.00
Al2O3 0.31
B203 0.19
P2O5 0.08
Si2O3 2.88
Fe2O3 0.16
Si:Al 9.28
Expan: 6.48
This is such a lovely glaze. It passes the 3 day vinegar test and the
freeze/boiling water shock test. If only I could stop the little crawls...
Thanks for your help.
Best regards,
Carol
PS and thanks to Craig Martell for the revision
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Christena Schafale on thu 20 dec 01
Carol,
Calcine some of the clay. It won't change the glaze composition, and it
probably will solve the problem. I would recommend leaving 12-15% raw and
calcining the rest.
Chris
At 05:07 AM 12/20/01 -0800, you wrote:
>'Morning,
>Some time ago, Craig Martell posted his revision of Berry Rust, ^6ox. It's
>an iron red which works well for me EXCEPT it crawls here and there; but not
>in any thick places. I fire a long slow bisque to ^06. My hands and the pots
>are clean before glazing. I do not fire the glazes "wet". I hold for 45-60
>minutes at the top for a classic ^6 and I fire down at no more than 50C/hour
>until 700C. Oh, and I use Tucker's Mid Red and Smooth White clays.
>
>I had read on Clayart ages ago something Paul Lewing learned from Louis Katz
>(?)to cure crawling; draw off all the water from a crawling glaze. Mix in
>lots of fresh water, let it sit, draw the water off again, and so on for
>several rounds. Well, the glaze still crawls but now it looks different and
>not nice. Before it was a glossy sparkly iron rusty pink/red breaking dark
>brown.
>After the draining, it is just a brown.
>
>So, did I drain off something crucial and can it be added back? Or would it
>be best to start over (dumping the batch to the Browns bucket) and try to
>fix the crawling some other way? I was thinking of calcining half the EPK
>because I read that bone ash is a shrinker and that can cause crawling and I
>figured if the EPK is shrinking too and if I calcine it...then I don't have
>to start reducing the bone ash.
>
>But now I am reading Ron Roy saying that subing a clay with a higher MOR
>would be better. That being the case, would Om #4 at 850 MOR be better to
>use than Bell Dark Ball at 690? But why does Ron Roy use this one the most?
>
>
>I have to admit that when I first made this, I did use 17 EPK and 6 OM #4
>and it crawled. Then I re tested with the orginal 23 EPK and it still
>crawled but it was redder and I prefered the colour. That is, until I
>drained something good away and it became brown.
>
>
>
>Craig Martell's Berry Rust (rounded up) ^6ox
>silica 24
>EPK 23
>nepheline syenite 9
>bone ash 9
>talc 15
>frit 3134 20
>Red Iron Oxide 8.5%
>
>(INSIGHT)
>CaO 0.47
>MgO 0.37
>K2O 0.02
>Na2O 0.14
>TiO2 0.00
>Al2O3 0.31
>B203 0.19
>P2O5 0.08
>Si2O3 2.88
>Fe2O3 0.16
>
>Si:Al 9.28
>Expan: 6.48
>
>This is such a lovely glaze. It passes the 3 day vinegar test and the
>freeze/boiling water shock test. If only I could stop the little crawls...
>Thanks for your help.
>Best regards,
>Carol
>PS and thanks to Craig Martell for the revision
>
>
>
>
>
>______________________________________________________________________________
>Send a friend your Buddy Card and stay in contact always with Excite Messenger
>http://messenger.excite.com
>
>______________________________________________________________________________
>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.
Consultation and Referral Specialist
Resources for Seniors
christenas@rfsnc.org
www.resourcesforseniors.com
Phone: (919) 713-1537
FAX: (919) 872-9574
1110 Navaho Dr, Suite 400
Raleigh, NC 27609
Craig Martell on thu 20 dec 01
Hi:
If it's a raw shrinkage problem, calcining some of the EPK should stop the
trouble. At 23%, there's a pretty fair chance that this really is the problem.
I figured the LOI of EPK kaolin at 13.91%. Leave all the other percentages
in the glaze alone and use raw EPK at 12% and calcined EPK at 12.5%.
To calcine the EPK, just fire it to about 1500 F and then add it to the
glaze by weight. I use bisque fired bowls to calcine clays and other raw
materials. I fill the bowls and then put a crater in the center of the
pile for better heat distribution.
If this doesn't solve the probelm, lemme know.
regards, Craig Martell in Oregon
Christena Schafale on fri 21 dec 01
Wait a minute! If you calcine the EPK, then weigh it out for your glaze,
you should be ending up with a total that is LESS than what you started
with, not more! With 12% raw EPK, the other 11%, calcined, will actually
be around 9.5% using your figure for LOI.
Chris
At 02:46 PM 12/20/01 -0800, you wrote:
>Hi:
>
>If it's a raw shrinkage problem, calcining some of the EPK should stop the
>trouble. At 23%, there's a pretty fair chance that this really is the
>problem.
>
>I figured the LOI of EPK kaolin at 13.91%. Leave all the other percentages
>in the glaze alone and use raw EPK at 12% and calcined EPK at 12.5%.
>
>To calcine the EPK, just fire it to about 1500 F and then add it to the
>glaze by weight. I use bisque fired bowls to calcine clays and other raw
>materials. I fill the bowls and then put a crater in the center of the
>pile for better heat distribution.
>
>If this doesn't solve the probelm, lemme know.
>
>regards, Craig Martell in Oregon
>
>______________________________________________________________________________
>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.
Consultation and Referral Specialist
Resources for Seniors
christenas@rfsnc.org
www.resourcesforseniors.com
Phone: (919) 713-1537
FAX: (919) 872-9574
1110 Navaho Dr, Suite 400
Raleigh, NC 27609
Craig Martell on fri 21 dec 01
Chris gasped:
>Wait a minute! If you calcine the EPK, then weigh it out for your glaze,
>you should be ending up with a total that is LESS than what you started
>with, not more!
Hi:
Yes, exactly right unless you're not paying attention to what you're
doing. Thanks for pointing out my error. I added when I should have been
subtracting but you've already pointed that out. I'm glad someone is awake.
regards, Craig Martell in Oregon
Ron Roy on mon 24 dec 01
Good questions Carol,
Here is my revision using OM#4 - be happy to do one with Bell Dark as well
if you want to test both.
You have to remember - you need more ball to replace any kaolin to get the
same amount of alumina - which is probably necessary in this glaze.
Silica - 18.0
OM#4 - 31.0
Neph Sy - 8.0
Bone Ash - 9.0
Talc - 14.5
F3134 - 19.5
Red iron - 8.5
Total - 108.5
I just calculated subbing in Bell dark for OM#4 - just use the above recipe
with Bell dark instead of OM#4 - they are almost identical in chemistry.
Why I use Bell Dark instead of OM#4. Long story but the essentials are -
Bell is a more stable clay. As you may know Tuckers tests raw materials as
they arrive so I have data going back at least 15 years on the Bell clay
and it very stable in shrinkage and absorbency. OM#4 is less so and never
as plastic as the Bell. The Bell is more reliable for making clay and more
plastic.
I just got used to using the Bell dark and Tuckers had it in stock.
You are right OM#4 has a dry MOR of 825 (different set of data from the
mine - and Bell has a dry MOR of 690. The data I have for EPK says it has a
dry MOR of 300.
Just to give some other comparisons of KT clays:
Todd Dark - Dry MOR - 1000
M&D - Dry MOR - 1750 ( has 2.3 iron - rest have approx 1.0 iron)
Tennessee#5 - Dry MOR - 400
KT#1 - Dry MOR 500
they also have two kaolins that look interesting
Rogers - Dry MOR - 970
Samson - Dry MOR - 960.
Let us know if they work please - any questions?
RR
>But now I am reading Ron Roy saying that subing a clay with a higher MOR
>would be better. That being the case, would Om #4 at 850 MOR be better to
>use than Bell Dark Ball at 690? But why does Ron Roy use this one the most?
>
>
>I have to admit that when I first made this, I did use 17 EPK and 6 OM #4
>and it crawled. Then I re tested with the orginal 23 EPK and it still
>crawled but it was redder and I prefered the colour. That is, until I
>drained something good away and it became brown.
>
>
>
>Craig Martell's Berry Rust (rounded up) ^6ox
>silica 24
>EPK 23
>nepheline syenite 9
>bone ash 9
>talc 15
>frit 3134 20
>Red Iron Oxide 8.5%
>
>(INSIGHT)
>CaO 0.47
>MgO 0.37
>K2O 0.02
>Na2O 0.14
>TiO2 0.00
>Al2O3 0.31
>B203 0.19
>P2O5 0.08
>Si2O3 2.88
>Fe2O3 0.16
>
>Si:Al 9.28
>Expan: 6.48
>
>This is such a lovely glaze. It passes the 3 day vinegar test and the
>freeze/boiling water shock test. If only I could stop the little crawls...
>Thanks for your help.
>Best regards,
>Carol
>PS and thanks to Craig Martell for the revision
>
>
>
>
>
>______________________________________________________________________________
>Send a friend your Buddy Card and stay in contact always with Excite Messenger
>http://messenger.excite.com
>
>______________________________________________________________________________
>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 Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
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