Jimmy G on sun 26 aug 01
I'm dying to replicate some of the colors/textures in the book "the
Potter's Palette."
From what I've been told, appearances at ^6 should be similar to the ^10
oxidation results (Especially if I increase the colorants).
I tried some of the combinations using a rather good base that I've had
luck with (found in Rhodes Glaze book), however the results were far
from what the samples in the book revealed.
My next shot is to try to duplicate the base glaze in "Palette," however
I am unclear about the difference between China Clay & Ball clay. Can
I substitute one for the other without any extreme variations in the
results as shown? I'm aware that there is always SOME variance when
components are varied (Or, for that matter, if I blink with my right eye
during mixing instead of my left).
I also intend to try to alter this glaze to a ^6, but that's another
story.
Any suggestions on this would be greatly appreciated. Also, if anybody
out there had had any luck with the above mentioned book, "Palette," I'd
love to hear from you.
BTW, I've checked on the Clayart archives & had minimal success with
these topics as applicable to my situation.
Thanx much
Paul Lewing on sun 26 aug 01
on 8/26/01 9:37 PM, Jimmy G at jsgreene@CTS.COM wrote:
> I am unclear about the difference between China Clay & Ball clay. Can
> I substitute one for the other without any extreme variations in the
> results as shown?
Hi, Jimmy.
There are some differences between ball clay and china clay (also known as
kaolin). Whether that will make a difference in the fired results or not
will vary.
The differences between the two clays are that ball clay has more iron, more
loss on ignition, and more shrinkage from wet to dry. These of course vary
with different brands of ball clay and china clay, but in general, these
differences apply.
The effects you might see because of these differences are:
Ball clay may make your clear or white glazes a yellowish color inn
oxidation. In a dark glaze, particularly one colored with iron, you may not
notice a difference.
The difference in loss on ignition, mostly caused by more organic matter in
ball clay, may mean that you need more weight of raw clay to get the
equivalent moles of alumina and silica that you'd get from kaolin. This is
probably not a big enough difference that you'd notice it, though.
The greater shrinkage of ball clay can mean that, in a glaze with a lot of
it, it may make your glaze crawl.
Of course, you will need to test to see if any of these things really do
make a practical or noticeable differeence in your results.
Happy testing,
Paul Lewing, Seattle
Ababi on mon 27 aug 01
Hello Jimmy.
Why I do not understand you. Is it my bad English or because I was a miser
and did not buy Hopper's book?
Why don't you send the recipe? Could be much better for medium understanding
people like me and some more?
Perhaps we tested a similar glazes ?
In ^6 we make great glazes but don't expect it to be like ^10!
Ababi Sharon
ababisharon@hotmail.com
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
----- Original Message -----
From: "Jimmy G"
To:
Sent: Sunday, August 26, 2001 11:37
Subject: Clay in Glazes
> I'm dying to replicate some of the colors/textures in the book "the
> Potter's Palette."
>
> From what I've been told, appearances at ^6 should be similar to the ^10
> oxidation results (Especially if I increase the colorants).
>
> I tried some of the combinations using a rather good base that I've had
> luck with (found in Rhodes Glaze book), however the results were far
> from what the samples in the book revealed.
>
> My next shot is to try to duplicate the base glaze in "Palette," however
> I am unclear about the difference between China Clay & Ball clay. Can
> I substitute one for the other without any extreme variations in the
> results as shown? I'm aware that there is always SOME variance when
> components are varied (Or, for that matter, if I blink with my right eye
> during mixing instead of my left).
>
> I also intend to try to alter this glaze to a ^6, but that's another
> story.
>
> Any suggestions on this would be greatly appreciated. Also, if anybody
> out there had had any luck with the above mentioned book, "Palette," I'd
> love to hear from you.
>
>
> BTW, I've checked on the Clayart archives & had minimal success with
> these topics as applicable to my situation.
>
> Thanx much
>
>
____________________________________________________________________________
__
> 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.
>
David Hewitt on mon 27 aug 01
Jimmy,
I would think that we have all experienced the problem you are finding -
someone's well tried recipe doesn't work as expected.
You ask about the difference between China clay and Ball clay. It can be
quite significant, depending on which ball clay you are talking about.
The following table illustrates the % analysis difference between four
Ball clays and a china clay as far as SiO2, Al2O3, other oxides and LOI
are concerned.
SiO2 Al2O3 Other Loss on
Oxides Ignition
BKS 74 17 4 5
HYPLAS 71 70 19 6 5
HVAR 63 25 5 7
TWVA 51 33 5 11
N 50 China clay 47 37 4 12
Quite apart from any other aspect of using a ball clay instead of china
clay, the analysis figures above show that these in themselves can be
significant should they form anything more than a small amount of the
recipe.
I do not have a copy of 'The Potters Palette' but, if it gives an
analysis for the recipe, this will help to if you wish to change one of
the raw materials and you have a glaze calculation program to help you.
As a very good example of a book giving many recipes is Mike Bailey's
new book 'Cone 6 Glazes'. In all cases he gives the analysis of each
recipe and the analysis of the raw materials that he has used.
'Transporting' recipes has many problems, not the least being the clay
body being used and often this information is not included with a
recipe. In recognising the problems of 'Transporting' recipes one can be
better prepared. If you are interested in my thoughts on this you can
see my web site under 'Pottery techniques' / 'Transporting Recipes'
http://www.dhpot.demon.co.uk
David
In message , Jimmy G writes
>My next shot is to try to duplicate the base glaze in "Palette," however
>I am unclear about the difference between China Clay & Ball clay. Can
>I substitute one for the other without any extreme variations in the
>results as shown? I'm aware that there is always SOME variance when
>components are varied (Or, for that matter, if I blink with my right eye
>during mixing instead of my left).
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Paul Taylor on wed 29 aug 01
Dear Jimmy
the difference between ball clay and china clay is
1 particle size; ball clays are of much smaller particle size to the extent
that you can consider ball clay as very plastic and china clay as not
plastic at all. The usual "however" is that there are some clays that are so
similar to china clay yet they are relatively plastic these are not usually
called ball clays but some people may call them such because they are not
china clays. complicated (sorry) because of the particle size ball clays
flux at a lower temperature than a china clay again every one is different
so i can not be specific. however the particle size will make a difference
to most matt glazes the extra fluxing changing the amount of nuclei
available to form crystals in the glaze. particle size also effects the way
the pot glazes.
2 ball clays have a different chemical analysis to china clays especially in
trace elements such as titanium and iron it is possible to get ball clays to
give a near enough approximation of all the other chemicals in china clay
except these two.
Since these materials cause very slight yellowing in oxidation and very
slight gray and/or green and/ or blue in reduction obviously you are not
going to be able to substitute ball clay for china in a clear or light
colored glaze but again that depends- you might get away with it. I have .
In a colored glaze or some matt glazes you can ( allowing for the extra
fluxing by lowering the kiln temperature.
You asked about cone six reduced bing an equivalent of cone ten oxidized
this depends on the amount of iron. there is a difference in the fluxing
action between reduced and oxidized iron and although the difference is
small it seems to make a big difference to all glazes. your suggested two
cones would be an extreme. I am sure that there are some iron containing
glazes that show that difference but the permutations are so complicated any
body stating a rule would be foolish. your best indication is to do draw
trials because when the glaze fluxes will make a lot of difference. one
reduction cycle will have more effect than another depending on whether you
are reducing just before the glazes melts in reduction or waiting for the
glaze to sinter a little in oxidation and then reducing. If you can get your
mind round that piece of logic you are a long way to understanding reduction
glazes but you can see there are a lot of permutations . so you can see one
of the reasons glazes do not travel.
There seems to be an unsated understanding that adjustment of the recipe
would compensate for any differences in a kiln firing . this to certain
extent is true but there are some glazes this will not work as it would be
an equivalent of trying to get ice cream to form at five degrees centigrade
by changing the milk content.
What drives the thinking is that it is easier to adjust a glaze than a
kiln schedule. you can fire fifty tests but only one test firing at a time
however if you are going to recreate those glazes you will have to come near
enough the original firing schedules - the cooling maybe more important than
the heating. A bit of detective work will do you what sort of bricks were
available at the time do you suspect the kiln was artificiality cooled and
remember quick cooling in 1930s brick kiln could be slow cooling in a fiber
kiln .
If the book is geared to the industrial process the receptionist will fire
well in a modern kiln.
All this makes glazes so much fun and there is the possibility for personal
nuances within your discoveries . The millions of permutations are on the
one hand exiting but on the other hand nerve wracking. Probably one of the
few sciences left for personal discovery.
From what i have said you may feel that you could have bitten off more than
you can chew. If you are a beginner to glazes and you need consistency for a
modern fast firing kiln I would use some one like Ron Roy as a mentor if his
book is out. I feel his methodologies would give a compleat understanding of
the chemistry which you would need before you could start mucking about with
firing schedules which are expensive. If you have a sound understanding of
formulas the glaze world is at your feet waiting to surprise you. Again I
repeat, draw trials are your only man - on heating and cooling.
Best of luck wi
Regards from Paul Taylor
http://www.anu.ie/westportpottery
Alchemy is the proof that economics is not a science.
> From: Jimmy G
> Reply-To: Ceramic Arts Discussion List
> Date: Sun, 26 Aug 2001 14:37:46 -0700
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Clay in Glazes
>
> I'm dying to replicate some of the colors/textures in the book "the
> Potter's Palette."
>
> From what I've been told, appearances at ^6 should be similar to the ^10
> oxidation results (Especially if I increase the colorants).
>
> I tried some of the combinations using a rather good base that I've had
> luck with (found in Rhodes Glaze book), however the results were far
> from what the samples in the book revealed.
>
> My next shot is to try to duplicate the base glaze in "Palette," however
> I am unclear about the difference between China Clay & Ball clay. Can
> I substitute one for the other without any extreme variations in the
> results as shown? I'm aware that there is always SOME variance when
> components are varied (Or, for that matter, if I blink with my right eye
> during mixing instead of my left).
>
> I also intend to try to alter this glaze to a ^6, but that's another
> story.
>
> Any suggestions on this would be greatly appreciated. Also, if anybody
> out there had had any luck with the above mentioned book, "Palette," I'd
> love to hear from you.
>
>
> BTW, I've checked on the Clayart archives & had minimal success with
> these topics as applicable to my situation.
>
> Thanx much
>
> ______________________________________________________________________________
> 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.
Craig Martell on tue 17 dec 02
Hi:
You guys need to stop putting all that clay in your glazes and save it for
making pots! OK, I'm just kidding.
There are some glazes that don't need a lot of clay and are really easier
to apply and use with very small amounts of clay or none at all. Would you
like an example? OK, fine, I'll go back to the Three Stooges film festival.
Some of the celadons that I use benefit from a low to zero clay
content. My reasoning is that I need to apply them very thick to get the
color. Clay increases the shrinkage of the glaze slop and cracking and
crawling my result. Actually, at the thickness I use for these glazes they
most always have problems with crawling.
The blue celadons that I've made have no clay at all. I keep them in
suspension by ball milling them for about an hour and also adding 3%
macaloid or another hectorite material called "hectabrite". The glazes
stay suspended very well and never settle out to a hard mass. The don't
contain Nepheline Syenite so I don't have to be concerned about long term
problems that arise from that stuff.
I'm trying some new formulas for the blue celadons and they are burning in
the kiln as I type. No clay in these either. So far, they've applied
flawlessly, dried overnight with nary a crack, so we'll see. I used 3%
Hectabrite in these celadons and it worked very well with regard to giving
the glaze a good, tough, non dusting surface.
If anyone is wondering, Hectabrite is manufactured from hectorite ore by
American Colloids.
regards, Craig Martell Hopewell, Oregon
Ababi on wed 18 dec 02
Thank you Craig, good to know, especially when I usually try to add clay to glazes.
Another low or calcined clay glaze is the crystal glaze. By the way about the hectorite:
http://webmineral.com/data/Hectorite.shtml
Ababi
---------- Original Message ----------
>Hi:
>You guys need to stop putting all that clay in your glazes and save it for
>making pots! OK, I'm just kidding.
>There are some glazes that don't need a lot of clay and are really easier
>to apply and use with very small amounts of clay or none at all. Would you
>like an example? OK, fine, I'll go back to the Three Stooges film festival.
>Some of the celadons that I use benefit from a low to zero clay
>content. My reasoning is that I need to apply them very thick to get the
>color. Clay increases the shrinkage of the glaze slop and cracking and
>crawling my result. Actually, at the thickness I use for these glazes they
>most always have problems with crawling.
>The blue celadons that I've made have no clay at all. I keep them in
>suspension by ball milling them for about an hour and also adding 3%
>macaloid or another hectorite material called "hectabrite". The glazes
>stay suspended very well and never settle out to a hard mass. The don't
>contain Nepheline Syenite so I don't have to be concerned about long term
>problems that arise from that stuff.
>I'm trying some new formulas for the blue celadons and they are burning in
>the kiln as I type. No clay in these either. So far, they've applied
>flawlessly, dried overnight with nary a crack, so we'll see. I used 3%
>Hectabrite in these celadons and it worked very well with regard to giving
>the glaze a good, tough, non dusting surface.
>If anyone is wondering, Hectabrite is manufactured from hectorite ore by
>American Colloids.
>regards, Craig Martell Hopewell, 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.
Ron Roy on fri 20 dec 02
Which brings up another aspect of glaze suspension. The thicker the glazes
are in the bucket - the easier it is to keep them suspended.
If your bisque is low fired then you need to have your glazes thinner to
get the "right" thickness when glazing. One way to improve glaze suspension
then is to bisque higher and skim some water off your glazes.
RR
Craig said -
>Some of the celadons that I use benefit from a low to zero clay
>content. My reasoning is that I need to apply them very thick to get the
>color. Clay increases the shrinkage of the glaze slop and cracking and
>crawling my result. Actually, at the thickness I use for these glazes they
>most always have problems with crawling.
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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