Zoe Paddy Johnson on wed 25 jun 03
My two kids are both geologists. One is a grad student, the other an
undergrad. They were both previously art majors, the grad student having
seriously contemplated ceramics as a major. They both gave up art because
it wasn't quantitative enough.
Anyway, they heard about someone making glaze from the local granite and
were thrilled by the concept, so out came out the rock tumbler and we
scooped up a hubcap full of "grus" or the crumbled stuff at the base of an
outcrop. The stuff has been running along with a bunch of Mexican marbles
for nearly a month now. There were two types of marbles, some chinese
checker style solid color marbles and some regular catseye marbles. The
chinese checker marbles are really reduced in size after a month (the
diameter maybe as much as half of what they were). The catseye marbles
don't seem to have changed much in size. My daughter the geology/ceramics
student says this is good because we are adding silica to to the glaze. I
am worried we will have conflicting coloring agents, in glass,
yellow=cadmium and blue=sulfides, so yellow+blue=cadmium sulfide=yucky
*strong* black. But assuming that we are not totally whacked by the color,
what else do I need to add to get a glaze? We have a slurry the
consistency of cream right now. The kid tossed in about a tablespoon of
kitty litter when we loaded the tumbler.
After this experiment, they intend to try Jemez Caldera Volcanic ash and,
then, other geologic debris from interesting field trip locations...
So far we have learned:
1) use catseye marbles
Zoe Paddy Johnson on thu 26 jun 03
Cheap marbles are almost entirely a third world product at this point.
There are collector marbles produced out of glass like pyrex in the US, but
the average bag of marbles is from China or Mexico these days. The glass
in even marbles from the same factory is pretty variable with wildly
varying COE's. I think whatever was used as an opacifier in the Chinese
Checker marbles also made the marbles soft. I used to be a glass artist
and so had a bunches of bags of cheap marbles around. They were handy so I
grabbed them. I picked the chinese checker marbles because they were ugly.
I am pretty sure the catseye marbles are made of tougher stuff as they are
near their original diameter.
I will calcine the granite next time. The grus is the granite crumbles.
The pieces we put in were all about a .25 inch or smaller. It made it thru
the hardware cloth. I have no idea why the kitty litter got tossed in. It
just seemed like a good idea to the "tame" geologists.
My idea is to next time use only the shooters from the bags of catseye
marbles. They are bigger and tough. And Jemez volcanic ash crumbles much
better than granite.
Right now since we have something creamy and much of the grus and marbles
are gone, I am tempted to strain it, add wood ash and whatever else is
suggested and let 'er rip.
--On Friday, June 27, 2003 12:58 AM +0100 Janet Kaiser
wrote:
> The glass used for marbles is surely more like Pyrex these days? That
> could be one reason that they are still whole and not already completely
> pulverised.
>
> But I am not certain why you have added glass marbles and clay to your
> granite mix? Is that really a good idea? I only ask, because it seems to
> me you are adding yet more variables that you will not be able to
> reproduce in any resultant "wonder glaze" AND granite would surely not
> need any addition of silica or clay?
>
> I have recently been advised by various Clay buddies, that granite is easy
> to grind or mill, BUT only after it has been calcined. It is going to take
> you forever simply tumbling away, if it is anything like the granite we
> have here in Wales!
>
> I believe that no matter where the granite is from, it already has a high
> silica content... around 75%? It also contains 10-15 % alumina and various
> other constituents with up to 3% iron... So my best advice would be to
> first calcine some granite "chips" and then grind/mill it before going on
> to do some tests. If your tame geologists could get an analysis of the
> local granite you are using, you would be at an even greater advantage and
> be better able to work out a glaze in theory, before putting it into
> practice.
>
> Just using milled granite on its own (without those other clay and glass
> marble additives) will also lead to more consistency in your tests.
>
> I am sure rockers like Tony C. and Hank M. will be able to advise you
> more... This is just my tuppence worth!
>
> Janet Kaiser
> **********************************************************************
> TRUTH is too precious to tell every fool who asks for it...
> ****** This post was sent to you today by Janet Kaiser *******
> The Chapel of Art / Capel Celfyddyd
> 8 Marine Crescent, Criccieth LL52 0EA, Wales, UK
> Tel: ++44 (01766) 523570 URL: http://www.the-coa.org.uk
> **********************************************************************
>
> _________________________________________________________________________
> _____ 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.
Earl Brunner on thu 26 jun 03
Making porcelain balls and high firing them is a good idea, another
thing I've heard works well is to calcine the granite first. It will
mill easier or faster.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Louis Katz
Sent: Thursday, June 26, 2003 8:41 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: granite glaze for geologists
The glass is probably softer than the granite. Try using granite as
grinding media or maybe hard fired porcelain balls.
Granite has quartz crystals in it which are hard, mica, and feldspar.
The feldspar will grind first. The grus may already have hadd some of
the feldspar leached out of it. Because of the three minerals you may
find granite very hard to grind well.
Louis
Louis Katz on thu 26 jun 03
The glass is probably softer than the granite. Try using granite as
grinding media or maybe hard fired porcelain balls.
Granite has quartz crystals in it which are hard, mica, and feldspar.
The feldspar will grind first. The grus may already have hadd some of
the feldspar leached out of it. Because of the three minerals you may
find granite very hard to grind well.
Louis
On Wednesday, June 25, 2003, at 11:10 PM, Zoe Paddy Johnson wrote:
> My two kids are both geologists. One is a grad student, the other an
> undergrad. They were both previously art majors, the grad student
> having
> seriously contemplated ceramics as a major. They both gave up art
> because
> it wasn't quantitative enough.
>
> Anyway, they heard about someone making glaze from the local granite
> and
> were thrilled by the concept, so out came out the rock tumbler and we
> scooped up a hubcap full of "grus" or the crumbled stuff at the base
> of an
> outcrop. The stuff has been running along with a bunch of Mexican
> marbles
> for nearly a month now. There were two types of marbles, some chinese
> checker style solid color marbles and some regular catseye marbles.
> The
> chinese checker marbles are really reduced in size after a month (the
> diameter maybe as much as half of what they were). The catseye marbles
> don't seem to have changed much in size. My daughter the
> geology/ceramics
> student says this is good because we are adding silica to to the
> glaze. I
> am worried we will have conflicting coloring agents, in glass,
> yellow=cadmium and blue=sulfides, so yellow+blue=cadmium sulfide=yucky
> *strong* black. But assuming that we are not totally whacked by the
> color,
> what else do I need to add to get a glaze? We have a slurry the
> consistency of cream right now. The kid tossed in about a tablespoon
> of
> kitty litter when we loaded the tumbler.
>
> After this experiment, they intend to try Jemez Caldera Volcanic ash
> and,
> then, other geologic debris from interesting field trip locations...
>
> So far we have learned:
> 1) use catseye marbles
>
> _______________________________________________________________________
> _______
> 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.
>
iandol on fri 27 jun 03
Dear Zoe Paddy Johnson,=20
May I suggest you look for a slim volume entitled "Rock Glazes" by Ivan =
Englund ISBN 0-9591764-0-3.
Rather than ball milling your rocks, roast them in a bisque fire and =
then run them through a "Dolly Pot", an implement no self respecting =
prospecting geologist would be seen without.
Best regards,
Ivor Lewis. Redhill, South Australia
Catherine White on fri 27 jun 03
Please let us know your results from the granite and the volcanic ash.
Pictures would be even better if you have someplace to post them!
Catherine in Yuma, AZ
----- Original Message -----
>
> I will calcine the granite next time. The grus is the granite crumbles.
> The pieces we put in were all about a .25 inch or smaller. It made it
thru
> the hardware cloth. I have no idea why the kitty litter got tossed in.
It
> just seemed like a good idea to the "tame" geologists..
>
> Right now since we have something creamy and much of the grus and marbles
> are gone, I am tempted to strain it, add wood ash and whatever else is
> suggested and let 'er rip.
Janet Kaiser on fri 27 jun 03
The glass used for marbles is surely more like Pyrex these days? That could
be one reason that they are still whole and not already completely
pulverised.
But I am not certain why you have added glass marbles and clay to your
granite mix? Is that really a good idea? I only ask, because it seems to
me you are adding yet more variables that you will not be able to reproduce
in any resultant "wonder glaze" AND granite would surely not need any
addition of silica or clay?
I have recently been advised by various Clay buddies, that granite is easy
to grind or mill, BUT only after it has been calcined. It is going to take
you forever simply tumbling away, if it is anything like the granite we
have here in Wales!
I believe that no matter where the granite is from, it already has a high
silica content... around 75%? It also contains 10-15 % alumina and various
other constituents with up to 3% iron... So my best advice would be to
first calcine some granite "chips" and then grind/mill it before going on
to do some tests. If your tame geologists could get an analysis of the
local granite you are using, you would be at an even greater advantage and
be better able to work out a glaze in theory, before putting it into
practice.
Just using milled granite on its own (without those other clay and glass
marble additives) will also lead to more consistency in your tests.
I am sure rockers like Tony C. and Hank M. will be able to advise you
more... This is just my tuppence worth!
Janet Kaiser
**********************************************************************
TRUTH is too precious to tell every fool who asks for it...
****** This post was sent to you today by Janet Kaiser *******
The Chapel of Art / Capel Celfyddyd
8 Marine Crescent, Criccieth LL52 0EA, Wales, UK
Tel: ++44 (01766) 523570 URL: http://www.the-coa.org.uk
**********************************************************************
Zoe Paddy Johnson on sat 28 jun 03
I will order a copy as soon as I find one. My tame geologists are
paleontologists, so they wouldn't admit to knowing what a dolly pot is,
although I found out with some web research. My wood ash arrives this
weekend. We have been so drought stricken here in Albuquerque that I am
having to import the ash via a friend who lives where fires aren't
prohibitted. The grad student in geology kid thinks we should dump the ash
into the "ball mill" along with the creamy stuff we have and let it run
awhile, then we will fire some and post the result to one of the kiddo's
web pages. This whole project started as a fun project to keep my somewhat
elderly kids involved in family life. It has worked so far.
zoej
--On Friday, June 27, 2003 3:29 PM +0930 iandol wrote:
>
>
> Dear Zoe Paddy Johnson,
>
> May I suggest you look for a slim volume entitled "Rock Glazes" by Ivan
> Englund ISBN 0-9591764-0-3.
>
> Rather than ball milling your rocks, roast them in a bisque fire and then
> run them through a "Dolly Pot", an implement no self respecting
> prospecting geologist would be seen without.
>
> Best regards,
>
> Ivor Lewis. Redhill, South Australia
Ababi on sat 28 jun 03
I have the E book A Potter's Geology. of Eric Rowe
think it is a good book. I am not traveling enough to use all the benefits the author
offers but it is certainly a good source of knowledge in this direction
http://digitalfire.com/books/517.php
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.matrix2000.co.nz/Matrix%20Demo/Ababi.htm
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