PJLewing@aol.com on sun 19 may 96
This is a posting for a friend who does raku. She has a raku glaze that has
a lot of bone ash in it that fires to a sort of crinkly, puckered surface,
almost like it's starting to crawl but doesn't. Recently she got some new
bone ash, and the glaze came out like peeling paint, looking like the little
sharp-edged pieces were going to flake off. I gave her some of my bone ash,
she remixed the glaze, and it was fine.
The stuff she had had was light and fluffy, as was what I had. The new stuff
was dense and granular. The supplier says these are two different kinds of
bone ash, one is calcined cow bones, the other is synthetic. Also that one
of them (I don't know which) is Tricalcium phosphate, and the other dicalcium
phosphate.
I've heard of tricalcium phosphate that is mined (apatite) but I've never
heard of synthetic bone ash or tricalcium phosphate, and I've never heard of
dicalcium phosphate, nor do any of my books mention either. Is the clay
supplier just making this up? (Not unheard of in their case) Is one of these
things bone ash, and the other apatite, or is one of them something new?
She'd appreciate any input from the experts out there, and thanks you in
advance.
Paul Lewing, Seattle
Peet Robison on mon 20 may 96
Hi Paul;
Your supplier was right, there are two different types of bone ash. The light
and fluffy is tri-calcium phosphate and the dense granular is di-calcium
phosphate. It makes a tremendous difference which one you use.
I use di-calcium to make a phosphate opal glass, and when I tried tri-cal I had
MUCK. I think you could cut back on the alkali earth in your glaze and use the
tri-cal if you had too, but I like the 2CaPO3.
Peet, back to lurking in HOT Santa Fe
David Hewitt on mon 20 may 96
Hi Paul,
I am not too knowledgeable about Bone Ash but I do use it.
My understanding is that it is a very variable material and while the
generic formula is 3CaO.P2O5 (tricalcium phosphate) the proportions
could vary as much as being 13CaO.4P2O5. Dicalcium phosphate would
presumably be 2CaO.P2O5 but I have never met it.
I believe that all that I have used is from cows bones, but I read that
other sources are phosphorite and apatite and I assume these to be
mineral sources. I have checked with my supplier and he has not heard of
a synthetic bone ash.
I hope in some way that this helps your friend. Changes in material
compositions can be a real nuisance.
David Hewitt
Carolyn Sawyer on mon 17 may 99
Do I understand correctly that I can't purchase bone ash anymore because of
Mad Cow Disease? How comparable is the synthetic bone ash as far as the
outcome in the glaze?
Carolyn
the newbie with too many questions
Mo and Les Beardsley on tue 18 may 99
Carolyn Sawyer wrote:
>
> ----------------------------Original message----------------------------
> Do I understand correctly that I can't purchase bone ash anymore because of
> Mad Cow Disease? How comparable is the synthetic bone ash as far as the
> outcome in the glaze?
> Carolyn
> the newbie with too many questions
Carolyn
I use the synthetic bone ash and it works well. It is a bit lighter
in physical weight. I use gram for gram of regular bone ash.
Good Luck
Les Beardsley in Ladysmith on Vancouver Island where if the rain and
cold weather keeps up I'm going to be washed into the ocean.
Phil Rowley on wed 19 may 99
NONSENSE !
Bone ash is, of course, still available. It has, after all, been calcined at
well over 1000 degrees Celcius and is
therefore completely sterile.
Phil Rowley
----- Original Message -----
From: Carolyn Sawyer
To:
Sent: 17 May 1999 16:40
Subject: Bone Ash
> ----------------------------Original message----------------------------
> Do I understand correctly that I can't purchase bone ash anymore because
of
> Mad Cow Disease? How comparable is the synthetic bone ash as far as the
> outcome in the glaze?
> Carolyn
> the newbie with too many questions
>
Ted Eisenstein on thu 20 may 99
>>Bone ash is, of course, still available. It has, after all, been calcined at
well over 1000 degrees Celcius and is
therefore completely sterile.
<<
For that matter. . . (and here I take a big stretch into uncharted
areas) is there any reason why someone couldn't make bone ash
at home, by collecting enough bones and burning them in a kiln?
I am told it's quite smelly, but doable, at least theoretically.
Can it be done? Has anyone tried this?
Ted Eisenstein, in the wilds of the middle of Missouri
Carolyn Sawyer on thu 20 may 99
Well, I was informed by the employees at Highwater Clay in Asheville NC that
bone ash is no longer available because the ash came from cow bones from
England or maybe Europe in general. They told me that synthetic was the only
form available. That was the only form that they carried. Many of you e
mailed me privately to tell me that the forms are similar if not identical.
Carolyn
CNW on sat 22 may 99
While it's true that bone ash is still available it's not necessarily
because of processing. I recall having seen a documentary on 'mad cow' and
it's sheep equivalent 'scrapie' that they have found no way to effectively
destroy the disease because it is not carried/transmitted in a typical
manner. They found it still virulent after being buried, incinerated, etc. I
can't remember what show but I believe it was on a PBS station.
But the big thing is that there has been no evidence of 'mad cow' in the
U.S. Plus there has not been a huge outbreak of mad humans in Europe. Or
rather no larger than anywhere else ;^)
And finally wear your mask !!!! It doesn't matter what the disease is
caused by; proteins, silica, asbestos, cotton fiber, etc. you don't need to
be breathing in a lot of extraneous junk anyway.
Celia in NC eating beef and trying to avoid snorting fine powders of any
sort (snort?)
Stephen Mills on sat 22 may 99
Anything that needs calcining can be calcined in a kiln. The bugger is
grinding it down afterwards.
Steve
Bath
UK
In message , Ted Eisenstein writes
>----------------------------Original message----------------------------
>>>Bone ash is, of course, still available. It has, after all, been calcined at
>well over 1000 degrees Celcius and is
>therefore completely sterile.
><<
>
>For that matter. . . (and here I take a big stretch into uncharted
>areas) is there any reason why someone couldn't make bone ash
>at home, by collecting enough bones and burning them in a kiln?
>I am told it's quite smelly, but doable, at least theoretically.
>
>Can it be done? Has anyone tried this?
>
>Ted Eisenstein, in the wilds of the middle of Missouri
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
ababy sharon on wed 16 feb 00
A question!
What is the influence of the Bone Ash , on raku glazes?Color, flux, how much
can I put in the
recipe?
Thanks
Ababi.
Chris Cantello on thu 17 feb 00
+++++++++++++++++++++++++
+++ Raku Gold ^06 +++
+++++++++++++++++++++++++
This Glaze works best for me hope it will for you as well.
Firing type: Raku
Glaze type: Raku (Copper matt)
Color: copper flash
Surface: Matt
Transparency: Opaque
Crystals: None
Bubbles: None
Flow: None
Flaws: Crawls\when thick
Durability: Good
Testing: good one
Date: 02/16/00
Gerstley borate 62.64 62.6%
Nepheline syenite 13.19 13.2%
Bone ash 20.88 20.9% Hazard!
Frit 3124 3.3 3.3%
-------- ------
100 100 %
Copper carbonate 6.59 6.6% Hazard!
Cobalt carbonate 1.65 1.6% Hazard!
Manganese dioxide 2.2 2.2% Hazard!
Notes:
You must flash the pot quickly with in 10 to 15 sec. after its been
in the can. Then leave be to cool slow for 25 min.
Material Hazards:
Bone ash - skin irritant
Copper carbonate - poisonous - fumes can be toxic above c/8
Cobalt carbonate - irritant
Manganese dioxide - poisonous
Cost: $ 2.92 per kg glaze
$ 0.29 per 100 g batch
===========================
Chemical Analysis
===========================
This glaze contains unexpected oxides: SiO2
Na2O 0.04 Al2O3 0.05 P2O5 0.10
K2O 0.01 B2O3 0.72
CaO 0.81
MnO 0.04
CoO 0.02
CuO 0.08
Alumina:Silica ratio is 1.00 : 4.68
Neutral:Acid ratio is 1.00 : 0.12
Alkali:Neutral:Acid ratio is 1.00 : 0.78 : 0.10
Na2O 1.6% Al2O3 3.8% P2O5 9.5%
K2O 0.8% B2O3 34.8%
CaO 31.2%
MnO 1.9%
CoO 1.1%
CuO 4.6%
This glaze also contains:
SiO2 10.6%
Loss On Ignition: 16.1%
Expansion coefficient: 84.8 x 10e-7 per degree C
Oxides causing abnormal expansion effects: B2O3
Surface Tension index: 2.5
Materials in glaze:
Gerstley borate provides B2O3 and CaO.
Nepheline syenite provides SiO2, Al2O3, Na2O, and K2O
Bone ash provides CaO and P2O5. Usually used as an opacifier.
Frit 3124 supplies SiO2, Al2O3, CaO, B2O3, Na2O, and a trace of K2O..
Copper carbonate provides CuO. Used as a colorant.
Cobalt carbonate provides CoO. Used as a colorant, acts as flux.
Manganese dioxide provides MnO. Used as colorant.
Oxides in glaze:
Na2O is a strong alkaline flux.
K2O is a strong alkaline flux.
CaO is a high-temperature flux.
MnO is a colorant (black, brown, and purple).
CoO is a colorant (blues and purples).
CuO is a colorant (greens, blue-greens, reds, and copper lusters).
Al2O3 increases viscosity, prevents crystallization, and adds durability.
B2O3 is both a glass-former and a flux over a wide temperature range.
P2O5 is a glass-forming oxide and opacifier.
SiO2 is the primary glass-former in glazes.
=======================
Cost Summary
=======================
Gerstley borate 62.6% $ 0.65 per kg glaze
Nepheline syenite 13.2% $ 0.06
Bone ash 20.9% $ 0.60
Frit 3124 3.3% $ 0.10
------ -------
100 % $ 1.40 per kg glaze
Copper carbonate 6.6% $ 0.65 per kg glaze
Cobalt carbonate 1.6% $ 0.80
Manganese dioxide 2.2% $ 0.06
-------
$ 1.51 per kg glaze
Total cost: $ 2.92 per kg glaze
$ 0.29 per 100 g batch
Jon Pacini on fri 2 mar 01
Greetings All------Eastman synthetic Bone Ash has the following =
analysis;
Calcium phosphate dihydrate---CaHPO4--2 H2O
Phosphorus---18.5% minimum
Calcium--------22.5% min.
Florine-------------.07% maximum
Acid insoluables--.35%
moisture----------3%
LOI---------------18% max.
A little loose on their %s but thats the Official Data sheet.
Jon Pacini
Clay Manager
Laguna Clay Co
jpacini@lagunaclay.com=20
Craig Martell on sun 28 apr 02
Hello John:
The info I sent about dicalcium phosphate came out of the Matrix V Raw
Materials database. I'm thinking that this may represent a calcined
material.
There may be some loss of oxides from Apatite during processing too. I'm
not sure about this stuff and it's a bit difficult to get info
sometimes. I'm in a glazing-firing crunch at present so I'll have to give
this some proper investigation when I'm through with the Oregon Potter's
show next weekend.
regards, Craig Martell in Oregon
Tom's E-mail on sun 28 apr 02
I attempting to make up a synthetic pine ash using an analysis found in =
Grebanier's book Chinese Stoneware Glazes. I've used the Seger method =
but am stuck on one of the ingredients namely P2O5. I have two sources =
of phosphorous at hand namely bone ash in the di and tri forms. My =
question is which should I use and how do they break down, i.e. how many =
moles of Calcium and P2O5. I'm thinking that I want the consistency of =
dealing with a known quality rather than variations from batch to batch =
of collected ash. Thanks for any help.
Tom Sawyer
tsawyer@cfl.rr.com
John Hesselberth on sun 28 apr 02
on 4/28/02 11:42 AM, Tom's E-mail at tsawyer@CFL.RR.COM wrote:
> I attempting to make up a synthetic pine ash using an analysis found in
> Grebanier's book Chinese Stoneware Glazes. I've used the Seger method but
am
> stuck on one of the ingredients namely P2O5. I have two sources of
phosphorous
> at hand namely bone ash in the di and tri forms. My question is which
should I
> use and how do they break down, i.e. how many moles of Calcium and P2O5.
I'm
> thinking that I want the consistency of dealing with a known quality
rather
> than variations from batch to batch of collected ash. Thanks for any help.
>
> Tom Sawyer
>
> tsawyer@cfl.rr.com
Hi Tom,
Great question! This sent me to several books and 3 or 4 catalogs. I hope I
got it right.
Calcium and phosphorus combine with each other in all sorts of strange ways.
I think there are seven listed in my Handbook of Chemistry and Physics. The
one that is typically called bone ash (I think most of the bone ash we get
is synthetic these days) is tricalcium phosphate. However some pottery
suppliers appear to carry dicalcium phosphate and call it bone ash without
telling you what it is in their catalog. What I found surprising is that
dicalcium phosphate was being offered as bone ash--I wasn't aware of that.
The only way to know for sure what your supplier is carrying is to ask for
an analysis or an MSDS.
Your primary supplier (Axner) lists in his catalog that his is tricalcium
phosphate. That is the one I would prefer simply because the dicalcium
material exists as a hydrate whereas the tricalcium does not. That means
less LOI (less off-gassing during firing) for the tricalcium phosphate.
Tricalcium phosphate also seems to be more expensive, but then it isn't
carrying all that water around.
In either case, of course, make sure the appropriate analysis and LOI are
entered in your glaze calc program.
Regards,
John
Web sites: http://www.masteringglazes.com and http://www.frogpondpottery.com
Email: john@frogpondpottery.com
"The life so short, the craft so long to learn." Chaucer's translation of
Hippocrates, 5th cent. B.C.
Craig Martell on sun 28 apr 02
Tom sez:
>I have two sources of phosphorous at hand namely bone ash in the di and
>tri forms. My question is which should I use and how do they break down,
>i.e. how many moles of Calcium and P2O5.
Hello Tom:
If you have dicalcium phosphate and tricalcium phosphate the source for
this stuff might be the mineral Apatite. Apatite is not really bone ash
which is just fine. If you want to eliminate variability in your glaze the
mineral source of calcium phosphate is going to be more consistent. From
reading I've done about Bone Ash and mineral sources of Calcium Phosphate
there seems to be a bias toward animal Bone Ash for depth and richness of
effect. I would probably try both sources and see what's preferable to
you. It doesn't matter what anyone else thinks, it's your work.
The seger analysis of dicalcium phosphate is:
Ca 1.0, P2O5 0.499 molecular wt. 126.923 LOI is zero.
regards, Craig Martell in Oregon
John Hesselberth on sun 28 apr 02
Hi Craig,
Now I'm confused. Help me please. My handbook says Apatite is
CaF2.3Ca3P2O8. That would certainly have F in unity or an LOI depending on
how you treat the fluorine. I didn't calculate the molecular weight, but it
would be way over 126--it has 400 just of calcium. My handbook also says
dicalcium phosphate is CaHPO4.2H2O with a molecular weight of 172.1
Where am I getting confused??
John
on 4/28/02 1:48 PM, Craig Martell at ashglaze@WVI.COM wrote:
> If you have dicalcium phosphate and tricalcium phosphate the source for
> this stuff might be the mineral Apatite.
>
> The seger analysis of dicalcium phosphate is:
> Ca 1.0, P2O5 0.499 molecular wt. 126.923 LOI is zero.
Web sites: http://www.masteringglazes.com and http://www.frogpondpottery.com
Email: john@frogpondpottery.com
"Art is not a handicraft, it is the transmission of feeling the artist has
experienced." Leo Tolstoy, 1898
June on fri 14 aug 09
Hank,
Could you please post that 32% bone ash recipe on the list. I'd love to try=
it.
Warm Regards,
June
http://www.shambhalapottery.blogspot.com
http://www.shambhalapottery.com
http://groups.yahoo.com/group/sodasaltfiring/
http://saltandsodafiring.ning.com/
http://ncclayclub.blogspot.com
________________________________
From: Hank Murrow
To: Clayart@LSV.CERAMICS.ORG
Sent: Wednesday, August 12, 2009 11:57:55 PM
Subject: Re: bone ash
On Aug 12, 2009, at 7:47 PM, David Hendley wrote:
> Hi Hank, this is interesting. I didn't know you used so much bone ash.
> My question is, do you use "tri-calcium phosphate" these days, and
> just substitute it 1-for-1 in a recipe from the days of yore that
> calls
> for bone ash ?
Dear David;
I have a 400# supply of Kodak 'real bone ash'. They are getting out
of film, so I don't know how long they'll be using bone ash. It makes
a difference in my glazes, and I do use a lot of the stuff....... one
of my faves. I can send you a recipe to try that 32% one.
Cheers, Hank
Cone 10 Reduction in a hardbrick gas kiln. Ru/Fe brushed on top and
Co2Fe for the blue. Fe for the brown.
Hank Murrow on fri 14 aug 09
On Aug 14, 2009, at 5:18 AM, June wrote:
> Hank,
>
> Could you please post that 32% bone ash recipe on the list. I'd
> love to try it.
OK. It is published in Ian Curries "Revealing Glazes", and now here:
Glaze name: Cory's Weird
Cone: 9 - 10
Color: oatmeal to white
Surface texture: smooth and fatty
Firing: Reduction
Recipe: Percent Batch
Nepheline Syenite 32.00
Whiting 3.00
Real Bone Ash 32.00
Talc 13.00
Kaolin 18.00
Silica 2.00
Totals: 100.00 %
Comments:
Developed by Cory Levins @ Alfred in '71 after a glaze lecture by
Daniel Rhodes, who declared "You can't have more than 5% bone ash in
a cone 10 glaze." Cory always tested theory, so he made tests with
varying amounts of bone ash from 5 to 50%. Of course, he had several
nice ones in the results, and this one became my favorite and I named
it Cory's Weird. This is pretty close to the recipe as I used it in
Aspen. Brush with Fe/Ru for iron red to orange, Fe for rich brown,
2Fe/Co for blue-black, Ferric Phosphate for iron red, Thinnish Co for
soft blue.
Unity Formula for Cory's Weird Original:
0.032 K2O 0.271 Al2O3 1.229 SiO2
0.098 Na2O 0.001 Fe2O3 0.002 TiO2
0.667 CaO 0.200 P2O5 4.5:1 Si:Al =
Ratio
0.203 MgO
Percentage Analysis for Cory's Weird Original:
39.95 % SiO2
14.95 % Al2O3
1.63 % K2O
3.29 % Na2O
20.25 % CaO
4.43 % MgO
0.09 % Fe2O3
15.33 % P2O5
0.09 % TiO2
Note the low Silica and high Phosphorus content. Phosphorus is a
glass former.
Cheers, Hank in Eugene
www.murrow.biz/hank
Bonnie Hellman on fri 14 aug 09
I believe you can make your own natural bone ash.
Lori Leary was the one who first told me that you can make your own bone
ash, reasonably easily, by putting animal bones in a bisque firing. This
softens them so they can pretty easily be ground up. I watched her do this
at a Brian Gartside workshop.
We get cow femurs (cut up by our local butcher) for our dog, and when the
dog has finished chewing on them, if there is anything left, I save them to
fire in my next bisque firing.
Perhaps Lori or someone else who has done it will comment on this.
Bonnie
Bonnie D. Hellman
Ouray, Colorado 81427
----- Original Message -----
From: "peter h. pache"
To:
Sent: Thursday, August 13, 2009 11:30 AM
Subject: Re: bone ash
David Hendley wrote:
>> My question is, do you use "tri-calcium phosphate" these days, and
>> just substitute it 1-for-1 in a recipe from the days of yore that
>> calls for bone ash?
Hank Morrow then wrote:
> I have a 400# supply of Kodak 'real bone ash'. They are getting out
> of film, so I don't know how long they'll be using bone ash.
I use 'real' bone ash from Ebonex:
http://ebonex.com/b_ash.htm
They were real nice to me and sent a 50 pound bag.
Peter
NM
June on sun 16 aug 09
Brian,
you can't just hit reply. If you hit reply, it goes to the person who wrote=
the message. For it to reach the Clayart list, you have to send it to the =
list using this address:
Clayart@LSV.CERAMICS.ORG
Also, you may not have seen your email because in your Clayart settings, yo=
u may have no opted to receive your own messages.
Love the tests, particularly the top 3 tests on the far right. That red/bur=
gundy one is spectacular, as is the aquamarine crystalline one.
Can you give us more information on the tests - cone, atmosphere, base glaz=
e, etc.
Regards,
June
http://www.shambhalapottery.blogspot.com
http://www.shambhalapottery.com
http://groups.yahoo.com/group/sodasaltfiring/
http://saltandsodafiring.ning.com/
http://ncclayclub.blogspot.com
________________________________
From: Brian
To: Clayart@LSV.CERAMICS.ORG
Sent: Saturday, August 15, 2009 5:49:12 PM
Subject: Re: bone ash
'think I haven't got used to the reply/reply all trick..........
my attempted posting didn't appear yesterday
here goes again
regarding bone ash
I have been working on updating my web site and also a new dvd/cd
about creating extreme (some say obnoxious) textures with glaze
materials. Here is a gallery of images I have just completed that show
bone ash (real) in action
30 - 50% of bone ash gets really active (stains were added)
http://gallery.me.com/beeeg#100458
Brian
----------------------------
Brian Gartside
Pukekohe,2677, New Zealand
http://www.gartside.info
http://www.briangartside.com
Paul Borian on tue 18 aug 09
Ivor,
thanks for providing this info - that basically answered my original
question.
the results of the first tests i have done (removing the bone ash from the
glaze) made the glaze
more fluid.
thanks,
Paul
On Aug 16, 2009 10:23pm, ivor & olive lewis wrote:
> Reading outside the square. Bone Ash is a notable refractory material in
> spite of being stuffed with three units of Calcium oxide which is regarde=
d
> generally as a fluxing agent. It is one of the main ingredients in the
> manufacture of crucibles used to refine precious metals including Platinu=
m
> with a melting point of over 1700 deg C. See "Cupellation"
> Ivor Lewis,
> Redhill,
> South Australia
Peter on fri 23 mar 12
Bill Merrill wrote:
<post it on Clayart.>>
In the past I've purchased bone ash (50 pound bag) from:
http://ebonex.com/b_ash.htm
& have found them to be very nice & helpful.
Peter
NM
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