Rick Hamelin on mon 2 jun 03
I am having a difficult time finding mol range limits or percentage limits for
Strontium Carb for 06-04. I have read of its fluxing ability in the -04 range
as a lead substitute (Parmelee), but only can find references and research for
midrange and higher ceramics. The threshold of when it begins to saturate the
glaze and lose its ability to be a clear, low temp flux is important to me.
Thanks
Rick
Paul Lewing on mon 2 jun 03
on 6/2/03 9:59 AM, Rick Hamelin at piedpotterhamelin@ATTBI.COM wrote:
> I am having a difficult time finding mol range limits or percentage limits for
> Strontium Carb for 06-04.
Rick, the only place I've ever seen SrO mentioned at all in a set of limit
formulas is in Zakin's "Mastering the Craft, and there it's only given for
cone 3-7 and cone 8-10. He says the limits for cone 3-7 are 0-.4, and for
cone 8-10 are 0-.7.
Maybe a little help, but not much.
Paul Lewing, Seattle
Lily Krakowski on mon 2 jun 03
Never having worked as low as that, I cannot do more than make a general
remark.
Strontium--albeit mentionned by Parmelee--was rarely used till recently
because of its cost. It was generally treated as a costly substitute for
calcium. Robin Hopper pointed out how much it had in common with barium,
something I tried with Barium blues and reported to the Letters column of CM
again, years ago....
So. I would suggest you find old barium recipes and replace the b with the
s.
Rick Hamelin writes:
> I am having a difficult time finding mol range limits or percentage limits for
> Strontium Carb for 06-04. I have read of its fluxing ability in the -04 range
> as a lead substitute (Parmelee), but only can find references and research for
> midrange and higher ceramics. The threshold of when it begins to saturate the
> glaze and lose its ability to be a clear, low temp flux is important to me.
> Thanks
> Rick
>
> ______________________________________________________________________________
> 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/
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> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
Ron Roy on tue 3 jun 03
Strontium Carb does not decompose at a low enough temperature (1075C) to be
used as a flux for low fired ware - see Hamer.
It will work at all temps if included in a frit however.
RR
>I am having a difficult time finding mol range limits or percentage limits for
>Strontium Carb for 06-04. I have read of its fluxing ability in the -04 range
>as a lead substitute (Parmelee), but only can find references and research for
>midrange and higher ceramics. The threshold of when it begins to saturate the
>glaze and lose its ability to be a clear, low temp flux is important to me.
>Thanks
>Rick
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
iandol on tue 3 jun 03
Dear Rick Hamelin,
I suspect we are not being told these things because they are not known. =
I would regard Strontium Carbonate as an impossible ingredient for Low =
Temperature Glazes. Do people say it will behave like Whiting and =
discharge its Carbon Dioxide during heating? This is not supported by =
the reference books. CRC give a melting point of 1494 deg C while Kaye =
and Laby say decomposition at 1340 deg C. Therefore you have to rely on =
the solvent properties of your Frits to get the stuff into solution and =
a speculative chemical reaction to discharge the CO2 at Cone 06-04.
I doubt the truthfulness of Strontium Carbonate to act as a replacement =
for Lead Oxide. Who said that or where does the idea originate and what =
is the evidence on which this claim is made?
I suggest if it is essential to use Strontia that you look through the =
Frit Lists.
Best regards,
Ivor Lewis.
J T on tue 3 jun 03
On 6/2/03 1:59 PM, "Rick Hamelin" wrote:
> I am having a difficult time finding mol range limits or percentage limit=
s for
> Strontium Carb for 06-04. I have read of its fluxing ability in the -04 r=
ange
> as a lead substitute (Parmelee), but only can find references and researc=
h for
> midrange and higher ceramics. The threshold of when it begins to saturate=
the
> glaze and lose its ability to be a clear, low temp flux is important to m=
e.
> Thanks
> Rick
>=20
> _________________________________________________________________________=
_____
> Send postings to clayart@lsv.ceramics.org
>=20
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>=20
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
I use the following Limits for Strontium
=9003 0 - .3
=906 0 - 0.5 =20
=9010 0 - .8
Regards,
John Richmond
Port Orange, Florida 32129
johnrichmond@mac.com
Rick Hamelin on wed 4 jun 03
I appreciate your answering my inquiry.
Hamer on page 286 of "The Potter's Dictionary" stated its use "since the late
19th century when it was tried as a substitute for lead oxide. The glaze
experiments were successful and lead-free and zinc-free non-poisonous glazes
were produced." "However, as a replacement for lead oxide on a molecular basis
(comparing cost, rh) strontia is worth consideration for glazes containing
small amounts of lead oxide". Hence, the suggestion is found here. The author
makes no attempt at defining the temperature range considered for testing this
material.
Parmalee, pages 20-21 of Ceramic Glazes discussed Clark's research of
strontium. Clark (and Parmalee) reviewed its increasing fluidity and
softening temperature in substituting for calcia or zinc. "When replacing lead
oxide in dinnerware on a molecular basis, strontia decreases fluidity,
increases the softening temperature and slightly increases thermal expansion."
"Clark concluded, as a result of the study, that superior glazes could be had
by using strontia for replacing some of the other bases, that satisfactory
leadless glazes may be had....than with high calcia containing compositions.."
"Harman and Swift studied the effect of strontia in raw glazes free from lead
and boric oxide and fired through a wide range of temperatures. The
compositions were characterized by exceptionally long firing ranges."
Perhaps it is true (I assume) that these experiments maybe were done in in the
Cone 1 or higher range, but this is not defined by either author. That is the
risk I find with published information; general undefined conclusions to be
taken as fact over our wide firing ranges.
I suspected that I could induce an earlier melt with the carbonate than its
1994'f fluxing start quoted by Hamer. I glaze fire at 05 and am currently
experimenting with a boron/ alkaline frit 58.3 -lith carb 1.2 -flint 12.8-
kaolin 12.0 -strontium 15.7 mixture that first was cloudy and stiff at 5-10-15
percent additions, but became clear and fluid, running off the pot at 20
percent (final 15.7 %). The tests were done in a smaller kiln, faster up and
down temps. After increasing the silica, crazing was practically eliminated
and the glaze was stiff, in this kiln.
When fired in my large electrics with longer heating and cooling periods, I
found the glaze more difficult to work with. Although having a wonderful
gloss, it did randomly develop towards a broken matted or crystallized
surface. Sometimes a green streaking is apparent. I am using 6% iron and
specifically wanted a clear glaze.
Perhaps the strontium frits should remedy this problem, but are not sold by my
suppliers. I will get some in the future.
Thanks for your thoughts,
Rick
> Dear Rick Hamelin,
>
> I suspect we are not being told these things because they are not known. I would
> regard Strontium Carbonate as an impossible ingredient for Low Temperature
> Glazes. Do people say it will behave like Whiting and discharge its Carbon
> Dioxide during heating? This is not supported by the reference books. CRC give a
> melting point of 1494 deg C while Kaye and Laby say decomposition at 1340 deg C.
> Therefore you have to rely on the solvent properties of your Frits to get the
> stuff into solution and a speculative chemical reaction to discharge the CO2 at
> Cone 06-04.
>
> I doubt the truthfulness of Strontium Carbonate to act as a replacement for Lead
> Oxide. Who said that or where does the idea originate and what is the evidence
> on which this claim is made?
>
> I suggest if it is essential to use Strontia that you look through the Frit
> Lists.
>
> Best regards,
> Ivor Lewis.
>
> ______________________________________________________________________________
> 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.
I
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