Tom Wirt on tue 12 oct 99
I know this subject was discussed some time ago....but it's reared it's ugly
head again and a search of the various archives didn't help.
We just got a bag of Strontium Carbonate and it was the kind of crystalline
version. This acts differently in the glaze we use it in.....giving a much
darker and browner coloring. Seems l;ast time we went through this, the
milled/powdered strontium later showed up in a 100 or so lb. barrel. Anyone
got any ideas on the chemistry of this change....or why it might make a
difference.
It doesn't all go through the screen, so it may be changing the percentage
in the recipe.
Help.
Any sources for the powdered stuff?
Tom Wirt
Clay Coyote Pottery
17614 240th St.
Hutchinson, MN 55350
320-587-2599 fax 320-234-6849
claypot@hutchtel.net
Dannon Rhudy on wed 13 oct 99
Tom, we only use strontium in quantity in a couple of glazes, and I
noted when making the last batches that there was a difference in
the appearance of the new bag of strontium - granular, in fact.
However, the glaze is behaving
precisely as before, to my pleased surprise. What glaze are you using,
percent strontium, cone? - Dannon
At 02:54 PM 10/12/99 EDT, you wrote:
>----------------------------Original message----------------------------
>I know this subject was discussed some time ago....but it's reared it's ugly
>head again and a search of the various archives didn't help.
>
>We just got a bag of Strontium Carbonate and it was the kind of crystalline
>version. This acts differently in the glaze we use it in.....giving a much
>darker and browner coloring. Seems l;ast time we went through this, the
>milled/powdered strontium later showed up in a 100 or so lb. barrel. Anyone
>got any ideas on the chemistry of this change....or why it might make a
>difference.
>
>It doesn't all go through the screen, so it may be changing the percentage
>in the recipe.
>
>Help.
>
>Any sources for the powdered stuff?
>
>Tom Wirt
>Clay Coyote Pottery
>17614 240th St.
>Hutchinson, MN 55350
>320-587-2599 fax 320-234-6849
>claypot@hutchtel.net
>
Ron Roy on thu 14 oct 99
Hi Tom,
I have noticed that my Strontium is granular - but goes through an 80M when
wet - takes a little longer than usual. It is probably granulated to cut
down on dust - you may find it better to use hot water to make it break
down faster or leave it in water with the other materials overnight.
If it is really crystalline then melting it with hot water before you put
it in the glaze might work.
There is usually some small amount of Barium Carb in Strontium Carb - my
book says 1 to 2.5%. There are 4 grades - light, low sulphur, granular
-pressed, and heavy calcined.
Note - Strontium Carb disassociates at 1100C - no use trying to use it as a
flux before that unless it's fritted.
RR
>----------------------------Original message----------------------------
>I know this subject was discussed some time ago....but it's reared it's ugly
>head again and a search of the various archives didn't help.
>
>We just got a bag of Strontium Carbonate and it was the kind of crystalline
>version. This acts differently in the glaze we use it in.....giving a much
>darker and browner coloring. Seems l;ast time we went through this, the
>milled/powdered strontium later showed up in a 100 or so lb. barrel. Anyone
>got any ideas on the chemistry of this change....or why it might make a
>difference.
>
>It doesn't all go through the screen, so it may be changing the percentage
>in the recipe.
>
>Help.
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Barney Adams on fri 15 oct 99
Ron
This confuses me. I thought SrO is a good flux between the wide range
of 800C through 2300C. Or is the disassociation apply to the carb form?
Barney
Ron Roy wrote:
> ----------------------------Original message----------------------------
> Hi Tom,
>
> I have noticed that my Strontium is granular - but goes through an 80M when
> wet - takes a little longer than usual. It is probably granulated to cut
> down on dust - you may find it better to use hot water to make it break
> down faster or leave it in water with the other materials overnight.
>
> If it is really crystalline then melting it with hot water before you put
> it in the glaze might work.
>
> There is usually some small amount of Barium Carb in Strontium Carb - my
> book says 1 to 2.5%. There are 4 grades - light, low sulphur, granular
> -pressed, and heavy calcined.
>
> Note - Strontium Carb disassociates at 1100C - no use trying to use it as a
> flux before that unless it's fritted.
>
> RR
>
> >----------------------------Original message----------------------------
> >I know this subject was discussed some time ago....but it's reared it's ugly
> >head again and a search of the various archives didn't help.
> >
> >We just got a bag of Strontium Carbonate and it was the kind of crystalline
> >version. This acts differently in the glaze we use it in.....giving a much
> >darker and browner coloring. Seems l;ast time we went through this, the
> >milled/powdered strontium later showed up in a 100 or so lb. barrel. Anyone
> >got any ideas on the chemistry of this change....or why it might make a
> >difference.
> >
> >It doesn't all go through the screen, so it may be changing the percentage
> >in the recipe.
> >
> >Help.
>
> Ron Roy
> 93 Pegasus Trail
> Scarborough
> Ontario, Canada
> M1G 3N8
> Evenings 416-439-2621
> Fax 416-438-7849
Ron Roy on sun 17 oct 99
Hi Barney,
Yes I should have said the carbonate - when I said disassociates at 1100C I
mean it goes from SrCO3 into CO2 and SrO. If incorporated into a frit Hamer
says it will start helping the melt at 650C - but it must be in association
with other fluxes of course.
Hamer says it is more like CaO in it's effect on colour and more like ZnO
in it's fluxing power. Too much will give matte surfaces.
It is not a good substitute for BaO if you are after that bright turquoise
colour - or the acid blue either - but I like it better for iron colours.
Just keep in mind that adding a little of any flux to a glaze will give
better melt and that gives us a chance to add more alumina and silica for
better durability.
SrO contributes to better gloss and durability so adding say 2% of the
carbonate to any higher fired glaze (above 1100C) glaze will probably make
it a more durable glaze - especially if you add more silica and alumina.
I recommend you get the Hamer book Barney - RR
>----------------------------Original message----------------------------
>Ron
>This confuses me. I thought SrO is a good flux between the wide range
>of 800C through 2300C. Or is the disassociation apply to the carb form?
>
>Barney
>
>Ron Roy wrote:
>
>> ----------------------------Original message----------------------------
>> Hi Tom,
>>
>> I have noticed that my Strontium is granular - but goes through an 80M when
>> wet - takes a little longer than usual. It is probably granulated to cut
>> down on dust - you may find it better to use hot water to make it break
>> down faster or leave it in water with the other materials overnight.
>>
>> If it is really crystalline then melting it with hot water before you put
>> it in the glaze might work.
>>
>> There is usually some small amount of Barium Carb in Strontium Carb - my
>> book says 1 to 2.5%. There are 4 grades - light, low sulphur, granular
>> -pressed, and heavy calcined.
>>
>> Note - Strontium Carb disassociates at 1100C - no use trying to use it as a
>> flux before that unless it's fritted.
>>
>> RR
>>
>> >----------------------------Original message----------------------------
>> >I know this subject was discussed some time ago....but it's reared it's ugly
>> >head again and a search of the various archives didn't help.
>> >
>> >We just got a bag of Strontium Carbonate and it was the kind of crystalline
>> >version. This acts differently in the glaze we use it in.....giving a much
>> >darker and browner coloring. Seems l;ast time we went through this, the
>> >milled/powdered strontium later showed up in a 100 or so lb. barrel. Anyone
>> >got any ideas on the chemistry of this change....or why it might make a
>> >difference.
>> >
>> >It doesn't all go through the screen, so it may be changing the percentage
>> >in the recipe.
>> >
>> >Help.
>>
>> Ron Roy
>> 93 Pegasus Trail
>> Scarborough
>> Ontario, Canada
>> M1G 3N8
>> Evenings 416-439-2621
>> Fax 416-438-7849
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
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