Lori Wilkinson on sun 28 jul 96
Hi There,
Can anyone on the list tell me please the chemical name for the Calgon
softener used in making Terra Sigillata? I may be wrong but I think the
Calgon water softener NOW being sold in grocery stores is not of the same
chemical make up as what was sold a few years back. I am referring to what
WAS sold as calgon not what is being marketed at this time. TIA
Lori Wilkinson in Roswell New Mexico where the monsoons have made it clean
and green.
Karl P. Platt on sun 28 jul 96
>>Can anyone on the list tell me please the chemical name for the Calgon
softener used in making Terra Sigillata?<<
Sodium Hexametaphosphate.......
Accept no substitutes, except:
Tetrasodium pyrophosphate (TSPP) which, to my experience, is far more effective.
BobWicks@aol.com on sun 28 jul 96
Hi Lori:
I don't know the formula for the Calgon that you are using however I looked
up the ingredients lists of the currently marketed Calgon and it has 4 Sodium
compounds in it and to my best judgement, would add a considerable fluxing
action. Now I'll tell you why I think this. I have been teaching a Raku
class recently and have added Calgon to my Raku glaze as it makes it mix very
easily without lumps. The result was that the glaze flows all over
everything. Another use that I have put Calgon to is to mix my kiln wash
with it. Again it made the mix flow beautifully with no lumps and the wash
does not flake off. However on the other hand if I do indeed have a glaze
spill and have to use a chisel it off, I have a terrible time even getting
the kiln wash off, which tells me that there must have been a lot of fluxing
action taken place. This being the case the amount of Calgon used should be
measured and controlled.
As far as using this with Terra Siglatta, to me all indications would be that
it should work well. You might do better to use a teaspoon of anti freeze to
your TS mixture. I have used this very sucessfully. Another thing you might
like to try is to use a teaspoon of Liquitex Polymer Medium/ quart to your TS
mixture. This also works great! This makes the colloid act very
thixotropic, so it must be stirred vigously just prior to using. The result
is that the mixture covers evenly and with considerable ease. I think you
will like it.
Good luck to you.
Bob
Fred Paget on tue 30 jul 96
>Can anyone on the list tell me please the chemical name for the Calgon
>softener... I am referring to what
>WAS sold as calgon not what is being marketed at this time. ...
>
>Lori Wilkinson <
What you want is Sodium hexametaphosphate as has been elucidated several
times on CLAYART. Unfortunately it is not sold by Calgon anymore as far as
I can find out. It was used as a water softener but has a high phosphate
content which is bad for our rivers and lakes in commercial quantities. You
can still get the chemical from tie dye suppliers such as Dharma Trading
Company 1604 4th St.,(415)456-1211 in San Rafael, CA 94901. They also have
candle making supplies and little squeeze bottles with fine quality metal
nozzles like short blunt hypodermic needles..
Fred Paget---Mill Valley,CA,USA
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