Janet H Walker on wed 8 apr 98
I have seen a number of references on the list to the demise of
Calgon as a deflocculant for slips and terra sigs. I gather that it
used to be sodium hexametaphosphate (but I don't know if it said
that on the box.) Some have said "the new stuff just gives you muck".
In the course of trying to pass this info on to someone else, I
quickly ran into questions I couldn't handle. Like, when did it
change? But my old box will last forever, right? What about the
liquid stuff? Why wouldn't the new stuff work? What do you use
instead?
Elsewhere I've also seen enthusiasm about using Darvan instead of
soda ash/sodium silicate for deflocculating. Always happy to use
one ingredient instead of two. But I haven't found yet an
indication of what the "active ingredient" is for Darvan and how you
know how much to use.
In fact that was a real source of confusion to the people I was
talking to. How to know how much to use of any of these mystery
ingredients. The recipes they are depending on are all enshrined in
the oral tradition of the studio. But different recipes specify
different amounts of different magic ingredients, which people (self
included so far) have only the vaguest understanding of. And it is
easy to put in too much deflocculant, yes? (How do you know when
you have done so? what's the effect and how do you recover?)
So, this boils down to asking for info on the following:
- Whether or not Calgon works, is Darvan #7 a substitute for it?
- Does the Calgon currently sold work as a deflocculant?
- What is the recommended way of determining how much to use when
the recipe doesn't say or when you are substituting?
Thanks for info & references to Authoritative Sources
Jan Walker
Cambridge, MA USA
Stephen Mills on thu 9 apr 98
The Calgon available in the UK is no good for terra sig. As a result we
are selling Sodium Hexametaphosphate to our customers for that purpose.
No-one over here seems to have come up with a reliable substitute yet,
at least not that I've heard of.
Steve
Bath
UK
In message , Janet H Walker writes
>----------------------------Original message----------------------------
>I have seen a number of references on the list to the demise of
>Calgon as a deflocculant for slips and terra sigs. I gather that it
>used to be sodium hexametaphosphate (but I don't know if it said
>that on the box.) Some have said "the new stuff just gives you muck".
>
>In the course of trying to pass this info on to someone else, I
>quickly ran into questions I couldn't handle. Like, when did it
>change? But my old box will last forever, right? What about the
>liquid stuff? Why wouldn't the new stuff work? What do you use
>instead?
>
>Elsewhere I've also seen enthusiasm about using Darvan instead of
>soda ash/sodium silicate for deflocculating. Always happy to use
>one ingredient instead of two. But I haven't found yet an
>indication of what the "active ingredient" is for Darvan and how you
>know how much to use.
>
>In fact that was a real source of confusion to the people I was
>talking to. How to know how much to use of any of these mystery
>ingredients. The recipes they are depending on are all enshrined in
>the oral tradition of the studio. But different recipes specify
>different amounts of different magic ingredients, which people (self
>included so far) have only the vaguest understanding of. And it is
>easy to put in too much deflocculant, yes? (How do you know when
>you have done so? what's the effect and how do you recover?)
>
>So, this boils down to asking for info on the following:
> - Whether or not Calgon works, is Darvan #7 a substitute for it?
> - Does the Calgon currently sold work as a deflocculant?
> - What is the recommended way of determining how much to use when
>the recipe doesn't say or when you are substituting?
>
>Thanks for info & references to Authoritative Sources
>Jan Walker
>Cambridge, MA USA
>
--
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
paul wilmoth on sun 12 apr 98
Jan,
Do a direct substitution for your calgon with TSP (tri-sodium-phosphate).
This is a cleaner that you can find at any hardware store!
good luck - Paul
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