Overall's on mon 4 aug 08
Ron,
Merely the words flocculation and deflocculation creates
a mental block.
Simplistically, if something flocculates,
does it mean to flock (attract) together in a grouping like
geese or the sprayed white clumpings on christmas trees?
and to defloc (repel) is to separate the mass?
akin to polarity of north and south poles?
I use the vinegar to counter the mold on pots when carving.
and in slip instead of water. On clay to be wedged, thrown
or handbuild it is awful to try and manipulate if any vinegar
is spritzed on or added.
Your description definitely helped.
Thanks!
Kim in Houston
5a. Re: vinegar and clay again...
Posted by: "Ron Roy" ronroy@CA.INTER.NET
Date: Wed Jul 30, 2008 10:58 pm ((PDT))
Hi Kim,
Vinegar does not deflocculate clay - it flocculates it - which is the
opposite of thixotropic.
When you add vinegar to clay it gets harder because flocculated clay
needs
more water to have a workable consistency - which probably explains why
you
are having trouble.
The drawback of using water to plasticize clay is the smell it
generates
after a few weeks - if your clay needs something to help the plasticity
(or
counter deflocculation) Epsom salts works well and keeps on working.
Just
make sure it's completely dissolved in water first and don't add too
much.
RR
Lesley Anton on mon 4 aug 08
Dear Ron Roy, or also Kim in Houston, or also, any slip casters out
there, too.....
I have been under the impression for some time, that vinegar is a good
thing to use on the seams of slip cast pieces to help them not show so
much when fired.
I am not having any luck with disguising the seams on some of my pots
- particularly, lamps...large lamps that are cone 10 fired, some
reduction, some oxidation - but most are showing seamlines no matter
how smooth I get them - and with so much advice over the last few
years. Argh. Because of the compression that happens when you are
trying to trim the seams, I was told that vinegar would "decompress"
the clay. Hah!! It ain't working!
The worst is shino - the carbon trapping is completely afraid of the
seams.
Now, after reading this last post from Ron, I gather that the vinegar
is actually making it worse by hardening that seam up, so that the
glaze doesn't absorb properly.
Ron said...."Vinegar does not deflocculate clay - it flocculates it -
which is the opposite of thixotropic. When you add vinegar to clay it
gets harder..."
I thought I noticed a positive difference when I started using it but
it's been so long that I might have be totally dillusional. Or ...I
got the advice from someone that I thought completely knew what they
were talking about.
This is the first post that I've read that addresses this very issue I
am having trouble with.
So- am i to understand that Epsom salts would actually do what I
need? Decompress the clay along the seamline, so that the glaze can
absorb properly, like on the rest of the pot? I would brush it on
during the leather hard stage?
oh - if this works I would be such a happy bunny!!
Thanks for any thoughts on this,
Lesley Anton
lesleyanton.com
Lesley Anton on thu 7 aug 08
Hi Mr. Lewis,
Thanks for the response.....
Wow, those 3 suggestions sound great, if it weren't for the fact that
I have 130 large lamps (27" tall) to treat at this particular time
(lesleyanton.com). Lightly hammering might be a way, I do sand
(ground?) the seams if there's still something showing after bisquing,
which there usually isn't, but cutting a groove and refilling
certainly isn't workable. - what about brushing on slip over the
seam? or a light slip wash over the whole pot. Might that help glazes
think they're going on over an even surface?
I've had a few responses suggesting that -
what do you think?
I'll try Jonathan Kaplan, too.
thanks so much,
Lesley Anton
<<<
Dear Lesley Anton,
Lawrence and West, "Ceramic Science for the Potter" attribute this
fault to particle orientation effects.
They draw on Norton for their information in suggesting that seams
should be
1, lightly hammered to induce plastic flow.
2, Bisque fired and then ground to remove the proud material.
3, Cut a groove in the leather hard clay and refill with plastic clay.
I think Jonathan Kaplan would have the best information if you can
contact him.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ron Roy on sat 9 aug 08
Hi Kim,
You have the right idea - sheep flock together usually - if you dive an
airplane at the flock it will deflock.
Flocculated clays will try to stay together - not crack when a coil is
wound around a finger or not break when a handle is pulled.
Flocculated glazes will stay suspended longer and need much less mixing
when you get ready to use them.
There is a good explanation in the Hamer dictionary by the way. Flocculated
particles are attracted to one another - deflocced particles repel one
another.
I don't know if it important for every potter to know this kind of
information - I do know that when trying to solve problems it becomes very
important.
RR
>Ron,
>
>Merely the words flocculation and deflocculation creates
>a mental block.
>
>Simplistically, if something flocculates,
>does it mean to flock (attract) together in a grouping like
>geese or the sprayed white clumpings on christmas trees?
>
>and to defloc (repel) is to separate the mass?
>akin to polarity of north and south poles?
>
>I use the vinegar to counter the mold on pots when carving.
>and in slip instead of water. On clay to be wedged, thrown
>or handbuild it is awful to try and manipulate if any vinegar
>is spritzed on or added.
>
>Your description definitely helped.
>Thanks!
>
>Kim in Houston
>
>5a. Re: vinegar and clay again...
> Posted by: "Ron Roy" ronroy@CA.INTER.NET
> Date: Wed Jul 30, 2008 10:58 pm ((PDT))
>
>Hi Kim,
>
>Vinegar does not deflocculate clay - it flocculates it - which is the
>opposite of thixotropic.
>
>When you add vinegar to clay it gets harder because flocculated clay
> needs
>more water to have a workable consistency - which probably explains why
> you
>are having trouble.
>
>The drawback of using water to plasticize clay is the smell it
> generates
>after a few weeks - if your clay needs something to help the plasticity
> (or
>counter deflocculation) Epsom salts works well and keeps on working.
> Just
>make sure it's completely dissolved in water first and don't add too
> much.
>
>RR
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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