Overall's on thu 24 jul 08
A few weeks back, Ivor wrote something about
vinegar making clay thixotropic.
I don't understand what that means, but since
my last posting about me spraying vinegar and/or
vinegar water on pots to keep mold at bay, it
works great for that. It also works great in slip
as learned from Vince Pitelka.
However, when I spray vinegar water in/on moist clay
before wedging or using it, I don't like it at all.
It becomes "shorter", not easily manipulated
and feels stiff. As I'm using Balcones white
stoneware clay, I cannot say it reacts this way
with all clays.
In summary, vinegar is great in slip where a
wetter consistency is maintained or on predominately
finished work to counter mold development.
Not recommended to use before creating thrown or
most slab work.
Anyone else having different experiences, please
let us know.
Kim in Houston
Karin Givon on fri 25 jul 08
and I've been mending pots with vinegar and clay mixed together into
a slurry for about a hundred years.
I think I've used to it 'age' clay too but that may be a pipe dream.
A clay pipe , of course.
karin
On Jul 24, 2008, at 12:12 PM, Overall's wrote:
A few weeks back, Ivor wrote something about
vinegar making clay thixotropic.
I don't understand what that means, but since
my last posting about me spraying vinegar and/or
vinegar water on pots to keep mold at bay, it
works great for that. It also works great in slip
as learned from Vince Pitelka.
However, when I spray vinegar water in/on moist clay
before wedging or using it, I don't like it at all.
It becomes "shorter", not easily manipulated
and feels stiff. As I'm using Balcones white
stoneware clay, I cannot say it reacts this way
with all clays.
In summary, vinegar is great in slip where a
wetter consistency is maintained or on predominately
finished work to counter mold development.
Not recommended to use before creating thrown or
most slab work.
Anyone else having different experiences, please
let us know.
Kim in Houston
Ivor and Olive Lewis on fri 25 jul 08
Dear Kim in Houston,
You ask << A few weeks back, Ivor wrote something about vinegar making
clay thixotropic. I don't understand what that means,>>
Thixotropic substances appear to be solid, sometimes quite rigid. But
if they are subject to physical force they begin to soften, can become
flabby and even turn into a liquid.
I wrote, after saying that my reclaimed dry clay had changed character
from moderately acidic to slightly caustic "The basic Element will be
Potassium ions derived from Felspar. When first prepared the slurry
had a pH lower than 3. So the clay is now slightly caustic. I am
wondering if this will impart a degree of Thixotropy to the clay when
it is being worked "
I am still wondering. Remember, I was using Vinegar, one part to four
as a liquid in which to slake dry clay. I was not using raw vinegar.
By the way, I checked that clay out again today with the pH meter. It
gave a reading of pH7 and seems to be odourless. So it should be ready
to use.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ron Roy on thu 31 jul 08
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
>A few weeks back, Ivor wrote something about
>vinegar making clay thixotropic.
>
>I don't understand what that means, but since
>my last posting about me spraying vinegar and/or
>vinegar water on pots to keep mold at bay, it
>works great for that. It also works great in slip
>as learned from Vince Pitelka.
>
>However, when I spray vinegar water in/on moist clay
>before wedging or using it, I don't like it at all.
>
>It becomes "shorter", not easily manipulated
>and feels stiff. As I'm using Balcones white
>stoneware clay, I cannot say it reacts this way
>with all clays.
>
>In summary, vinegar is great in slip where a
>wetter consistency is maintained or on predominately
>finished work to counter mold development.
>
>Not recommended to use before creating thrown or
>most slab work.
>
>Anyone else having different experiences, please
>let us know.
>
>Kim in Houston
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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