jonathan kaplan on sat 5 nov 11
There are a few types of Darvan products available from RT Vanderbilt.
My experience is that their Darvan 811 is a far superior product for =3D
deflocculation than Darvan 7. Their chemistry is different in that one =3D
is a long chained polymer and the other a short chained polymer. The are =
=3D
both sodium polyacrylates.
I have used the 811 product in terra cotta casting slips as well as both =
=3D
porcelains and whitewares. and purchase directly from RT Vanderbilt in =3D
approximately 5 gallon plastic pails. They do not ship in cold weather =3D
to Denver, BTW.........
Best
Jonathan
Jonathan Kaplan
curator
Plinth Gallery
3520 Brighton Blvd
Denver, CO 80216
www.plinthgallery.com
303 295-0717 =3D20
Richard Burkett on sun 6 nov 11
I agree with Jonathan that Darvan 811 works best overall, especially with=
=3D
=3D20
difficult to deflocculate slips (or glazes) like redware or terra cotta c=
=3D
lays. Both=3D20
varieties of Darvan (7 and 811) offer a bit more freedom from the sins of=
=3D
=3D20
over- or under-deflocculation. I have a few glazes that I deflocculate in=
=3D
stead=3D20
of the more common need to flocculate glazes that settle badly. Rheology,=
=3D
=3D20
especially in glazes, seems to be somewhat of an arcane science/art that=3D=
20=3D
sometimes requires the addition of both a deflocculant and a flocculant w=
=3D
hich=3D20
offer different changes to the viscosity and the settling properties of t=
=3D
he=3D20
slip/glaze.
Flocculation and deflocculation are both reversible. For example, try add=
=3D
ing a=3D20
few drops of acid (vinegar works and is safe) to a small amount of=3D20
deflocculated casting slip - it instantly thickens. Porcelain and similar=
=3D
=3D20
whiteware bodies often have slight deflocculation from the leaching of so=
=3D
dium=3D20
from the feldspar (nepheline syenite is even worse about leaching sodium)=
=3D
.=3D20
Adding vinegar to a such a partially 'naturally deflocculated' porcelain =
=3D
reverses=3D20
(at least temporarily) the deflocculation, making the porcelain more seem=
=3D
=3D20
more plastic. I had some commercially prepared B-mix a few years ago that=
=3D
=3D20
was miserable to throw, but slicing it into thin slabs, spraying the slab=
=3D
s with=3D20
concentrated vinegar (from Asian groceries), then re-wedging made the cla=
=3D
y=3D20
both more plastic, and actually stiffer even though I'd added moisture =3DE=
2=3D
=3D80=3D93 proof=3D20
that some ingredient the clay supplier was adding was partially defloccul=
=3D
ating=3D20
the B-mix.
On Sat, 5 Nov 2011 08:15:45 -0600, jonathan kaplan=3D20
wrote:
>There are a few types of Darvan products available from RT Vanderbilt.
>
>My experience is that their Darvan 811 is a far superior product for=3D20
deflocculation than Darvan 7. Their chemistry is different in that one is=
=3D
a long=3D20
chained polymer and the other a short chained polymer. The are both sodiu=
=3D
m=3D20
polyacrylates.
>
>I have used the 811 product in terra cotta casting slips as well as both=
=3D
=3D20
porcelains and whitewares. and purchase directly from RT Vanderbilt in=3D20=
=3D
approximately 5 gallon plastic pails. They do not ship in cold weather to=
=3D
=3D20
Denver, BTW.........
>
>Best
>
>Jonathan
>
>Jonathan Kaplan
>curator
>
>Plinth Gallery
>3520 Brighton Blvd
>Denver, CO 80216
>
>www.plinthgallery.com
>303 295-0717=3D20=3D20
Craig Edwards on sun 6 nov 11
Hello Richard and all: Do you mean yield and mobility, rather than
viscosity? I have always used viscosity in relation to how glazes are in
the melt, but then the meanings of terms change all the time.
Make Good Pots
~Craig
New London MN
http://woodfiredpottery.blogspot.com/
On Sat, Nov 5, 2011 at 11:43 PM, Richard Burkett
wrote:
Rheology,
>
> especially in glazes, seems to be somewhat of an arcane science/art that
> sometimes requires the addition of both a deflocculant and a flocculant
> which
> offer different changes to the viscosity and the settling properties of t=
he
> slip/glaze.
>
>
--
Richard Burkett on sun 6 nov 11
Hi Craig,
I suppose one could use the terms yield and mobility (although that seems=
=3D
=3D20
more like a term that would infer the glaze has the ability to get up and=
=3D
move=3D20
around on its own!) to describe the flow characteristics of the slip.=3D20
Viscosimeters (or viscometers) are typically the device used to measure=3D2=
0=3D
viscosity of slips, so I'd say viscosity is the more accurate term. It wo=
=3D
uld=3D20
apply to any fluid, including melted glaze or glass.
Best,
Richard
http://richardburkett.com
http://sdpotterytour.com
http://hyperglaze.com
http://ecuadorpottery.com
On Sun, 6 Nov 2011 08:27:47 -0600, Craig Edwards=3D20
wrote:
>Hello Richard and all: Do you mean yield and mobility, rather than
>viscosity? I have always used viscosity in relation to how glazes are =
=3D
in
>the melt, but then the meanings of terms change all the time.
>
>Make Good Pots
>~Craig
>New London MN
>http://woodfiredpottery.blogspot.com/
>
>On Sat, Nov 5, 2011 at 11:43 PM, Richard Burkett
>wrote:
>
> Rheology,
>>
>> especially in glazes, seems to be somewhat of an arcane science/art th=
=3D
at
>> sometimes requires the addition of both a deflocculant and a flocculan=
=3D
t
>> which
>> offer different changes to the viscosity and the settling properties o=
=3D
f the
>> slip/glaze.
>>
>>
>
>
>
>
>
>
>
>
>
>--
Craig Edwards on sun 6 nov 11
Richard: Thank you for clearing this up for me. I am now confused on what
term to use to describe how runny a glaze is when it melts in firing. I
always assumed that a glaze in batch was a colloidal suspension, and a
fluid in the melt. Help!!!!!
--
Make Good Pots
~Craig
New London MN
http://woodfiredpottery.blogspot.com/
On Sun, Nov 6, 2011 at 8:00 AM, Richard Burkett w=
rote:
> Hi Craig,
> I suppose one could use the terms yield and mobility (although that seems
> more like a term that would infer the glaze has the ability to get up and
> move
> around on its own!) to describe the flow characteristics of the slip.
> Viscosimeters (or viscometers) are typically the device used to measure
> viscosity of slips, so I'd say viscosity is the more accurate term. It
> would
> apply to any fluid, including melted glaze or glass.
>
> Best,
>
> Richard
>
> http://richardburkett.com
> http://sdpotterytour.com
> http://hyperglaze.com
> http://ecuadorpottery.com
>
> On Sun, 6 Nov 2011 08:27:47 -0600, Craig Edwards
> wrote:
>
> >Hello Richard and all: Do you mean yield and mobility, rather than
> >viscosity? I have always used viscosity in relation to how glazes are =
in
> >the melt, but then the meanings of terms change all the time.
> >
> >Make Good Pots
> >~Craig
> >New London MN
> >http://woodfiredpottery.blogspot.com/
> >
> >On Sat, Nov 5, 2011 at 11:43 PM, Richard Burkett
> >wrote:
> >
> > Rheology,
> >>
> >> especially in glazes, seems to be somewhat of an arcane science/art th=
at
> >> sometimes requires the addition of both a deflocculant and a flocculan=
t
> >> which
> >> offer different changes to the viscosity and the settling properties o=
f
> the
> >> slip/glaze.
> >>
> >>
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >--
>
--
Make Good Pots
~Craig
New London MN
http://woodfiredpottery.blogspot.com/
John Hesselberth on mon 7 nov 11
Craig,
Use melt viscosity and dispersion or suspension viscosity if you are concer=
n=3D
ed you will confuse.
Regards,
John
Sent from my iPad
On Nov 6, 2011, at 9:00 AM, Craig Edwards wrote:
> Richard: Thank you for clearing this up for me. I am now confused on what
> term to use to describe how runny a glaze is when it melts in firing. I
> always assumed that a glaze in batch was a colloidal suspension, and a
> fluid in the melt. Help!!!!!
>=3D20
> --
>=3D20
> Make Good Pots
> ~Craig
> New London MN
> http://woodfiredpottery.blogspot.com/
>=3D20
> On Sun, Nov 6, 2011 at 8:00 AM, Richard Burkett >=3D
wrote:
>=3D20
>> Hi Craig,
>> I suppose one could use the terms yield and mobility (although that seem=
s=3D
>> more like a term that would infer the glaze has the ability to get up an=
d=3D
>> move
>> around on its own!) to describe the flow characteristics of the slip.
>> Viscosimeters (or viscometers) are typically the device used to measure
>> viscosity of slips, so I'd say viscosity is the more accurate term. It
>> would
>> apply to any fluid, including melted glaze or glass.
>>=3D20
>> Best,
>>=3D20
>> Richard
>>=3D20
>> http://richardburkett.com
>> http://sdpotterytour.com
>> http://hyperglaze.com
>> http://ecuadorpottery.com
>>=3D20
>> On Sun, 6 Nov 2011 08:27:47 -0600, Craig Edwards
>> wrote:
>>=3D20
>>> Hello Richard and all: Do you mean yield and mobility, rather than
>>> viscosity? I have always used viscosity in relation to how glazes are=
i=3D
n
>>> the melt, but then the meanings of terms change all the time.
>>>=3D20
>>> Make Good Pots
>>> ~Craig
>>> New London MN
>>> http://woodfiredpottery.blogspot.com/
>>>=3D20
>>> On Sat, Nov 5, 2011 at 11:43 PM, Richard Burkett
>>> wrote:
>>>=3D20
>>> Rheology,
>>>>=3D20
>>>> especially in glazes, seems to be somewhat of an arcane science/art th=
a=3D
t
>>>> sometimes requires the addition of both a deflocculant and a flocculan=
t=3D
>>>> which
>>>> offer different changes to the viscosity and the settling properties o=
f=3D
>> the
>>>> slip/glaze.
>>>>=3D20
>>>>=3D20
>>>=3D20
>>>=3D20
>>>=3D20
>>>=3D20
>>>=3D20
>>>=3D20
>>>=3D20
>>>=3D20
>>>=3D20
>>> --
>>=3D20
>=3D20
>=3D20
>=3D20
> --
> Make Good Pots
> ~Craig
> New London MN
> http://woodfiredpottery.blogspot.com/
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