Axner on sat 6 apr 96
Dear Charles,
Darvan 7 is a defloculent for slip. In a slip, you need a few drops per
gallon. In glaze, use about a teaspoon for 100 pounds of glaze to act as a
suspending agent. I guess you can also use a few drops in your throwing
water (as per Clayart) to make it more slick.
Axner Company carries Darvan 7.
Judy at Axner
Chris Schafale on fri 7 may 99
Darvan 7 is a deflocculant, mostly used in slips. It is described as
a "polyacrylate" -- whatever that is -- and it's supposed to be a
bit less fussy to use (harder to overdo it) than soda ash/sodium
silicate combinations. All I know is, it also works great in glazes
that are flocculated and need to be thinned.
Chris
> ----------------------------Original message----------------------------
> WHAT IS DARVAN 7?
> -----Original Message-----
> From: Carolynn Palmer
> To: CLAYART@LSV.UKY.EDU
> Date: Tuesday, May 04, 1999 5:15 PM
> Subject: A mystery/Glaze thickness/"Magic"
>
>
> >----------------------------Original message----------------------------
> >Yesterday I visited a "slip cast" commercial pottery that makes the ware
> >florists use to put their arrangements in. They fire everything to cone 05,
> >bisque and glaze fire both.
> >
> >During this visit, the owner showed me his glazing area, with these vats
> (of
> >about 8-10 gallon capacity) of glaze they dip the ware in. He asked me if
> I
> >mixed my own glazes and and when I said, of course. He said he wanted to
> >show me his "Magic Solution" for thickening glazes. He stirred up a batch
> of
> >glaze and added about 1/2 to 1 cup of a heavy cloudy liquid from a squeeze
> >bottle, continued stirring and the whole batch of glaze thickened up
> >instantly for a thicker glaze application to the pieces they were dipping.
> >
> >Then he said, Ok, now if he wants it to be a thinner coat of glaze for the
> >remaining pieces, he just stirs in some liquid (which I correctly guessed
> was
> >Darvan 7) out of another squeeze bottle and the glaze went back to its
> >original consistency.
> >
> >He wouldn't tell me what his "Magic Solution" was, but offered to sell me
> >some at what I felt was an exhorbitant price.
> >
> >Any guesses as to what his "Magic Solution" is?
> >
> >Carolynn Palmer, Somerset Center, Michigan
> >
>
>
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
Robert Santerre on sun 9 may 99
Chris, now you've got me confused. My understanding was that darvan 7 is used i
molding slips and glazes to improve flow characteristics and coverage. Now you'
telling me you use it to "thin" a glaze mix? So are you saying that in an
over-flocculated glaze mix (one that is too thick/viscous for proper application
darvan 7 can be added instead of water (or along with water) to "thin" the glaze
to a proper workable viscosity and not have the glaze components settle to the
bottom of the bucket and form a rock-hard precipitate (if only water had been
used)? Or have I completely mis-understood your application?
Bob
////////////////////////////////////////////////////////////////////////////////
Chris Schafale wrote:
> ----------------------------Original message----------------------------
> Darvan 7 is a deflocculant, mostly used in slips. It is described as
> a "polyacrylate" -- whatever that is -- and it's supposed to be a
> bit less fussy to use (harder to overdo it) than soda ash/sodium
> silicate combinations. All I know is, it also works great in glazes
> that are flocculated and need to be thinned.
>
> Chris
>
> > ----------------------------Original message----------------------------
> > WHAT IS DARVAN 7?
> > -----Original Message-----
> > From: Carolynn Palmer
> > To: CLAYART@LSV.UKY.EDU
> > Date: Tuesday, May 04, 1999 5:15 PM
> > Subject: A mystery/Glaze thickness/"Magic"
> >
> >
> > >----------------------------Original message----------------------------
> > >Yesterday I visited a "slip cast" commercial pottery that makes the ware
> > >florists use to put their arrangements in. They fire everything to cone 05,
> > >bisque and glaze fire both.
> > >
> > >During this visit, the owner showed me his glazing area, with these vats
> > (of
> > >about 8-10 gallon capacity) of glaze they dip the ware in. He asked me if
> > I
> > >mixed my own glazes and and when I said, of course. He said he wanted to
> > >show me his "Magic Solution" for thickening glazes. He stirred up a batch
> > of
> > >glaze and added about 1/2 to 1 cup of a heavy cloudy liquid from a squeeze
> > >bottle, continued stirring and the whole batch of glaze thickened up
> > >instantly for a thicker glaze application to the pieces they were dipping.
> > >
> > >Then he said, Ok, now if he wants it to be a thinner coat of glaze for the
> > >remaining pieces, he just stirs in some liquid (which I correctly guessed
> > was
> > >Darvan 7) out of another squeeze bottle and the glaze went back to its
> > >original consistency.
> > >
> > >He wouldn't tell me what his "Magic Solution" was, but offered to sell me
> > >some at what I felt was an exhorbitant price.
> > >
> > >Any guesses as to what his "Magic Solution" is?
> > >
> > >Carolynn Palmer, Somerset Center, Michigan
> > >
> >
> >
> Light One Candle Pottery
> Fuquay-Varina, NC
> candle@intrex.net
Tom Wirt on sun 9 may 99
>----------------------------Original message----------------------------
>Chris, now you've got me confused. My understanding was that darvan 7 is
used i
>molding slips and glazes to improve flow characteristics and coverage. Now
you'
>telling me you use it to "thin" a glaze mix? So are you saying that in an
>over-flocculated glaze mix (one that is too thick/viscous for proper
application
>darvan 7 can be added instead of water (or along with water) to "thin" the
glaze
>to a proper workable viscosity and not have the glaze components settle to
the
>bottom of the bucket and form a rock-hard precipitate (if only water had
been
>used)? Or have I completely mis-understood your application?
>
>Bob
Hi Bob,
Jumping in here, yes, Darvan 7 is a deflocculant, used to suspend a glaze or
slip slop, allowing higher solids to water ratio, while retaining apparent
flow. It could be used to correct an over flocculated slop.
The primary ingredient upon which it acts, is the clay. This is a reason why
most glaze recipes call for some clay. Clay particles are electrically
charged and either attract or repel each other. Deflocculants encourage
repulsion and therefore help "float" the suspension. It is this float that
gives the appearance of thinness.
In glazes, one way to test how much defloc to add is to dip a piece of
bisque in the deflocced glaze. There will come a point where the glaze
doesn't want to dry. That's where you've over deflocculated the glaze. If
a particular glaze is still settling too much, you may need to add a bit
more Bentonite or ball clay to get enough clay to float the rest of the
ingredients. But not over 1-2% Bentonite.
We've been working to dewater Moonlight to stop the crawling problems we've
had. SO we let it settle, take off the top water, and then add some Darvan
7 to keep it thin enough to work with.
Hope this helps.
Tom Wirt
Chris Schafale on mon 10 may 99
Hi Bob,
Yup, that's exactly what I'm saying. Seems to work great, especially
in glazes with lots of Gerstley borate that get too viscous to dip
properly.
You remove as much water as you can, add a little bit of
Darvan 7 until you feel the glaze get more fluid, then if needed you
can add back more water to get the specific gravity you want. I
will caution that you may only need a very little for this to work.
In a recent 5000 gram glaze batch, I added 5 cc (using a veterinary
syringe) and that was enough to do what needed to be done. I usually
add it 1 cc at a time, stirring thoroughly and waiting at least a
couple of minutes between additions.
You can test for viscosity after each addition by sticking a dry
finger in the glaze, pulling it out, and noticing how many drips fall
from it. A very viscous, flocculated glaze may not drip at all,
while a very runny, possibly over deflocculated one will run off in
streams. Two or three drips seems to work pretty well for me. And,
no, I have not experienced settling to be a problem at all when using
Darvan 7 in this way (of course, I wouldn't be using it in the first
place if the glaze were one that is prone to settling). I have no
experience with using Darvan 7 in combination with suspenders like
bentonite or flocculants like epsom salts, so I can't comment on what
would happen in these situations.
I've just told you absolutely everything I know about Darvan 7, so if
you have other questions, maybe Ron Roy (who suggested it to me in
the first place) or someone else could help.
Chris
> ----------------------------Original message----------------------------
> Chris, now you've got me confused. My understanding was that darvan 7 is used
> molding slips and glazes to improve flow characteristics and coverage. Now yo
> telling me you use it to "thin" a glaze mix? So are you saying that in an
> over-flocculated glaze mix (one that is too thick/viscous for proper applicati
> darvan 7 can be added instead of water (or along with water) to "thin" the gla
> to a proper workable viscosity and not have the glaze components settle to the
> bottom of the bucket and form a rock-hard precipitate (if only water had been
> used)? Or have I completely mis-understood your application?
>
> Bob
>
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
John Jensen on mon 10 may 99
I've been using a defloculated slip to assemble parts..leatherhard clay to
leatherhard clay. Just guessing at amounts of sodium silicate and sodium
carbonate. Today I mixed up about a five gallon batch using Darvan 7.
First I added a couple of oz to a few gallons of water and then began adding
clay and stirring with a drywall stirring propeller till it was seemingly
pretty thick..like melted icecream.
I have no particular wisdom on this subject..I might have the wrong Ideas
altogether. But it seems to work.
John Jensen, mudbug@toad.net
Mudbug Pottery
Annapolis, Md.
Janet H Walker on mon 10 may 99
...over-flocculated glaze mix...
...one that is too thick/viscous for proper application...
Hey Bob! Hold your horses a sec. "Thick" and "viscous" can have
different meanings! And different solutions!
1. Glaze that is thick because of high s.g. is one thing. It
could take more water in order to leave the right thickness of
glaze coating on the pot.
2. Glaze that is thick because of flocculation is another thing.
The s.g. may be just right for application in the water content
sense but getting it onto the pot may be a pain. This one can use a
deflocculant in order to make it flow enough for whatever kind of
glaze application you need. This is where you add Darvan 7.
The only way to tell the difference between case 1 and case 2 is to
measure the s.g. Weigh 100 ml volume of the glaze on a gram scale
and divide by 100. Keep doing this over time and you'll learn what
number you want.
I had an experience just yesterday with a scrap glaze that acted so
thick when I stirred it that I was about to grab the water bottle.
Then I thought, well find out the s.g. so you can calculate how much
water to add. I weighed the stuff and found out that it was
actually BELOW the s.g. I like to have for my glazes.
How did that happen you ask? Well, I always use bentonite in my
glazes (flocculant) and I've been using a lot of high soda glazes
(flocculant) and so the scrap glaze has a good chance of being like
those parent glazes. Anyhow, 5 ml of Darvan 7 squirted into the
gallon of glaze had an immediate impact. It then stirred like
water. Until the Darvan got all dispersed and the glaze thickened
up again. now I think the glaze could use another squirt next time
I use it.
So, that's the story as I see it.
Cheers,
Jan Walker
Cambridge MA USA
John Rodgers on wed 2 nov 11
Randall,
I never understood why Darvan in the first place. Way back there I tried
it, and wasn't impressed. Went back to using sodium silicate and have
used it exclusively for years .
John
John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com
On 11/2/2011 1:43 PM, Randall Moody wrote:
> Is there a shortage on Darvan 7? Are they going to stop making it? Has
> anyone heard anything about this?
>
> --
> Randall in Atlanta
> http://wrandallmoody.com
>
>
Randall Moody on wed 2 nov 11
Is there a shortage on Darvan 7? Are they going to stop making it? Has
anyone heard anything about this?
--
Randall in Atlanta
http://wrandallmoody.com
Randall Moody on thu 3 nov 11
My studio mate likes Darvan 7 better than the sodium silicate. She
hasn't had good luck with the sodium silicate and since she is in her
thesis year it is a bit late to figure out why it isn't working.
On Wed, Nov 2, 2011 at 11:57 PM, John Rodgers wrote:
> Randall,
>
> I never understood why Darvan in the first place. Way back there I tried =
it,
> and wasn't impressed. Went back to using sodium silicate and have used it
> exclusively for years .
>
> John
>
> John Rodgers
> Clayartist and Moldmaker
> 88'GL VW Bus Driver
> Chelsea, AL
> Http://www.moldhaus.com
>
>
> On 11/2/2011 1:43 PM, Randall Moody wrote:
>>
>> Is there a shortage on Darvan 7? Are they going to stop making it? Has
>> anyone heard anything about this?
>>
>> --
>> Randall in Atlanta
>> http://wrandallmoody.com
>>
>>
>
>
--
Randall in Atlanta
http://wrandallmoody.com
John Britt on thu 3 nov 11
I always thought it was sodium silicate and soda ash because they work on=
=3D
=3D20
different part of the atom.
There are tons of deflocculants. Darvan 811?
www.facebook.com/john.britt1
jonathan byler on thu 3 nov 11
Darvan is supposed to be less sensitive to the effects of over or
under application as sodium silicate is. i.e. if you put a little too
much in and it doesn't cause the slip to gel so much as sodium
silicate does. it is also supposed to be less corrosive to your molds
than sodium silicate. new technology is often better. sometimes
not. but in this case yes.
On Nov 2, 2011, at 10:57 PM, John Rodgers wrote:
> Randall,
>
> I never understood why Darvan in the first place. Way back there I
> tried
> it, and wasn't impressed. Went back to using sodium silicate and have
> used it exclusively for years .
>
> John
>
> John Rodgers
> Clayartist and Moldmaker
> 88'GL VW Bus Driver
> Chelsea, AL
> Http://www.moldhaus.com
>
>
> On 11/2/2011 1:43 PM, Randall Moody wrote:
>> Is there a shortage on Darvan 7? Are they going to stop making it?
>> Has
>> anyone heard anything about this?
>>
>> --
>> Randall in Atlanta
>> http://wrandallmoody.com
>>
>>
Philip Poburka on thu 3 nov 11
I always thought 'Darvan 7' sounded like an early Startrek episode Planet
name.
----- Original Message -----
From: "John Rodgers"
> Randall,
>
> I never understood why Darvan in the first place. Way back there I tried
> it, and wasn't impressed. Went back to using sodium silicate and have
> used it exclusively for years .
>
> John
Eleanora Eden on fri 4 nov 11
The blurb in my old Laguna catalog says:
A deflocculant that is user friendly because it has a wider deflocculation
curve. Does not deteriorate molds as actively as does sodium silicate.
That's where I got my idea that it was better than sodium silicate. I boug=
ht
a gallon years ago so I am immune from a discontinuation. But why would
such a product be discontinued?
If I was running the universe there would be a sign up list with suppliers
that certain products were of great value and the customer would be notifie=
d
in plenty of time to make a last order before it was discontinued.
Eleanora
>Darvan is supposed to be less sensitive to the effects of over or
>under application as sodium silicate is. i.e. if you put a little too
>much in and it doesn't cause the slip to gel so much as sodium
>silicate does. it is also supposed to be less corrosive to your molds
>than sodium silicate. new technology is often better. sometimes
>not. but in this case yes.
The past is not dead. It is not even past.
--
Bellows Falls Vermont
www.eleanoraeden.com
jonathan byler on fri 4 nov 11
they might have discontinued because there is a newer and better
product with an even wider deflocculation curve on the market. I
think darvan 811 might fit the bill, but I am not an expert in the
field of deflocculants. why would a company continue to operate two
product lines, when they could only operate one? I'm sure the
industrial ceramics end users have been notified as to why darvan 7 is
discontinued (if it has been discontinued) - one must remember that
all of the art/craft/hobby ceramics people in the world are probably
not a drop in the bucket in terms of materials demand/usage compared
with the largest industrial/commercial producers.
On Nov 4, 2011, at 10:07 AM, Eleanora Eden wrote:
> The blurb in my old Laguna catalog says:
>
> A deflocculant that is user friendly because it has a wider
> deflocculation
> curve. Does not deteriorate molds as actively as does sodium
> silicate.
>
> That's where I got my idea that it was better than sodium silicate.
> I bought
> a gallon years ago so I am immune from a discontinuation. But why
> would
> such a product be discontinued?
>
> If I was running the universe there would be a sign up list with
> suppliers
> that certain products were of great value and the customer would be
> notified
> in plenty of time to make a last order before it was discontinued.
>
> Eleanora
>
>
>
>> Darvan is supposed to be less sensitive to the effects of over or
>> under application as sodium silicate is. i.e. if you put a little
>> too
>> much in and it doesn't cause the slip to gel so much as sodium
>> silicate does. it is also supposed to be less corrosive to your
>> molds
>> than sodium silicate. new technology is often better. sometimes
>> not. but in this case yes.
>
>
>
> The past is not dead. It is not even past.
>
> --
> Bellows Falls Vermont
> www.eleanoraeden.com
L TURNER on fri 4 nov 11
Darvan is a branded product from R.T. Vanderbilt Company, Inc.
links:
http://www.rtvanderbilt.com/ceramics.htm
and specifically to the range of Darvan products:
http://www.rtvanderbilt.com/DARVAN_Dispersing_Agents_TDS_Web.pdf
L. Turner
The Woodlands, TX
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