Bill Walker on tue 2 sep 97
Liquid starch will not work as a deflocculant. It will thicken your
slip. The Darvon you get at the pharmacy is not the same thing as
the Darvan that is a deflocculant, which you can get from many clay
distributers. Some people use Calgon, which you can get at a grocery
store, as a deflocculant. I have never tried it. In the old days,
when using Calgon as a deflocculant was more common, it contained
phosphates. Then they decided (in the late 1960s ?) that phosphates
were an environmental hazard and the composition changed. Nowadays,
I believe the composition of Calgon depends on which state you live in.
So it is likely that Calgon from some places is a better deflocculant
that Calgon from other places.
Bill Walker
Alfred, NY USA
walkerw@bigvax.alfred.edu
>From: Jo Gilder
>----------------------------Original message----------------------------
>Could someone please tell me what this is? I understand what it's
>supposed to do but I don't know where I can find it. Can I buy it in a
>grocery store (liquid starch), a pharmacy (Darvan) or do I have to go to
>a clay supply distributor(Sodium Silicate)? Are there common everyday
>things that I can use that have the same properties?
>
>Jo
Bill Walker on fri 5 sep 97
As someone who claims to have more chemistry savvy, I would like
to tell Vince that his explanation is right on, except for one point.
Not all deflocculants are alkaline. An example is Darvan, which is
a neutral salt of polyacrylic acid. (remember chemistry, acid + base
= salt) The active part of Darvan is the polyacrylic acid, a long
stringy molecule that is negatively charged all along its length. It
sticks to the particle surfaces, making the surfaces effectively
negatively charged, and causes the particles to repel each other.
Bill Walker
Alfred NY USA
Vince Pitelka wrote:
>----------------------------Original message----------------------------
>At 06:46 AM 9/2/97 -0400, you wrote:
>>----------------------------Original message----------------------------
>>Vinegar is sometimes used as a deflocculant - plain old white vinegar.
>
>This is misleading. Vinegar is acidic, and therefore will not act as a
>deflocculant. Someone with more chemistry savvy, of which there are plenty
>on this list, can explain it better, but my understanding is that the
>deflocculants are all alkaline, and introduce like electrical charges to the
>particles in suspension, causing the particles to repel one another and
>remain in liquid suspension with less water content. An acidic material
>will introduce opposite electrical charges, causing the particles to "flock"
>together. This will thicken a given glaze or slip which may have been
>slightly alkaline before deflocculation, and thus may well reduce settling,
>but in a thinner mixture it will increase settling.
>- Vince
>
>Vince Pitelka - vpitelka@DeKalb.net
>Home 615/597-5376, work 615/597-6801, fax 615/597-6803
>Appalachian Center for Crafts
>1560 Craft Center Drive, Smithville TN 37166
M Richens on sat 13 sep 97
Hi
Just my 2p..
The action as a deflocculant is a measure of how well it combines with
free ions in the slip. Most of the phoshates are strong deflocculants,
Tetra sodium pyrophoshates, Sodium hexa-metaphosphate (Calgon as was)
they work as water softeners. The danger of them is is that they will
carry on working. A little added to up the fluidity of a slip and you
will possibly have a runny slip for good; one that you need to floc to a
pudding state to stop it running off your bisque. One of the acid
deflocculants is Citric acid (from your druggist or home-brew shop).
But.. you can end up with everything set in the bottom of your storage
jar quite hard to remix.
HTH
Max
--
Max Richens max@richens.demon.co.uk +44 (0) 1925756241
Enamel Consultant - Ceramist - Analyst programmer
Software for Batch Formulation and Millroom control.
William Hendry on sun 28 jul 02
I am using a heavily fritted glaze sieved at 200 mesh for spraying and =
need to determine the best deflocculent to be using.
What are the pros and cons of using sodium silicate vs sodium carbonate?
Regarding how much to use: As sodim carbonate is a dry material it is =
easy to figure out how much to use. But when using sodium silicate, as =
it is a liquid, do you determine the amount by multiplying .001 by =
the volume of the liquid glaze? For example, if you have 500ml of wet =
glaze, would you then add .5ml of sodium silicate? What if you later =
add more water to the glaze to thin it, would you have to add more =
deflocculent too?
Thanks
William
Ceramic Design Group on sun 28 jul 02
on 7/28/02 8:08 AM, William Hendry at whendry@CHARTER.NET wrote:
> I am using a heavily fritted glaze sieved at 200 mesh for spraying and =
> need to determine the best deflocculent to be using.
> What are the pros and cons of using sodium silicate vs sodium carbonate?
We use a very (read VERY) small amount of Darvan 811 to help with this as
well as to obtain a better glaze poise.
Jonathan
Jonathan Kaplan, president
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
voice and fax 970 879-9139
info@ceramicdesigngroup.net
Plant Location:
1280 13th Street Unit 13
Steamboat Springs CO 80487
(please use this address for all deliveries via UPS, comman carrier, Fed Ex,
etc.)
"Custom design and manufacturing for the ceramic arts, giftware and pottery
industries. Molds, models, and tooling for slip casting, jiggering and
hydraulic pressing. Consultation on clay and glaze formulation, production
systems,firing, and kilns.
Marni Turkel on mon 29 jul 02
As long as we are talking about deflocculating glazes:
I use Darvan 811 to deflocculate two of my glazes (maybe 5 drops in a
5 gallon bucket to start), but find that when I let the glaze sit for
a few days or a week I need to add more deflocculant to get back the
fluidity. Over a period of a month or two with adding a bit more each
time, I assume this gives me an accumulation of deflocculant but I
have never noticed any particular problem until a few days ago. I
went to stir up a bucket that hadn't been used for 3 to 4 weeks and
it was almost hard.I've never seen this happen with any glaze. It was
too bizarre. I was able to get it to a partially liquid state by
jabbing at it for awhile with the blunger and then added some more
Darvan 811 which yielded a pudding-like mass with CHUNKS! More Darvan
(quite a large amount more) finally yielded an acceptable slurry, but
I still got a lot of cracking in the glaze as it dried, which is why
I added deflocculant to start with. After getting it moving, I
checked the specific gravity and that was in the normal range, so
evaporation of water was not an issue.
Part way through this episode, I started thinking I had cumulatively
over-deflocculated this batch and tried adding a little vinegar to a
test amount, but that had no effect. So I proceeded to add more
Darvan. The bucket is currently sitting in the "I'll deal with this
later" corner.
I was wondering if there would be a difference if I used Darvan 7.
The literature for the two specifies that Darvan 7 was created for
glazes and that Darvan 811 is for claybodies. I am using 811 only
because that is what I have in the studio for my casting body.
Has anyone had a similar experience? Any ideas of what is happening?
My suppier is currently searching for another source of copper
carbonate (this one comes from France) since that is the cause of the
flocculation in this particular glaze. But I would still like to
understand deflocculating glazes better that I do now.
Marni
--
Marni Turkel
Stony Point Ceramic Design
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone: 707-579-5567
Fax: 707-579-1116
http://www.marniturkel.com
Marni Turkel on tue 30 jul 02
William,
You're right, it may by over-deflocculated. I am going to add a small
amount of this weird batch to an un-deflocculated batch (not the
whole clean batch, just a quart or so) to see if it has an effect.
I think bentonite would have the opposite to what I want. My glaze
doesn't settle, it is pudding-like, that's why I started using
Darvan. I had replaced the kaolin with calcined kaolin so time back.
It isn't the glaze formula, something in the copper carbonate is
jelling this glaze up. This same base with other colorants doesn't
jell.
Marni
>From: William Hendry
>Marni
>
>I've not used the Darvan products but have had the same drop-out/hardening
>issue with sodium silicate. I have heard that too much of a deflocculant
>will cause the opposite reaction so maybe that is what we're seeing. How
>about the use of plain ol' bentonite, isn't that supposed to be a good
>deflocculant, or are these other products supposedly superior?
>
>William
--
Marni Turkel
Stony Point Ceramic Design
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone: 707-579-5567
Fax: 707-579-1116
http://www.marniturkel.com
William Hendry on tue 30 jul 02
Marni
I've not used the Darvan products but have had the same drop-out/hardening
issue with sodium silicate. I have heard that too much of a deflocculant
will cause the opposite reaction so maybe that is what we're seeing. How
about the use of plain ol' bentonite, isn't that supposed to be a good
deflocculant, or are these other products supposedly superior?
William
----- Original Message -----
From: "Marni Turkel"
To:
Sent: Tuesday, July 30, 2002 12:10 AM
Subject: Re: deflocculants
> As long as we are talking about deflocculating glazes:
>
> I use Darvan 811 to deflocculate two of my glazes (maybe 5 drops in a
> 5 gallon bucket to start), but find that when I let the glaze sit for
> a few days or a week I need to add more deflocculant to get back the
> fluidity. Over a period of a month or two with adding a bit more each
> time, I assume this gives me an accumulation of deflocculant but I
> have never noticed any particular problem until a few days ago. I
> went to stir up a bucket that hadn't been used for 3 to 4 weeks and
> it was almost hard.I've never seen this happen with any glaze. It was
> too bizarre. I was able to get it to a partially liquid state by
> jabbing at it for awhile with the blunger and then added some more
> Darvan 811 which yielded a pudding-like mass with CHUNKS! More Darvan
> (quite a large amount more) finally yielded an acceptable slurry, but
> I still got a lot of cracking in the glaze as it dried, which is why
> I added deflocculant to start with. After getting it moving, I
> checked the specific gravity and that was in the normal range, so
> evaporation of water was not an issue.
>
> Part way through this episode, I started thinking I had cumulatively
> over-deflocculated this batch and tried adding a little vinegar to a
> test amount, but that had no effect. So I proceeded to add more
> Darvan. The bucket is currently sitting in the "I'll deal with this
> later" corner.
>
> I was wondering if there would be a difference if I used Darvan 7.
> The literature for the two specifies that Darvan 7 was created for
> glazes and that Darvan 811 is for claybodies. I am using 811 only
> because that is what I have in the studio for my casting body.
>
> Has anyone had a similar experience? Any ideas of what is happening?
>
> My suppier is currently searching for another source of copper
> carbonate (this one comes from France) since that is the cause of the
> flocculation in this particular glaze. But I would still like to
> understand deflocculating glazes better that I do now.
>
> Marni
> --
>
> Marni Turkel
> Stony Point Ceramic Design
> 2080 Llano Rd 1B
> Santa Rosa, CA 95407
>
> Phone: 707-579-5567
> Fax: 707-579-1116
> http://www.marniturkel.com
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Autumn Downey on tue 30 jul 02
Hi Marni,
Sounds like not fun at all. This might be the time to let things settle
out and then pour off the liquid and add new water!
I'm not sure I'd try bentonite, as you might have a jelly-like glaze that
never dried!! (Bentonite and I do not get along most of the time.)
Maybe someone on Clayart (sounds suspiciously like Ron Roy) could look at
the recipe and figure out another way to arrive at the same glaze with
different ingredients/clays?
I've had occasional bouts with awkward glazes that need something - and
sometimes it's hard to tell what. I like Epsom's salts (in solution) for
flocculating.
Good luck!
Autumn Downey
At 09:04 AM 2002-07-30 -0400, you wrote:
>Marni
>
>I've not used the Darvan products but have had the same drop-out/hardening
>issue with sodium silicate. I have heard that too much of a deflocculant
>will cause the opposite reaction so maybe that is what we're seeing. How
>about the use of plain ol' bentonite, isn't that supposed to be a good
>deflocculant, or are these other products supposedly superior?
>
>William
>
Ababi on tue 30 jul 02
Isn't it all wrong? Don't you need flocculant for your glaze? Magnesium Sulfate?
---------- Original Message ----------
>Marni
>I've not used the Darvan products but have had the same drop-out/hardening
>issue with sodium silicate. I have heard that too much of a deflocculant
>will cause the opposite reaction so maybe that is what we're seeing. How
>about the use of plain ol' bentonite, isn't that supposed to be a good
>deflocculant, or are these other products supposedly superior?
>William
>----- Original Message -----
>From: "Marni Turkel"
>To:
>Sent: Tuesday, July 30, 2002 12:10 AM
>Subject: Re: deflocculants
>> As long as we are talking about deflocculating glazes:
>>
>> I use Darvan 811 to deflocculate two of my glazes (maybe 5 drops in a
>> 5 gallon bucket to start), but find that when I let the glaze sit for
>> a few days or a week I need to add more deflocculant to get back the
>> fluidity. Over a period of a month or two with adding a bit more each
>> time, I assume this gives me an accumulation of deflocculant but I
>> have never noticed any particular problem until a few days ago. I
>> went to stir up a bucket that hadn't been used for 3 to 4 weeks and
>> it was almost hard.I've never seen this happen with any glaze. It was
>> too bizarre. I was able to get it to a partially liquid state by
>> jabbing at it for awhile with the blunger and then added some more
>> Darvan 811 which yielded a pudding-like mass with CHUNKS! More Darvan
>> (quite a large amount more) finally yielded an acceptable slurry, but
>> I still got a lot of cracking in the glaze as it dried, which is why
>> I added deflocculant to start with. After getting it moving, I
>> checked the specific gravity and that was in the normal range, so
>> evaporation of water was not an issue.
>>
>> Part way through this episode, I started thinking I had cumulatively
>> over-deflocculated this batch and tried adding a little vinegar to a
>> test amount, but that had no effect. So I proceeded to add more
>> Darvan. The bucket is currently sitting in the "I'll deal with this
>> later" corner.
>>
>> I was wondering if there would be a difference if I used Darvan 7.
>> The literature for the two specifies that Darvan 7 was created for
>> glazes and that Darvan 811 is for claybodies. I am using 811 only
>> because that is what I have in the studio for my casting body.
>>
>> Has anyone had a similar experience? Any ideas of what is happening?
>>
>> My suppier is currently searching for another source of copper
>> carbonate (this one comes from France) since that is the cause of the
>> flocculation in this particular glaze. But I would still like to
>> understand deflocculating glazes better that I do now.
>>
>> Marni
>> --
>>
>> Marni Turkel
>> Stony Point Ceramic Design
>> 2080 Llano Rd 1B
>> Santa Rosa, CA 95407
>>
>> Phone: 707-579-5567
>> Fax: 707-579-1116
>> http://www.marniturkel.com
>>
>>
>____________________________________________________________________________
>__
>> Send postings to clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list or change your subscription
>> settings from http://www.ceramics.org/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
William Hendry on thu 1 aug 02
Marni,
Yes, bentonite would certainly add to the gelling you already have. And
someone else with whom I spoke confirmed (their opinion anyway) that too
much sodium silicate would cause flocculation. So maybe that's true with
Darvan as well. Do we know what Darvan, a name brand, really is in chemical
terms?
W
----- Original Message -----
From: "Marni Turkel"
To:
Sent: Wednesday, July 31, 2002 2:08 AM
Subject: Re: deflocculants
> William,
>
> You're right, it may by over-deflocculated. I am going to add a small
> amount of this weird batch to an un-deflocculated batch (not the
> whole clean batch, just a quart or so) to see if it has an effect.
>
> I think bentonite would have the opposite to what I want. My glaze
> doesn't settle, it is pudding-like, that's why I started using
> Darvan. I had replaced the kaolin with calcined kaolin so time back.
> It isn't the glaze formula, something in the copper carbonate is
> jelling this glaze up. This same base with other colorants doesn't
> jell.
>
> Marni
>
> >From: William Hendry
> >Marni
> >
> >I've not used the Darvan products but have had the same
drop-out/hardening
> >issue with sodium silicate. I have heard that too much of a deflocculant
> >will cause the opposite reaction so maybe that is what we're seeing. How
> >about the use of plain ol' bentonite, isn't that supposed to be a good
> >deflocculant, or are these other products supposedly superior?
> >
> >William
>
> --
>
> Marni Turkel
> Stony Point Ceramic Design
> 2080 Llano Rd 1B
> Santa Rosa, CA 95407
>
> Phone: 707-579-5567
> Fax: 707-579-1116
> http://www.marniturkel.com
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Marni Turkel on thu 1 aug 02
I have looked around the house for the literature on Darvan, but
can't find anything here, it is probably at the pottery. I get it
from R.F. Vanderbilt Company. I checked their website, but you have
to subscribe to see the MSDS on line. I'll try to see what I can find
at work.
Adding vinegar to my gloppy mess did nothing to reverse the process
if it is over-deflocculation.
On the other hand, while waiting to hear about a different source of
copper carbonate, I decided to test using red copper. After an
initial set-back, I looked back in the archives at a discussion that
mentioned red copper that cautioned that it is hard to disperse (I
can personally vouch for that now). I just happen to have a couple of
gallons of really good wetting agent on hand (just part of being an
involved orchid grower). At least I passed that hurdle.
Marni
William Hendry wrote:
>Yes, bentonite would certainly add to the gelling you already have. And
>someone else with whom I spoke confirmed (their opinion anyway) that too
>much sodium silicate would cause flocculation. So maybe that's true with
>Darvan as well. Do we know what Darvan, a name brand, really is in chemical
>terms?
--
Marni Turkel
Stony Point Ceramic Design
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone: 707-579-5567
Fax: 707-579-1116
http://www.marniturkel.com
Marni Turkel on fri 2 aug 02
William wrote:
>Marni, refresh my memory about what is going on with your glaze. Did you
>say that it was settling out AND like pudding?
About 2 years ago, one of my glazes that uses copper carbonate
started giving me trouble with gelling up and cracking as it dried.
This started with a new source of copper carb. It does not happen
with this same base with any other colorants. I use Darvan 811 to
deflocculate it, but find that when I let the glaze sit for a few
days or a week I need to add more deflocculant to get back the
fluidity. Over a period of a month or two with adding a bit more each
time, I assume this gives me an accumulation of deflocculant but I
have never noticed any particular problem until a few days ago. I
went to stir up a bucket that hadn't been used for 3 to 4 weeks and
it was almost hard.I've never seen this happen with any glaze. It was
too bizarre. I was able to get it to a partially liquid state by
jabbing at it for awhile with the blunger and then added some more
Darvan 811 which yielded a pudding-like mass with CHUNKS! More Darvan
(quite a large amount more) finally yielded an acceptable slurry, but
I still got a lot of cracking in the glaze as it dried, which is why
I added deflocculant to start with. After getting it moving, I
checked the specific gravity and that was in the normal range, so
evaporation of water was not an issue.
A follow-up on Darvan 7 & 811: it is described as a sodium
polyelectrolyte good for applications "where sodium oxide is not
detrimental". Does that tell you anything?
I have a call in to Vanderbilt to talk to the technical advisor on
Monday and I'll see what he can tell me.
Marni
--
Marni Turkel
Stony Point Ceramic Design
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone: 707-579-5567
Fax: 707-579-1116
http://www.marniturkel.com
William Hendry on fri 2 aug 02
Marni, refresh my memory about what is going on with your glaze. Did you
say that it was settling out AND like pudding?
William
----- Original Message -----
From: "Marni Turkel"
To:
Sent: Friday, August 02, 2002 2:40 AM
Subject: Re: deflocculants
> I have looked around the house for the literature on Darvan, but
> can't find anything here, it is probably at the pottery. I get it
> from R.F. Vanderbilt Company. I checked their website, but you have
> to subscribe to see the MSDS on line. I'll try to see what I can find
> at work.
>
> Adding vinegar to my gloppy mess did nothing to reverse the process
> if it is over-deflocculation.
>
>
> On the other hand, while waiting to hear about a different source of
> copper carbonate, I decided to test using red copper. After an
> initial set-back, I looked back in the archives at a discussion that
> mentioned red copper that cautioned that it is hard to disperse (I
> can personally vouch for that now). I just happen to have a couple of
> gallons of really good wetting agent on hand (just part of being an
> involved orchid grower). At least I passed that hurdle.
>
> Marni
>
>
> William Hendry wrote:
> >Yes, bentonite would certainly add to the gelling you already have. And
> >someone else with whom I spoke confirmed (their opinion anyway) that too
> >much sodium silicate would cause flocculation. So maybe that's true with
> >Darvan as well. Do we know what Darvan, a name brand, really is in
chemical
> >terms?
>
> --
>
> Marni Turkel
> Stony Point Ceramic Design
> 2080 Llano Rd 1B
> Santa Rosa, CA 95407
>
> Phone: 707-579-5567
> Fax: 707-579-1116
> http://www.marniturkel.com
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Marni Turkel on sat 3 aug 02
Jeff,
I will indeed pass on what I learn from Vanderbilt. I am trying out
using Darvan 7 as opposed to 811 and will let you know how that goes.
It may not be right away as I am near melt down getting ready to
leave on Tuesday for the New York Gift Show.
Marni
--
Marni Turkel
Stony Point Ceramic Design
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone: 707-579-5567
Fax: 707-579-1116
http://www.marniturkel.com
Jeff Longtin on sat 3 aug 02
Hey Marni,
Do indeed share any info you garner from the Vanderbilt guys, if you would?
Years ago I spoke to them about my porcelain slip deflocculation problem and
found their advice to be right on the money. As this glaze flocculation
problem is one we all cross at some point maybe they can shed some light as
too a possible solution.
Thanks!
Take care
Jeff Longtin
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