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terra sig

updated fri 28 sep 07

 

Jay Landis on tue 20 aug 96

I followed the discussion on 'terra sig" with intrest. I have two questions:
1- Where does one buy Tetrasodium Pyrophosphate,and how much do you use?

2-What is the best way to burnish the "terre sig",with a soft cloth,plasticor
a soft brush?

Jay Landis ,in cool Pinewood ,Arizona

Vince Pitelka on tue 20 aug 96

At 05:26 PM 8/20/96 -0400, you wrote:
>----------------------------Original message----------------------------
>2-What is the best way to burnish the "terre sig",with a soft cloth,plasticor
>a soft brush?
>Jay Landis ,in cool Pinewood ,Arizona

Sorry to harp on terminology again, but you are not burnishing the terra sig
unless you rub it with a polished stone or some other hard shiny tool.
Terra sig does make a very good burnishing slip, but normally we just polish
terra sig. The best material for polishing the terra sig that I have found
is old well-worn flannel, or a very old cloth diaper or tee-shirt. Cut the
pieces out so that you eliminate all seams, pockets, etc. Watch out
especially for BUTTONS!. You can also get good results with a VERY soft
brush, such as we used to use for polishing shoes back in the days when we
polished shoes. It is important to polish the terra sig IMMEDIATELY after
the surface moisture is absorbed but before it starts to dry completely. On
bone-dry ware, especially if it has been sanded, I like to apply a series of
layers of VERY THIN terra sig (with no polishing between layers) to
introduce adequate moisture before polishing.

- Vince

Vince Pitelka - vpitelka@Dekalb.Net
Phone - home 615/597-5376, work 615/597-6801
Appalachian Center for Crafts, Smithville TN 37166

Bob Kavanagh on mon 23 sep 96

There are several articles on terra sig in the most recent issue
(septembre/octobre 1996, #90) of "la revue de la ceramique et du verre" 61
rue Marconi BP 3, 62880 Vendin-le-Vieil, France . The articles touch on
history, technique, innovations, etc. As you might expect, it's in French.

bob kavanagh, hudson (60 kilometers west of Montreal

Vince Pitelka on thu 12 dec 96

Gary Wagoner at Auburn University kindly emailed me that lost post on terra
sig which I sent to the list six months ago. Here it is in its entirety,
but I have modified it a bit and added a few things.

I received a number of inquiries about my reference to "super-refined terra sig
which gives a high luster in a single coat with a single polishing." Let me
ammend that by saying that you can get a high luster with a single coat, but
you will not get opacity. If you want to conceal another clay beneath, it
will take multiple coats, but make sure they are mixed and applied as
described below.

Here's the scoop. I expect that my approach is very similar to that of
others who go for a highly-refined terra sig. Too many of the recipes out
there do not
separate out the large particles adequately, and the product is not a true
terra sig. I started researching this when I began doing my "ancient clay"
classes and workshops at U-Mass about ten years ago. First experiments were
from the standard recipes in books and CM, and the results were unsatisfactory.
I wanted what I had seen on ancient Greek and Roman pots. Finally, via
Parmalee, I discovered the work of a German ceramic chemist named Schumann,
who researched terra sigs and discovered the real secrets, which had been
lost for about 1600 years. Schumann's info guided me to the current system
I use.

I usually use redart, ball clay, or goldart as a starting point. I start
with a small
amount of hot water, and into it I dissolve the deflocculant - .25% (1/4 of
1%) soda ash AND .25% sodium silicate (it seems to work better than either
one by itself), based on the dry weight of the clay I am going to make into
terra sig. I add this to some cold water, then add the clay, and add more
water, blending with a jiffy-mixer, until the mixture is very thin, checking
with the hydrometer until the reading is 1.2 for the redart slip or 1.15 for
the ball clay slip. I place the bucket with this mixture up on a table (for
reasons which will become evident) and leave it undisturbed for exactly 20
hours. After the 20 hours I siphon off the uppermost, thinnest liquid with
a winemakers siphon - this tool is ideal for the task, because it
has a length of flexible clear plastic hose connected to a stiff clear
plastic length about 20" long, with a small "cap" on the end so that the tip
of the siphon sucks from above rather than below. This makes it much easier
to tell when you begin to get to thicker material, which is absolutely critical.

The 20-hour settling time may seem arbitrary, but it's not. There are several
forces at work in this deflocculated mix. The deflocculant introduces same
electrical charges to the clay particles, causing them to repel one another
and stay in suspension longer. Also, there is the ever-present atomic
vibration which
causes particles in liquids to naturally disperse. Working against these
forces is gravity, causing particles to settle out. At 20 hours, gravity
has caused all the heavier particles to settle out, while the finest
particles are still in suspension, due to atomic vibration and deflocculation.

I start the siphon with the tip just barely immersed in the settled mix. DO
NOT AGITATE THIS CONTAINER OR THE SETTLED MIX AT ALL. As mentioned above,
place it up on a table BEFORE the 20-hour settling period. I slowly feed
the tip of the siphon down into the mix as the thin liquid is siphoned off.
I keep
the tip so close to the surface that it periodically will suck a small
amount of air. If it sucks too much the siphoning action will stop, but
having it suck a little bit of air is critical, because it gives a good
indication of how thick the liquid is. As soon as you get to thicker liquid
the siphon will begin to suck much more air. As soon as this hapens, STOP
SIPHONING. Resist the temptation to keep siphoning, because the product
will be inferior. I have never tried to do anything with what remains in
the bucket, which is MOST of what I started out with.

You can siphon into any container, and the siphoned liquid will of course be
far thinner than the original specific gravity, and will be unuseable, so
the question then is how to concentrate it. I am the proud owner of a
36"-diameter restaurant wok, which I bought at a flea market for one buck.
Using this as a slump-mold, I made 24"-diameter terracotta evaporating
dishes with a raised 2" edge. I place one of these on a chair and siphon
the terra sig directly into it. The water soaks into the terracotta (any
bisque-fired claybody would work) and evaporates from the back and from the
rim. It takes about a week for the terra sig to get back to a useable
specific gravity (dependent on temperature, humidity, and air movement).
Don't cover the evaporating dish. Anything that settles into it out of the
air won't do it any harm. Don't worry if it seems to be solidifying around
the edges. When it has thickened considerably, scrape the solidified stuff
loose with a clean rubber scraper, and agitate the mix with a whisk. If
necessary, work the lumps against the bottom of the dish with a very clean
sponge to bring all the terra sig back into suspension. Decant some into a
tall container and check the s.g. If it is still thin let it evaporate some
more. If it is thicker put it in an appropriate container and
add water.

I originally started using the resulting product at a specific gravity of
1.2 or even higher, but ran into trouble with it peeling and chipping. Now
I thin it to 1.13 to 1.18, depending on the results I want. When I said I
use one coat that was a bit misleading. I apply to bone dry clay, often
sanded. I use a wide soft brush, and I simply brush on repeated flowing
strokes until I get an opaque buildup (still extremely thin). As soon as
the surface liquid has soaked in, I polish with a soft piece of flannel or
T-shirt material. Remove all buttons and seams before using the cloth to
polish. I usually get a glassy shine in one polish. It's magical. The
amount of terra sig I brush on depends on how opaque I want the coat to be,
and how much I want it to smooth out the texture of the clay. It is
possible to get a very high shine with an almost transparent coat, because
the shine results from the clay platelates laying flat on the surface, and
in this refined terra sig the
particles are so fine that a distribution of them over the surface will give
a good shine and yet still allow the clay beneath to show through. A good
terra sig may be the world's most perfect substance.

Expect to use a LOT OF CLAY to get a good terra sig, but the results will be
worth it. To get a gallon of redart terra sig takes about 75 pounds of
redart clay. Goldart gives about the same yield, while ball clay gives a
higher yield, since it is finer to begin with. As I mentioned above, I have
never tried to do anything with the deflocculated residue left from the
settling process. It would be good for making thick slip. If you add it to
a claybody you would be deflocculating the clay, which will reduce plasticity.

I have fired all my terra sigs to a maximum of ^02. I have applied very
thin coats to bisqueware and fired them with adequate results, but never as
good a shine or as durable a surface as when applied to bone dry. Terra sig
applied to leather hard tends to loose it's shine when it dries. At ^04 the
redart sig gives a bright brick-red-orange color, the goldart gives an
off-white, and the ball clay gives a PURE white. The redart sig, when
properly made, is denser, and in a blackware bonfire gives beautiful
brown-to-black colors. The ball clay sig in the blackware firing or in raku
post-firing smoking gives intense jet-black.

Recently, some of my students who are using very gritty clays in high fire
have tried coating the feet of their wares, and occasionally the contact
surface between jar and lid with terra sig, to give a smoother surface than
the base clay. Personally, I like the base clay showing in these areas, but
it is a matter of personal taste. As Louis Katz indicated to me, goldart
sigs do retain a bit of shine in high-fire, but nothing like low-temp
polished terra sig. Ball clay sigs in high fire simply give a white satin
finish - not really a shine at all. Of course, a redart sig would turn to a
glaze, but more refractory clays might give great results. Kaolins and fire
clays give extremely low yield in terra sig, because of the coarseness of
the particle size. Stoneware clays give better results, depending on the
fraction of fine particles. Experiment away.

I always like to work with pure clay terra sigs, because they give the best
shine. It is of course natural that others will want more color, but unless
you can ball-mill the mixture the shine will be reduced. At U-Mass we
experimented with both oxides and mason stains and got good results by
ball-milling the thickened evaporated terra sig and colorants for a day or so.

Good luck, email me any questions, and please let me know of your results,
either on Clayart or via email.
- Vince

Vince Pitelka - vpitelka@Dekalb.Net
Phone - home 615/597-5376, work 615/597-6801
Appalachian Center for Crafts, Smithville TN 37166

R Wuetherick on thu 23 jan 97

Hi all,
Some were asking about that "GUN METAL" finish with
terra sig. Well I don't know how to do it but thanks to
Elke Bodgett giving me the name of Pierre Bayle I
know where to look. If you have ever saw one of his
terra sig pieces you would be amazed!

Which leads me to this question. Does anyone
know of any of his pieces being on-line?

Once again thanks to Elke there is an excellent
article about this in the greek magazine
"Kerameiki Techni" apparently this article
discusses the process in it's entirty.

I am going to try and "PRY" the magazine
from Elke and will maybe be able to tell you
more. Though I don't know if I will have a
chance on getting it unless she wants to
give it toi me.. She is pretty tough ;-)

Cheers,
Rod Wuetherick

barbara@aoi.ultranet.com on wed 26 feb 97


Bill,

Terra sig is usually applied to the unfired piece, bisques *no higher*
than ^012 and if refired, then ^010 maximum. Take a look at the current
issue of CM and note that the clay itself makes a perfect terra sig.
No need to mix, deflocculate, decant, etc. As long as your clay is
without heavy grog, you can actually create the terra sig on the surface
of the pot.

Disclaimer: There are a thousand recipes for the perfect terra sig.
I've related my own favorite, but I also enjoy Bob Green's (Vermont potter)
simple deflocculated recipe that requires only a cloth for burnishing. Much
like Vince Pitelka, just less work and exactness in the mixing.

Moral: Try as many different techniques and recipes as you can stand and
settle on the ones that work best for you.

Dinah Collopy on fri 1 aug 97

About 11/2 yrs ago I made a BIG BUNCH of terra sig and put it in 1gal. glass
bottles.
I used some at the time I made it (it worked well) and when I went to use
some today it was like pudding. Can it be "reconstituted" by just adding
water? Do I add a fair amount of water and let it settle again and syphon
from the middle as I did originally?
Can I just add a little water and mix it with a graze mixer since supposedly
what's in there are just the fine particles? Thanks for any suggestions.
Dinah in AZ where its not very "lovely"--HOT, HOT

Roeder on sat 2 aug 97

Hi there,

Just add water. No problem. In fact, Vince Pitelka ,Sig King of the
list, recently wrote me that he dried it out completely, shipping it to
the west coast where it will be reconstituted for his workshop there.

Candice Roeder

>
> ----------------------------Original message----------------------------
> About 11/2 yrs ago I made a BIG BUNCH of terra sig and put it in 1gal. glass
> bottles.
> I used some at the time I made it (it worked well) and when I went to use
> some today it was like pudding. Can it be "reconstituted" by just adding
> water? Do I add a fair amount of water and let it settle again and syphon
> from the middle as I did originally?
> Can I just add a little water and mix it with a graze mixer since supposedly
> what's in there are just the fine particles? Thanks for any suggestions.
> Dinah in AZ where its not very "lovely"--HOT, HOT

Louis Katz on sat 2 aug 97

If your Sig was already separated you can just add water, but I would use
distilled water. If it was not settled before you can use distilled water
and decant, but consitent technique is really needed if you want
consistent results.
Louis

Louis Katz
Texas A&M University Corpus Campus
lkatz@falcon.tamucc.edu
http://www.tamucc.edu/~lkatz

Shannon Hayes on sun 26 jul 98

Okay...I have tried for a long time to get a good terra sig on my pots. I
want something similar to what Rick Hirsh is doing. I am using mason stains
in the sig and putting it over a white clay body. It just does not cover.
Does anybody know what Im doing wrong. Thanks.

Shannon
STILL hot in Texas!!!!

Gary Huddleston on mon 27 jul 98

Try contacting Marty Ray at Northlake College in Irving for a fairly good=
terra sig formula, and then ask Angel at Trinity Ceramics aboaut how to =
produce various colors in terra sigs. Marty is the Director of art and =
oversees ceramics, will be at the school most days and returns phone cal=
s and email although I don't have either # at this time because the scool=
is only about 2 miles from my house, so I drop in whenever...
Angel is the most helpful sales/service person I have ever met. Her knowl=
edge of clays and chemicals is excellent, but from experience, I do not =
believe a stain works on a terra sig, because the color comes from differ=
ent kinds of chemicals than those used in stains. I could be wrong, that=
is why I suggest these two fine women artists.

----------
>
>

FRANK GAYDOS on mon 27 jul 98

FRANK GAYDOS wrote:
>
> Shannon Hayes wrote:
> >
> > Okay...I have tried for a long time to get a good terra sig on my pots.
> > Does anybody know what Im doing wrong. Thanks
>
> Shannon,
> I think we need to know what you ARE doing first in order to suggest
> ways to improve.

> I just took a class with Woody Hughes and he is a Terra Sig master.
> Here is what he suggests;
> Use ball clay
> Ball Mill for about 8 hours
> Add real Calgon , not the stuff you get in the store. You need water
> softener AKA Sodium hexametaphosphate.
> Add colors to base TSig.
> Use soft cotton or cleaners plastic, my favorite, to polish, on about
> three or four coats of TSig.
> Apply to Bone dry or bisque, I have done both with good results.
> Dont use a groggy body, it will not polish well.
>
>
> Good Luck,
> Frank
>
> --
> Frank Gaydos
> 510 Gerritt St.
> Philadelphia,Pa.19147-5821 USA
> fgaydos@erols.com

--
Frank Gaydos
510 Gerritt St.
Philadelphia,Pa.19147-5821 USA
fgaydos@erols.com

Russel Fouts on tue 28 jul 98

Shannon,

>> Okay...I have tried for a long time to get a good terra sig on my pots.
I want something similar to what Rick Hirsh is doing. I am using mason
stains in the sig and putting it over a white clay body. It just does not
cover. Does anybody know what Im doing wrong. <<

I thought Rick Hirsh was doing bronze? ;-)


1. How are you making the sig?
2. How many coats are you using?
3. Check that the density (sometimes called specific gravity) is between
1.12 and 1.15. Actually mine is less than this and still covers in 4 coats.
You might want to thicken it by evaporating some of the water out.
4. Read Vince Pitelka's piece on Terra sig on terra sig (I think it's on the
Clay Web.) It's a lot more than I want to do to make sig but it people say
it makes really great sig.
5. Are you applying it to bisque or raw clay and if raw, when?

To you "glaze gellers" out there (Pete Pinnell's column in Clay times). I
tested using Magnesium Sulphate (Epson Salts) to "gel" my sig so it would
apply thicker. It now covers in one coat but I prefer two. Has anybody else
tried this with a sig? It doesn't "gel" much, only gets a little thicker. I
think, because of the high amount of water compared to clay.

I think the only risks might be that the thicker sig won't stick or that the
magnesium might scum on the white body. I haven't fired the test yet, so
I'll let you know.

By the way, Pete's right about being cautious about adding dry epsom salts a
slop. I experimented with my sig waste (still trying to do something with
that stuff). Normally it settles out like cement at the bottom of the pail.
I mixed it all up again with the aid of a drill mixer and added 8 tsps of
dry crystals to about 10 litres of the slop. "Bucket of Wax"! Thanks Pete!

But I think I can finally put that waste to use.

Russel

Russel Fouts
Mes Potes & Mes Pots
Brussels, Belgium
32 2 223 02 75
Http://users.skynet.be/russel.fouts
Http://www.japan-net.or.jp/~iwcat

PLEASE SEND ALL REPLIES PUBLICLY

Vince Pitelka on thu 21 jan 99

I received the following post privately, and attempted to respond, but it
bounced back to me repeatedly. Hopefully Carol Donner will get my response
via Clayart.

At 10:11 AM 1/20/99 -0700, you wrote:
>Hi, I just read your very informed piece on burnishing in ClayArt. I
>have a question that I cannot find an answer to. If you use terra sig
>on a white stoneware piece, do you burnish the stoneware first? Or do
>you apply the terra sig to it and lightly polish? Or do you burnish
>terra sig at all? I would really love to hear from you on this. I am
>a sculptor, trying to get good results pit firing my pieces. Hope to
>here from you, you seem to have the experience. Thank you, Carol
>Donner, Tucson

Carol -
You do not want to burnish before applying terra sig, because you leave a
surface that slip cannot stick to, leading to possible peeling and flaking
of the sig surface. Many people burnish leather-hard clay, but personally, I
like to let the piece get bone dry, sand it lightly, and then paint on
repeated flowing coats of terra sig, letting it soak in betwen layers. The
introduced moisture is adequate for burnishing on a small piece. Terra sig
burnishes beautifully. Or of course you can simply polish it with a soft
cloth or a piece of grocery-store-bag plastic stretched over your fingertip.
For the very best shine, burnish well, and then as a final step use the
plastic-covered fingertip. For larger pieces, the introduced moisture from
the terra sig is not enough for burnishing. In that case it is adviseable
to apply the terra sig to your satisfaction, and then a very light smear
coat of lard, crisco, or vegetable oil. Then burnish, but don't be
surprised when it initially seems like you are just smearing things around.
In reality you are leveling and consolidating the surface, and pretty soon
the shine will start to emerge. The plastic over the fingertip works even
better on the surface which has been greased, and I find that the greased
surface gives a more durable burnish on the dry greenware, when it is
otherwise such a fragile surface.
Good luck -
- Vince


Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166

MR WENDELL R RIDENOUR on mon 25 jan 99

Do you have a
rec. for Terra Sig, using tobacco juice? Ellen

Lili Krakowski on wed 27 jan 99

I know nothing about terra sig, really BUT, HELLO THERE, TOBACCO JUICE IF
POISONOUS. IF YOU DON'T BELIEVE ME READ A BOOK ON TOXICOLOGY, CHECK OUT
YOUR LOCAL POISON CONTROL CENTER. Whatever. I am sure it is as
dangerous in terra sig as in colorant used for mocha ware. For the
latter strong vinegar is perfectly swell. How will you get to be a
crotchety old person, if you don't take care of yourself while young?
Answer me that one!
Lili Krakowski

martin howard on thu 3 feb 00

Just read Vince's wonderful method of preparing Terra Sig. Thanks friend.

To help those of us outside the USA, would someone post up what Redart and
Goldart clays consist of?
I would assume the first to be a medium throwing red clay, like our Standard
Red in GB, from Valentine Clays, a mixture of Keuper Marls.

The Terra Sig process is trying to get at the finest particles and then
polish them. The finest clay is surely bentonite, montmorrillonite, fullers
earth, cat
litter (even though strictly speaking it is not really a clay). So, Vince,
what kind of alteration to your program for creating terra sig would you
recommend if you were starting with dried bentonite?
I have a large quantity of it very slowing drying in the kiln room and
showing
lovely grand canyon cracks.

An earlier terra sig from cat litter came out less smooth than I expected
and was difficult to burnish, but I would like to continue down that path of
exploration, perhaps mixed with other clays so as to get other colours. That
might lead to once fired ware, if it caught on in this neck of the woods,
using perhaps a vitreous slip on the inside and a terra sig outside. They
are really very similar.

Martin Howard
Webb's Cottage Pottery
Woolpits Road
Great Saling
BRAINTREE
Essex CM7 5DZ
01371 850 423
martin@webbscottage.co.uk
www.webbscottage.co.uk Should be ready for 2000 :-) or 2001

Vince Pitelka on fri 4 feb 00

>Just read Vince's wonderful method of preparing Terra Sig. Thanks friend.
>To help those of us outside the USA, would someone post up what Redart and
>Goldart clays consist of?

Martin -
Redart is just a processed, air-floated red earthenware clay. Goldart is a
processed air-floated stoneware clay. Just use whatever you requivalent is.
As I stated in the article, yield will differ greatly from one clay to the next.

>litter (even though strictly speaking it is not really a clay). So, Vince,
>what kind of alteration to your program for creating terra sig would you
>recommend if you were starting with dried bentonite?

The problem with making terra sig from Bentonite is getting the fine
particles to separate out. But wait! They're all fine particles!! No,
that's not true. The average size is quite fine, but with so many fine
particles it will not separate into layers in the settling container the way
a coarser clay will. This is a problem with ball clay, but I have had good
luck just siphoning off the top 2/3 or so from the settling container. You
never do really run into a thicker layer with a distinct separation, the way
you do with redart. Redart yields the best terra sig I have ever used. My
theory is that there is a broad spectrum of particle sizes, and the coarse
and medium-size ones easily settle out, leaving only the finest ones in
suspension. And I would wager that those finest particles are as fine as
anything you would encounter in a Bentonite. If you could get a bentonite
to separate, the yield would be very high. To make a sig from Bentonite, I
would be tempted to just deflocculate it, thin it to the desired specific
gravity, and just go ahead and use it without the settling process. Let me
know what happens..
Good luck -
- Vince

Vince Pitelka
Home - vpitelka@DeKalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166

vince pitelka on sun 4 feb 01


> No doubt Vince will correct me if I am wrong here...
> Deflocculants do not "settle out the slip".
> The purpose of a deflocculant is to keep the clay
> particles from "flocking", allowing them to stay in
> suspension. The amount of deflocculant does matter. Too
> much and more than the finest particles will stay in
> suspension, giving a less fine top layer. Too little and
> more will settle than desired. Just right is, well, just
> right.

Judy -
The only thing that is a little misleading here is that more deflocculant
will not cause more particles to stay in suspension. Once the sig is
deflocculated it does not become more deflocculated. Once the particles
have same electrical charges and are repelling each other the job has been
done. The problem is that additional deflocculant will begin to flux the
sig in the firing. Too little deflocculant, and all the particles settle
out. In any suspension you have three forces working - you have gravity
dragging the particles downwards, you have atomic vibration causing the
particles to bounce off one another and stay in suspension, and you have the
electrical charge of the particles. Opposite charges cause the particles to
attract or "flock" together, overpowering the other forces, and the
particles settle out. When the suspension is deflocculated, the resulting
electrical repulsion between particles, plus the forces of atomic vibration
are enough to keep the finest particles in suspension, while all the coarser
ones settle out. That's it in a nutshell.

One the suspension is deflocculated, any additional deflocculant can start
to flux the mix, and can cause the sig to shrink in the firing, which will
likely cause it to chip and flake.
Best wishes -
- Vince

Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/

j e motzkin on sun 4 feb 01


Paul Taylor wrote:
..>any amount of defloculant and grinding will give you
more
fine terrasig for the
> amount of clay, any amount of defloculant, after a
certain point, will
> settle out the slip into layers the top layer will make

as good a terrasig

This is a confusing way to see the making of TS.
No doubt Vince will correct me if I am wrong here...
Deflocculants do not "settle out the slip".
The purpose of a deflocculant is to keep the clay
particles from "flocking", allowing them to stay in
suspension. The amount of deflocculant does matter. Too
much and more than the finest particles will stay in
suspension, giving a less fine top layer. Too little and
more will settle than desired. Just right is, well, just
right.
A basic recipe...1 liter of water, 400 gr. of clay, 4gr
soda ash.
Judy


=====


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Anita M. Swan on mon 5 mar 01


I teach middle school and we do a pitfiring each year. I use Vince
Pitelka's directions for terra sig - specific gravity, the whole nine
yards (great tie-in to the science curriculum) but we don't mix our own
clay, so have no use for the "leftovers." Its killing me to throw this
stuff away! Any suggestions? Anita

vince pitelka on mon 5 mar 01


> I teach middle school and we do a pitfiring each year. I use Vince
> Pitelka's directions for terra sig - specific gravity, the whole nine
> yards (great tie-in to the science curriculum) but we don't mix our own
> clay, so have no use for the "leftovers." Its killing me to throw this
> stuff away! Any suggestions? Anita

Anita -
Clay is cheap, and what's left after you make terra sig has had all the good
fine particles removed from it. It just isn't good for much. You have
extracted the "ceramic elixir of the gods" from the raw clay, and you can
throw away the dregs with a clear conscience.
Best wishes -
- Vince

Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/

bob kravis on sun 13 jan 02


hi. i'm looking for a good terra sig recipe. thanks. maxine

vince pitelka on sun 13 jan 02


Maxine wrote:
"hi. i'm looking for a good terra sig recipe"

Maxine -
Check out my article about terra sig at Tony Hansen's Digitalfire website at
www.digitalfire.com/education/glaze/terasig.htm

There are easier terra sig recipes, but they generally give inferior
results. It is worth the trouble to do it the long way.
Best wishes -
- Vince

Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/

Roger Korn on mon 14 jan 02


My wife, Kayo, went to Vince's workshop up at Michael McDowell's a few years back
and brought back the terra sig notes. I made a glaze hydrometer out of a stick and
some lead shot. Followed the sacred recipe to the letter. Success! First try! Since
then, the scraps of any new clay (we dig lots of holes when we travel) get tested,
using the Sacred Ritual, and we get all kinds of interesting and wonderful results.

Take a look at page 102 of Vince's Clay: A Studio Handbook for a very clear
description of the burnishing process. The terra sig procedure is found there too,
but Vince probably didn't want to mention it - he's so modest .

Hope this helps,

Roger

vince pitelka wrote:

> Maxine wrote:
> "hi. i'm looking for a good terra sig recipe"
>
> Maxine -
> Check out my article about terra sig at Tony Hansen's Digitalfire website at
> www.digitalfire.com/education/glaze/terasig.htm
>
> There are easier terra sig recipes, but they generally give inferior
> results. It is worth the trouble to do it the long way.
> Best wishes -
> - Vince
>
> Vince Pitelka
> Appalachian Center for Crafts
> Tennessee Technological University
> 1560 Craft Center Drive, Smithville TN 37166
> Home - vpitelka@dtccom.net
> 615/597-5376
> Work - wpitelka@tntech.edu
> 615/597-6801 ext. 111, fax 615/597-6803
> http://www.craftcenter.tntech.edu/
>
> ______________________________________________________________________________
> 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.

--
Roger Korn
McKay Creek Ceramics
In AZ: PO Box 463
4215 Culpepper Ranch Rd
Rimrock, AZ 86335
928-567-5699 <-
In OR: PO Box 436
31330 NW Pacific Ave.
North Plains, OR 97133
503-647-5464

jim or karen on thu 21 aug 03


Hello!

I'm new to pottery and have been told that my sculptures would look good =
if I used terra sig on them ( I plan to fire to cone 6). The problem I =
have is that my sculptures are dry and everything I've read says to =
apply terra sig to leatherhard clay. Are there any recipes for terra =
sig for dry clay?

I'd appreciate your help.

Karen

Snail Scott on thu 21 aug 03


At 06:39 AM 8/21/03 -0700, you wrote:
...have been told that my sculptures would look good if I used terra sig on
them ( I plan to fire to cone 6). The problem I have is that my sculptures
are dry and everything I've read says to apply terra sig to leatherhard
clay. Are there any recipes for terra sig for dry clay?



Don't bother with terra sig at ^6. It's best at ^012-^010.
At ^6, it looks pretty much like any other slip. No shine.
If your piece needs the strength of being fired to maturity,
(^6) I'd avoid the terra sig for now. Save it for a piece
made of earthenware, which will be stronger when fired to
low temperatures.

As for dry clay, it can be done, better on some clay bodies
than others. But, keep it thin, and make sure the underlying
clay is pretty smooth to start or you'll just burnish up
the bumps.

-Snail

Vince Pitelka on thu 21 aug 03


Karen wrote:
"I'm new to pottery and have been told that my sculptures would look good if
I used terra sig on them ( I plan to fire to cone 6). The problem I have is
that my sculptures are dry and everything I've read says to apply terra sig
to leatherhard clay. Are there any recipes for terra sig for dry clay?"

Karen -
On the contrary, any properly prepared terra sig is far better applied to
bone-dry ware. If applied to leather hard ware, it will loose it's shine as
it dries. You can find out about my terra sig recipe at the Digitalfire
site at http://www.digitalfire.ab.ca/cermat/education/132.php
Good luck -
- Vince

Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/

Russel Fouts on fri 22 aug 03


Karen,

>> I'm new to pottery and have been told that my sculptures would look good if I used terra sig on them ( I plan to fire to cone 6). The problem I have is that my sculptures are dry and everything I've read says to apply terra sig to leatherhard clay. Are there any recipes for terra sig for dry clay? I'd appreciate your help. <<

You can apply sig at any stage, it all depends. I apply it to bisque or
bone dry, anyone's milage may vary. Make some up and try it.

My primer should get you started:

http://users.skynet.be/russel.fouts/Files/Terra-Sig%20Primer.txt

Russel

--
Russel Fouts
Mes Potes & Mes Pots
Brussels, Belgium
Tel: +32 2 223 02 75
Mobile: +32 476 55 38 75

Http://www.mypots.com
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Entry Department on thu 14 oct 04


This may be a very dumb question, but I am going to ask anyway!
I have been following the string on terra sig and am fascinated by the =
finish. =20
Can you make a pot using terra sigillata slip and have it vitrified so =
that it will not leak, i.e. for functional ware?=20
My book, Ceramics by Glenn Nelson tells me that it scratches easily and =
it is not completely waterproof. =20

Thanks for helping a newbie!

Vince Pitelka on thu 14 oct 04


Just for future reference, it is simple courtesy to alwasy sign an email
message with a name, and more so when you send someone a message asking for
help.

If you fire above low-fire temperatures, you will loose the shine, and the
terra sig will become something else. It is only a low-fire process. Yes,
it does scratch easily, but when applied, polished, and fired properly, it
is quite waterproof. Ironically, the true terra sig process was lost
through the Middle Ages and into the modern era, and was only rediscovered
in the late 1800s by a German ceramic chemist looking for a waterproof
coating for clay sewer pipe. Pretty romantic, eh?
Good luck -
- Vince

----- Original Message -----
From: "Entry Department"
To:
Sent: Thursday, October 14, 2004 12:45 PM
Subject: terra sig


This may be a very dumb question, but I am going to ask anyway!
I have been following the string on terra sig and am fascinated by the
finish.
Can you make a pot using terra sigillata slip and have it vitrified so that
it will not leak, i.e. for functional ware?
My book, Ceramics by Glenn Nelson tells me that it scratches easily and it
is not completely waterproof.

Thanks for helping a newbie!

______________________________________________________________________________
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.

Rod Wuetherick on thu 14 oct 04


"Pretty romantic, eh?"

Vince are you practicing fitting in up here in Canada? eh?

Peace,
Rod

Allyson May on sat 26 mar 05


Vince has the recipe for a "superior" form of terra sig and I am sure =
this is in the archives. I have stored terra sig for more than a year =
and it does just fine. As someone else stated, you must shake the stuff =
every so often or it hard pans in the bottom of the jars like =
crazy!!!!!! Terra sig is available commercially (Clay Art Center, =
Seattle) as well as others. It is expensive and I believe of inferior =
quality. An easy Sig recipe belong to Charlie Riggs and is as follows: =
1. 3 gallons of water in a clear container, 2. Add 1 tsp of soda ash or =
sodium silicate, 3. Stir in 15 lbs of ball clay or XX saggar, 4. Set the =
bucket up on a counter or table, 5. Wait one day, 6. Siphon off the =
top 1 1/2 gallons and discard the rest. This sig may be dipped, =
brushed, or poured The best method however, is spraying. Alternate =
spraying coats and buffing until the desired shine is achieved. Don't =
touch the polished sig with your bare hands as it may leave permanent =
marks. Do not fire above ^08 or you will lose your sheen.
Hope this helps.
Allyson May
Stoney Creek Pottery
Bloomington, IN
AMay4@msn.com

Rogier Donker on sat 15 jul 06


Hi!
You might want to read the Terra Sig story on my web site (Scroll
down a little on the Pottery page). If you find yourself intrigued...
let me know ...I have a few pounds of the original Turkish stuff left...
Rogier
See us on the web at http://www.donkerstudio.org

Wes Rolley on thu 27 sep 07


I have been frequenting some science blogs this summer and, much to my
surprise, I found on that is named Terra Sigillata. Quite a different
take on the meaning of "sealed earth." http://scienceblogs.com/terrasig/

Gotta go ingest some clay.

--
"I find I have a great lot to learn ‚EUR" or unlearn. I seem to know far too much and this knowledge obscures the really significant facts, but I am getting on." -- Charles Rennie Mackintosh

Wesley C. Rolley
17211 Quail Court
Morgan Hill, CA 95037
(408)778-3024
http://www.refpub.com/