vince pitelka on sun 28 jan 01
> I mixed up a batch of grolleg about a month ago to make terra sig, but I
> forgot about it and it has all settled. Is there any way to remix it so I
> can siphon off the good stuff?
Ted -
Yes. When this happens, just use a jiffy mixer to bring everything back up
into suspension, and then let it set the necessary amount of time (I like 20
hours), and then decant off the sig. Don't expect a very high yield from
Grolleg or any other primary kaolin, because the average particle size is so
coarse.
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/
Ted Banton on sun 28 jan 01
I mixed up a batch of grolleg about a month ago to make terra sig, but I
forgot about it and it has all settled. Is there any way to remix it so I
can siphon off the good stuff?
TIA
Ted Banton
Martin Howard on mon 29 jan 01
Yes, just start again where you left off. Give a good stirring and then
leave for the 20 hours that Vince recommends. Don't let the container be
moved, touched or even breathed on during that time.
Then siphon off the top third or less.
The highest part, even though it may look absolutely clear, contains the
finest particles and is therefore the better terra sig.
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
Have you seen http://www.thefriend.org
Download The Friend, the weekly Quaker Newspaper,
3 days before it is published.
That's Quick for Quakers.
Paul Taylor on mon 29 jan 01
Dear Ted
The making of terra sig is a bit overrated as a skill. If you blunge or
better mill any clay mixed with a bit of defloculant you will make a terra
sig. I have the odd feeling that the amount of soda does not matter too much
as long as you put enough in to make the slip alkaline .
Of course There is obviously the optimum amount to get the perfect
controlled sigg, and to many just shoving some defloculant in see if that
works and forgetting to write down the amounts will not do.
In a fit of the obsessives I asked a chemist to send me a formula for
stokes law , to get the particle size I deserved . I took one look at the
formula and went back happily to bunging a bit of soda in a bucket, mixing
up the slop and poring it in a glass sweet jar. When I have decided by the
look of it that it has settled down enough I decant off the layer of the
material I want .
So either I am terribly lucky or you to can just mix up the stuff again
with water adding a splash of sodium silicate for luck.
or better still if the stuff has settled out, because you forgot to
decant it, let the slop dry out and carve the very top layer off the lump
and soak that down to use. Remember as always a little grinding goes a long
way so you could put the terra sig in a little jar mill or at worst a pestle
and mortar then a fine sieve.
With a careful look at the layers when you separate them you may do as
well as if you had labored with Stoke - again try to take a note.
Regards from Paul Taylor
http://www.anu.ie/westportpottery
There are two sides to an argument - ignorance and self interest.
> From: Ted Banton
> Reply-To: Ceramic Arts Discussion List
> Date: Sun, 28 Jan 2001 10:02:25 EST
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Terra sig forgotten
>
> I mixed up a batch of grolleg about a month ago to make terra sig, but I
> forgot about it and it has all settled. Is there any way to remix it so I
> can siphon off the good stuff?
>
>
> TIA
>
> Ted Banton
vince pitelka on mon 29 jan 01
> Yes, just start again where you left off. Give a good stirring and then
> leave for the 20 hours that Vince recommends. Don't let the container be
> moved, touched or even breathed on during that time.
> Then siphon off the top third or less.
> The highest part, even though it may look absolutely clear, contains the
> finest particles and is therefore the better terra sig.
Martin -
Sorry to seem picky. It is not that it is the better terra sig. It is just
that it does contain a fraction of superfine particles, and it is a shame to
loose those, since the whole point of the process is to isolate the finest
platelets. For that reason I never ever decant and discard any clear
liquid. I simply start siphoning from the top, and keep going through the
clear layer (if there is one) and continue until I first encounter thicker
sediments. It gives a much thinner product, which must be concentrated by
evaporation, but it is well worth the extra trouble.
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/
vince pitelka on mon 29 jan 01
> The making of terra sig is a bit overrated as a skill. If you blunge
or
> better mill any clay mixed with a bit of defloculant you will make a terra
> sig. I have the odd feeling that the amount of soda does not matter too
much
> as long as you put enough in to make the slip alkaline .
This is a little odd. It really is not much trouble at all to get a
superior superfine terra sig. You just have to get a few tools and then
follow the directions. The product will be superior to any sig made as
specified above, unless you just happen to be lucky enough to add the
optimum amounts of water and deflocculant by chance, which is a strange way
to treat your work. Why not just pay $20 for a hydrometer and do it right?
So, the making of superior terra sig is not at all overrated as a skill,
because it does not take any skill to speak of at all. You just need to be
able to follow simple directions.
http://digitalfire.com/education/glaze/terasig.htm
> Remember as always a little grinding goes a long
> way so you could put the terra sig in a little jar mill or at worst a
pestle
> and mortar then a fine sieve.
When you make it properly, you do not have to ball mill it or use a mortar
and pestle.
> or better still if the stuff has settled out, because you forgot to
> decant it, let the slop dry out and carve the very top layer off the lump
> and soak that down to use. Remember as always a little grinding goes a
long
> way so you could put the terra sig in a little jar mill or at worst a
pestle
> and mortar then a fine sieve.
Have you done this? In my experience this does not work. There is no way
to successfuly distinguish between the layers in the dried mass, and
besides, talk about doing it the hard 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/
Paul Taylor on fri 2 feb 01
Dear Vince
If I was a little gung ho in my reply to Ted I am sorry . My only excuse
is that I feel confidence is more important in making pots than measurement
but that does not mean that one excludes the other. And if I think about it
accurate measurement does give confidence - as long as the instructions are
clear uncomplicated and necessary.
Yes mesurment does make a more efficient terrasig but the context of the
question was that of rescuing a terrasig that may have gone beyond
mesurement.
Which in my opinion can be done if needs be; because while the right
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
as any - but not as economicaly as your method.
I have left a bucket of terrasig go completely hard and carved off the
finest layer. It came away from the layers beneath like slate but I did give
the bottom of the top layer a scrape to get the finest of the finest and it
was still possible to distinguish the layers . Ironically the stuff was
too fine for my purposes as I wanted a thick covering with added stains. I
used a plastic bag stretched over a finger to burnish the pots up after
putting on a thick layer of the terra sig.
You do not have to ball mill terra sig but you will get more finer
particle terra sig for the amount of clay.
In the context of the letter I was replying to; if the slop had
completely set hard and you did remove the top layer, grinding it in a
pestle and mortar would get rid of any lumps. Yes! this is the hard way,
but the question was could it be done. layers can be seperated at the dry
stage . Sometimes necessity forces inefficiency on us all. I was just
answering the question that it could be done. I did not expect Ted to take
my suggestion up as a sound methodology but as an all is not lost
suggestion. If you are short of clay and or time .
I suppose I could have advised throw the grelog out and start again I
would throw the least suspect glaze out. Not because of my deep respect for
my work but because of the money I would have lost if it goes wrong.
Regards from Paul Taylor
http://www.anu.ie/westportpottery
There are two sides to an argument - ignorance and self interest.
> From: vince pitelka
> Reply-To: Ceramic Arts Discussion List
> Date: Mon, 29 Jan 2001 23:07:40 -0600
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: Terra sig forgotten
>
>> The making of terra sig is a bit overrated as a skill. If you blunge
> or
>> better mill any clay mixed with a bit of defloculant you will make a terra
>> sig. I have the odd feeling that the amount of soda does not matter too
> much
>> as long as you put enough in to make the slip alkaline .
>
> This is a little odd. It really is not much trouble at all to get a
> superior superfine terra sig. You just have to get a few tools and then
> follow the directions. The product will be superior to any sig made as
> specified above, unless you just happen to be lucky enough to add the
> optimum amounts of water and deflocculant by chance, which is a strange way
> to treat your work. Why not just pay $20 for a hydrometer and do it right?
> So, the making of superior terra sig is not at all overrated as a skill,
> because it does not take any skill to speak of at all. You just need to be
> able to follow simple directions.
> http://digitalfire.com/education/glaze/terasig.htm
>
>> Remember as always a little grinding goes a long
>> way so you could put the terra sig in a little jar mill or at worst a
> pestle
>> and mortar then a fine sieve.
>
> When you make it properly, you do not have to ball mill it or use a mortar
> and pestle.
>
>> or better still if the stuff has settled out, because you forgot to
>> decant it, let the slop dry out and carve the very top layer off the lump
>> and soak that down to use. Remember as always a little grinding goes a
> long
>> way so you could put the terra sig in a little jar mill or at worst a
> pestle
>> and mortar then a fine sieve.
>
> Have you done this? In my experience this does not work. There is no way
> to successfuly distinguish between the layers in the dried mass, and
> besides, talk about doing it the hard 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/
>
Cindy Strnad on sat 3 feb 01
Paul,
It was good of you to write, and I agree that terra sig and burnished slip
are different entities. I'd like to add, though, that a good terra sig is
really and truly very easy to prepare. It takes patience, waiting for all
that water to evaporate away (Okay, I cheated and set it on the kiln in its
bisque bowl to speed things up), but the process itself is neither
time-consuming nor difficult.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
Paul Taylor on sat 3 feb 01
Dear Ted and all
I have received an off post reply from Vince Pitelka .
In it he made some points about terrasig that I had not considered.
I never make replies that are not with in my direct experience but sooner
or later some of my interpretation of direct experience will be inaccurate.
As you can see on my web site I am using what was to myself a terrasig.
After vince's reply I think It was a matter of luck that my slip worked. I
think I stirred Ted wrong and I will have to agree with Vince that a very
superior terrasig can be made by a careful methodology such as his.
Coincidental I have a tinny and beautiful pinch pot given to be by an
American potter (whose name I forget) that has IT'S rim painted with a
perfect terrasig. If I am honest with my self I would have to describe my
terrasig as bernishing slips and this pot's coating as a terrasig. I think
from the difference in quality in the terrasig of the pinch pot and my
bernishing slip is enough to separate the two by those terms.
Vince explained that the amount of defolculant in a terrasig made a lot of
difference to the fired result and he pointed out some faults that I did not
know about caused by too much defloculant in the slop, such as shrinking
cracking and flaking. I have to agree with him. Since I once had one of my
bernishing slips flake off ( I put it down to grease getting onto the pot
from my hand before the pot was painted) I am thinking his methodology may
also apply to my bernishing slips as well. I add stains to the bernishing
slips which I dab on very thickly. I mostly get away with not having a
controlled amount of defloculant because although a bernishing slip has a
finer particle size than an ordinary slip It is not fine enough to be
disturbed by an excess of sodium (defloculant) ; Where as, as Vince pointed
out, a fine terrasig is.
So for my own good I take back what I said and the impression I gave
about terrasig "that they are easy to prepare" and I am looking forward to
using Vince's Research work when making my next batch of forms - for which I
am going to use much weaker color so I can get the finer surface.
Regards from Paul Taylor
http://www.anu.ie/westportpottery
There are two sides to an argument - ignorance and self interest.
> From: Paul Taylor
> Reply-To: Ceramic Arts Discussion List
> Date: Fri, 2 Feb 2001 00:10:15 +0000
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: Terra sig forgotten
>
> Dear Vince
>
> If I was a little gung ho in my reply to Ted I am sorry . My only excuse
> is that I feel confidence is more important in making pots than measurement
> but that does not mean that one excludes the other. And if I think about it
> accurate measurement does give confidence - as long as the instructions are
> clear uncomplicated and necessary.
>
> Yes mesurment does make a more efficient terrasig but the context of the
> question was that of rescuing a terrasig that may have gone beyond
> mesurement.
>
> Which in my opinion can be done if needs be; because while the right
> 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
> as any - but not as economicaly as your method.
>
> I have left a bucket of terrasig go completely hard and carved off the
> finest layer. It came away from the layers beneath like slate but I did give
> the bottom of the top layer a scrape to get the finest of the finest and it
> was still possible to distinguish the layers . Ironically the stuff was
> too fine for my purposes as I wanted a thick covering with added stains. I
> used a plastic bag stretched over a finger to burnish the pots up after
> putting on a thick layer of the terra sig.
>
> You do not have to ball mill terra sig but you will get more finer
> particle terra sig for the amount of clay.
>
> In the context of the letter I was replying to; if the slop had
> completely set hard and you did remove the top layer, grinding it in a
> pestle and mortar would get rid of any lumps. Yes! this is the hard way,
> but the question was could it be done. layers can be seperated at the dry
> stage . Sometimes necessity forces inefficiency on us all. I was just
> answering the question that it could be done. I did not expect Ted to take
> my suggestion up as a sound methodology but as an all is not lost
> suggestion. If you are short of clay and or time .
>
> I suppose I could have advised throw the grelog out and start again I
> would throw the least suspect glaze out. Not because of my deep respect for
> my work but because of the money I would have lost if it goes wrong.
>
>
> Regards from Paul Taylor
> http://www.anu.ie/westportpottery
>
vince pitelka on mon 5 feb 01
> i would like to get into some terra sig if it is what i think it is
> ..ithink its when you put black over earthenware and then scratch out a
> design? anyways i can throw those shapes in the museums like the
> panethenaic amphora, alabastron, kylix, pyxix
> etcetera and i have yet to try the terra sig , as i have spent all my
> time trying to learn how to throw, so what do you just mix iron with fine
> slip or what ?
Dayton -
The anceint Greek red-black method is very complex, and involves a delicate
firing schedule. Few have ever matched it.
Terra sig by itself is not complex. The technique you are referring to is
sgraffito, where you apply a coat of sig or slip, and then scrape, carve, or
incise back through the coating to show the contrasting color of the
claybody beneath.
To get more info on terra sig check
www.digitalfire.com/education/glaze/terasig.htm
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/
dayton j grant on mon 5 feb 01
i would like to get into some terra sig if it is what i think it is
...ithink its when you put black over earthenware and then scratch out a
design? anyways i can throw those shapes in the museums like the
panethenaic amphora, alabastron, kylix, pyxix
etcetera and i have yet to try the terra sig , as i have spent all my
time trying to learn how to throw, so what do you just mix iron with fine
slip or what ?
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