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ts
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Reunion Island
939 Posts
Enviado - 22/03/2003 :  19:37:46  ver perfil  Enviar E-mail  Responder con comillas
www.toutblanc.org

sin más.

ts
Moderador


Reunion Island
939 Envíos
Enviado - 22/03/2003 :  19:39:19  ver perfil  Enviar E-Mail  responder con comillas

perdon:

www.toublanc.org

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SINSONTE
Miembro



229 Envíos
Enviado - 31/03/2003 :  00:07:16  ver perfil  responder con comillas

Hola ,ts, he tenido que marcar toda la direccion porque tal como la escribes no sale directamente de tu email.Tienes que escribir el http:// y el www, si lo lleva,para que directamente salga la pagina correspondiente.Es automatico si lo escribes entero.En la otra direccion que has enviado la he tenido que buscar por buscadores y me han salido 600 ó 700 respuestas y no es cuestion de verlas todas.Si verdaderamente estas interesado en que la veamos todos ,por favor,vuelve a repetirla entera.Muchas gracias.
Dudo muchisimo que las piezas que muestra la web que indicas sean de tierra sigillata aunque ponga"sigillé".Si estoy equivocado espero que alguien me lo confirme.Saludos


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kandiles
Miembro


Spain
402 Envíos
Enviado - 01/04/2003 :  00:48:59  ver perfil  Enviar E-Mail  responder con comillas

no pondria la mano en el fuego, pero tranquilamente podrian se de terrasigillata. De todas formas a mi me han parecido unas piezas muy y muy bien trabajadas. Saludotes

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ts
Moderador


Reunion Island
939 Envíos
Enviado - 02/05/2003 :  20:22:24  ver perfil  Enviar E-Mail  responder con comillas

salud al foro,

(con especial atencion a kandiles y sinsonte)

primero, pedir disculpas poe el retraso y por la mala direccion...(http://www.toublanc.org/)

y segundo, que son piezas engobadas de tierra sigilata, seguro, de distintos colores y demás, pero sigillée sigillée de la buena.

si encuentro mas direciones (esta vez sin errores !!!) de tierra sigilata las mando

a+

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ts
Moderador


Reunion Island
939 Envíos
Enviado - 02/05/2003 :  20:26:59  ver perfil  Enviar E-Mail  responder con comillas

salud a todos,

otra pagina de sigilata. Esta vez es raku nu (pelado)...pero sobre sigilata.
http://www.objekta.ch/Gioria_Fabienne.htm
a+

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SINSONTE
Miembro



229 Envíos
Enviado - 02/05/2003 :  21:43:31  ver perfil  responder con comillas

Hola TS me alegro de que ma hayas sacado de dudas.Yo no entiendo nada de terra sigillata y me pareció que había metalizaciones que no se que tipo de arcillas pueda darlas.
Las partes negras supongo que estan hechas con reducción fuerte para obtener el óxido de hierro negro y las partes rojizas ¿Se cuecen primero y ya no son reducibles o es al revés?
Me gustaria que me explicarais mas de este procedimiento así como para obtener el maximo de tierra sigillata de una arcilla.¿Valdría el molerla intensamente antes de la defloculacion?¿Acaso en molino microbolas?
Estoy ansioso por que me informeis al maximo.Desde luego resultan unas piezas bellisimas.Saludos

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ts
Moderador


Reunion Island
939 Envíos
Enviado - 06/05/2003 :  06:14:19  ver perfil  Enviar E-Mail  responder con comillas

salud Sinsonte,

te respondo en "dudas...."

por cierto, tengo los apuntes en ingles para hacer sigilata....te los podría mandar si te interesa...( algo más de 1Mb !! lo siento)

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SINSONTE
Miembro



229 Envíos
Enviado - 06/05/2003 :  20:56:46  ver perfil  responder con comillas

Hola,ts, si que me interearian esos apuntes porque supongo que con 1 Mb debe poner muchas cosas interesantes o tiene muchas fotografias o dibujos.¿Lo mandas aqui al foro,o necesitas una direccion de correo?Saludos.

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nefer
Miembro



30 Envíos
Enviado - 07/05/2003 :  00:32:22  ver perfil  Enviar E-Mail  responder con comillas

hola TS yotambien quiero las paginas en ingles las mandas al foro?

nefer Ir arriba

ts
Moderador


Reunion Island
939 Envíos
Enviado - 07/05/2003 :  05:12:22  ver perfil  Enviar E-Mail  responder con comillas

salud a todos,

que digo yo que igual es muy grande para mandarlo al foro...
mejor mandarlo a direcciones particulares...

nefer, ya te lo mando. sinsonte, mandame una direccion y ya está....

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SINSONTE
Miembro



229 Envíos
Enviado - 08/05/2003 :  21:28:22  ver perfil  responder con comillas

Hola TS recibi las las 4 hojas .Te he escrito y he dejado mi buzon vacio.Gracias

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SINSONTE
Miembro



229 Envíos
Enviado - 10/05/2003 :  01:32:12  ver perfil  responder con comillas

Hola ts,recibida la segunda parte.Muchas gracias

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nefer
Miembro



30 Envíos
Enviado - 15/10/2003 :  16:48:25  ver perfil  Enviar E-Mail  responder con comillas

hola ts como estas?te mando mi nueva direccion que es cascabel07@att.net.mx haber si haora me puedes mandar las hojas de terra sigillata haber si me lle gan te lo agradeceria muchisimo saludos


[/quote]

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meryan
Miembro


Argentina
229 Envíos
Enviado - 13/08/2004 :  18:49:36  ver perfil  Enviar E-Mail  responder con comillas

Tarde pero seguro, yo no hago raku, y no sé qué es sigilata, pero me gustaría leer un poco sobre el tema...
TS: ¿si podés me mandás a mí también los apuntes?, gracias....

María Eugenia Ryan Ir arriba

fernang
Miembro



14 Envíos
Enviado - 14/08/2004 :  21:31:15  ver perfil  Enviar E-Mail  responder con comillas

espero les ayude....

Our Ceramics Guru Offers This Tip On: Making terra sigillata

Terrasigillata
Using a glass or clear container, dissolve 5 gms of calgon sodium hexametaphosphate, which is a deflocculating agent) in 2 pints of rainwater(sodium crbonate or potassium carbonate can also be used). Add 230 gof dry crushed clay, sieve through a 60 mesh (or finer). Shake container, mix and leave for three days minimum. The clay will settle into 3 layers with a layer of clear water on top, siphon off this clear water and discard. The next layer is the terrasigillata(colloidal slip).
Note: White clay needs 0.3% sodium silicate......and water to clay ratio of four to one, to deflocculate.
Red clay needs 0.5% sodium silicate......and water to clay ratio of three to one to deflocculate. Terra sigillata is high in alumina. It may be hardened by adding 3-4% sodium silicate to the recipe after deflocculating the sigillata.
'Making terra sigillata' Questions?


Our Ceramics Guru Offers This Tip On: Terra sigillata: Application and Firing

Application and Firing: Terra sigillata can be applied by spraying, dipping or brushing at all stages of construction. Apply several coats and burnish or simply polish with your hands or a soft cloth when damp/dry to the touch. Polish between coats for the glossiest surfaces. Terra sigillata can be fired at any temperature but the polished surface will start to break down when fired over cone 04. Use as a slip/engobe up to cone 10 and above.
'Terra sigillata: Application and Firing' Questions?


Our Ceramics Guru Offers This Tip On: Terra Sigillata: History

History: Historically terra sigillata has been used as a sealer and decorative coat on pottery for thousands of years. Common examples are the Roman red black pottery, and the black polished Native American Indian pottery of the Southwest. Contemporary uses include raku, smoke firing and other techniques that emphasize the surface.
'Terra Sigillata: History' Questions?


Our Ceramics Guru Offers This Tip On: Terra Sigillata: Types

Types of Terra Sigillata: The basic mix is a white ball clay. Used alone it is a beautiful satiny white. Mason stains and other colorants can be added to give a wide range of colors. Use between 3 and 10%. To eliminate weighing use 1/2 or 1 full standard Mason sample pack per pint of terra sigillata. White, red and tan slips can be intermixed to yield different tones.
'Terra Sigillata: Types' Questions?


Our Ceramics Guru Offers This Tip On: Terra Sigillata; Description

Terra Sigillata (or earth seal) is a slip containing very fine particles. It is created by a process of separation. We grind, using a ball mill, specially selected clays and water until the particles are extremely small. Deflocculant is added and the mixture is allowed to settle for twenty-four to forty-eight hours. The fluid left on top after settling is terra sigillata. Longer settling will yield a finer, higher quality product. After application, simple polishing with your hands or a soft cloth will shine terra sigillata to a high gloss. This smooth surface is ideal for decoration especially with smoke firing and other primitive techniques. After firing you will have a smooth, weather resistant coating much like a glaze.
'Terra Sigillata; Description' Questions?


Our Ceramics Guru Offers This Tip On: Terra-Sigillata: Description

Terra-Sigillata is a slip, made of clays whose particles are extremely fine. Like slip or en-globe - which it basically is - Terra-Sigillata appeals to those who wish to develop an intimate relationship between the surface of their work and its form, and who respond to the way in which the Terra-Sigillata becomes an integral part of the clay body rather than coating the surface like a glaze. After the final firing the forms are hand-polished with Tung Oil to achieve a more durable surface. Terra-Sigillata means "sealed earth". It was used by the Greeks and Romans before the invention of glaze.
'Terra-Sigillata: Description' Questions?

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Terra Sigillata is the new craze, there is talk about it where ever you look. There are BBS entry's full of questions and information, magazine articles, and plenty of potters trying one or more of the millions of recipes. The technique derived from ancient Greek pottery techniques, dating back to 2500 BC.
The technique of Terra Sigillata, is quite different from glazes common today. Terra Sigillata is a fine solution extracted from the original clay used for the wares, with no additional colorants added.
The method of Terra Sigillata is believed to have been found by accident Greeks. Terra Sigillata can only be made from the finest particles in the clay body. The separation of these particles form the coarser material in the clay was accomplished by sedimentation.
In Medieval times a solution of clay, water and potash were mixed together, and allowed to stand for forty-eight hours. The solution would then separate into three segments. The upper most segment was carefully removed, and then thickened by means of evaporation.
Today, Calgon bath preparation serves as a convenient substitute for potash, as it has similar ingredients. I have also found that the origional Calgon must be used. Today there are many new and diffrent recipies and methods.
When the mixture is applied to the dry green ware, and allowed to dry before firing, it already has a sheen caused by the horizontal alignment of the particles. A luster can be accomplished by polishing. I have seen and tried many different techniques of polishing, but I find that polishing with my bare hand works the best with the Sigillata solution I make. Some say that you can polish with a cloth, a tissue, a plastic grocery store bag, and a chamois.
Partly to economize fuel, ancient Greek pottery was fired only once, but primarily because the Sigillata technique adhered better to an unfired surface.
Vince Pitelka - vpitelka@dtccom.net
Home 615/597-5376 Work 615/597-6801 FAX 615/597-6803
Appalachian Center for Crafts, 1560 Craft Center Drive, Smithville TN 37166
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 twelve 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 as a coating for sanitary sewer pipe - not very romantic. Schumann discovered the real secrets of terra sig, which had been lost for about 1600 years. Schumann's info guided me to the current system I use.
A glaze hydrometer is required below. A winemaker's hydrometer will not work, because it measures fluids lighter than water. A proper glaze hydrometer should have a scale reading from 1.00 (the weight of water) to 2.00, in 100ths.
I usually use redart, ball clay, or goldart as a starting point. Start with a small amount of hot water, and into it dissolve the deflocculant - 0.25% (1/4 of 1%) soda ash AND .25% sodium silicate (the two together seem to work better than either by itself), based on the dry weight of the clay to be made into terra sig. Once dissolved, 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 or goldart slip or 1.15 for the ball clay slip. For a full five-gallon bucket of initial mix, this will take about 16 lbs of redart or goldart, and about 12 lbs of ball clay. Place the bucket with this mixture up on a table and LEAVE IT UNDISTURBED FOR EXACTLY 20 HOURS. After the 20 hours has passed, 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, generally those less than one micron (1/1000 of a mm.) are still in suspension, due to atomic vibration and deflocculation. The top layer IS THE TERRA SIG. Do not discard ANY MATERIAL AT THE TOP, even if it seems quite clear, because it will contain the very finest particles.
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, and do not move it for any reason. If you must move it, remix it and start the 20 hour settling period again. Once the siphoning is started, slowly feed the tip of the siphon down into the mix as the thin liquid is siphoned off. Keep the tip close to the surface, so that it periodically sucks a bit 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 happens, 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 you 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 unusable, 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 several 24"-diameter terracotta evaporating dishes with a raised 2" edge. Another excellent mold for such dishes is one of those round dished plastic snow-sleds. I usually just siphon into a five-gallon bucket, and pour that into one of the evaporating dishes. 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 (unless you are welding or grinding or woodworking in the vicinity). 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 specific gravity. If it is still thin let it evaporate some more. If it is thicker put it in an appropriate container and add water.
If you wish, you can let the sig dry completely, and keep it around until you need it. When you anticipate needing it, slake it in water for several days, mix well with a jiffy mixer, and adjust to the desired specific gravity.
I originally used sig 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 1.17, depending on the clay used and the desired results. I apply the sig to bone dry clay, and get the best results when the clay is sanded. I use a wide soft brush, and I simply brush on repeated flowing strokes until I get an opaque buildup which begins to conceal the sanded texture (still very thin). As soon as I get as much sig buildup as I want, and the surface wetness 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 platelets 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.
Also, a properly prepared terra sig makes the very best burnishing slip. For burnishing larger forms, I apply a very thin smear coat of lard, which retards the drying of the sig and allows you to completely burnish the pot. But once you start burnishing, you must finish it in one sitting. If you leave it incomplete and allow it to dry, you must sand the surface, re-coat it, and start over.
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 50 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, at high-fire temperatures 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 like goldart 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. I have used both oxides and mason stains without ball-milling, and the shine is reduced slightly, but the results are still satisfactory.
Terra sigillata is a very smooth, lustrous coating of clay which resembles a glaze and is virtually waterproof. The name means "sealed earth" and has been used to refer to the Classical Greek Attic black-figure and red-figure painted pottery.
These days, the name terra sigillata is used to refer to an especially fine coating of clay applied to a ceramic piece.
For centuries the secret of making terra sigillata was lost and only in the middle of this century was the true nature of this material, the technique of its creation and use rediscovered.
I make my own terra sigillata from a white clay and the same red clay I use to make the pots.
The silkiness and shine of terra sigilatta is due to the plate like shape of the clay particles and the use of only the smallest particles. Polishing this surface with your hand or a soft cloth lines up all the clay ‘plates’ and gives the surface its shine.
It takes much time and care to get the right effect but the warm shine and silky texture of the terra sigillata as well as the subtle sense of fire and smoke brought out in the firing are some of the reasons that make it worth the effort.
Forming
My pieces are all formed using hand-building techniques using coils, slabs, drape molding and carving. I don't use a potter's wheel.
The medium sized plates are formed by placing a piece of clay on a convex mold and beating it into shape. This makes for a very strong yet light plate.
The small, covered boxes are made by forming a block of clay, letting it harden slightly, cutting it in half, carefully carving out the insides and adding a collar to fit the lid.
Bisque Firing and Decoration
After forming and drying, all pieces are bisque fired to 1000° C. in an electric kiln to harden them. After this they receive up to four coats of the white terra sigillata and are again fired to 1000° C to harden this layer. They are then decorated with the red terra sigillata using various techniques.
Each layer is polished with a soft cloth or with my bare hand to bring out the shine. They are then fired again to 1000° C. to harden and slightly seal this layer. More layers may be added and fired again, depending on the effect I'm trying to achieve. Each pot is fired at least four times.
Smoke Firing
My pieces receive their final coloring from the reaction of the terra sigillata to the heat and the smoke of the fire.
The pieces are "smoked" by wrapping each piece in newspaper, sealing it inside an envelope of aluminium foil and refiring it in the electric kiln to between 500° C. and 750° C. The amount of newspaper, the temperature used and the amount of time in the fire decide how the pot will look.
Finally, each piece receives a light coating of oil or bee’s wax. No other treatment is used.
Care
These pots are meant to be handled. The tactile aspects, the feel of the surface, how it fills your hand, the weight and balance of a pot, are as much a part of the experience of pottery as the visual aspects and the function.
However, unlike a glaze, which is a coating of hard glass on the surface of a pot, terra sigillata is a soft coating of clay which can be scratched by a hard, sharp object.
The surface is also very slightly porous and may absorb some liquid if left for a long time.
Treat them gently.
- Wipe with a damp cloth or hand wash gently in warm water, no soap. Dry thoroughly with a soft cloth and let stand for a while until completely dry.
- If the color or the blacks start to fade a bit; apply a small amount of a good olive oil to a soft rag and polish. The surface, being very slightly porous is a bit thirsty and has absorbed all the oil or wax that was applied after they were finished.


Reducing in an Electric KilnAvoid premature kiln ageing Many potters, ceramic artists and hobbyists have electric kilns, but not gas or woodfiring kilns at their disposal. This poses a problem if you want to create reduction glazes such as copper reds or celadons. These glazes require a reduction atmosphere, where the kiln is starved of oxygen. Free carbon in the form of carbon monoxide is formed. (This is also why reduction firings should be done in very well ventilated areas. See the Toxic Materials Database for more info.) This is normally done by reducing the flow of fresh air to the kin interior, by closing off the flue (chimney). The oxygen inside the kiln is quickly used up by the combustible fuel (wood, gas or oil) and different chemical reactions take place than in an oxidizing atmosphere.In the reducing atmosphere, copper forms metallic copper instead of copper oxide. It is this metallic copper that gives copper red glazes their distinct color. Iron forms iron oxide (FeO2) in oxidation, but in reduction, ferrous iron (FeO) is produced, with its bluish, green or black hues.Reducing electric kilns is a problem. It is possible to throw in combustible materials through spy holes, but this is difficult. More importantly, the carbon tends to aggressively attack the kiln elements (heating coils), considerably shortening their life through corrosion. If creating a reducing atmosphere in an electric kiln is so damaging, what is the solution? There are two answers to this.1. Artificial ReductionIn artificial reduction, a reducing agent is introduced into the glaze itself. This is usually silicon carbide (SiC). Silicon carbide has a strong reducing effect on the other glaze materials. 1.5 - 2 percent should be enough to create the desired effects. The finest available grade (300 mesh or finer) should be used, so the material disperses as evenly as possible in the glaze, otherwise specks may appear. Sometimes bubbling of the glaze may occur (similar to a crater glaze), then soaking at top temperature is recommended.2. SaggarsYou can make your own special custom containers or lidded boxes in which you put your pottery along with some combustible material like coal or moth balls. When the organic material burns, it creates a localized reduction atmosphere inside the box. You need to work out the amount - too much will cause blackening through carbon trapping, too little and there won't be sufficient reduction effects. Above left: Saggar fired test tile with reduced cone 6 copper red glaze.You might think that oxygen will enter the container from the outside, but that isn't the case. Oxidation and reduction remain localized. This is also an effect that can sometimes be seen even in a wood or gas kiln, where there may be areas of local oxidation, despite an overall reduction atmosphere (see image). More ArticlesFiring Techniques


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