As presented in the workshop on June 18th and June 15th, 2021. (Ed: Gaps in the section are added for alignment and to make the comparison easier)
Obvara Pottery (Baltic Raku)
Obvara pottery, also known as ''Baltic Raku'' is an easy but unique technique that is related to traditional raku firing, but differs in that it uses a rye-flour mixture as a coating. Obvara can be used in barrel kilns, fire pits and saggar firings.
This fermented ceramic technology is 4 to 6 centuries old, wherein glazes enriched with metal oxides are replaced by rye-flour yeast. This odd, nearly forgotten pottery tradition is not limited merely to the Latgale region but is found in the three Baltic European nations of Estonia, Latvia, and Lithuania, as well as Belarus and Russia. These lands, across the Baltic Sea from Sweden and south of Finland, are united by a tradition of rye cultivation and black bread. This pottery type is known in various languages as ''hardened ceramics'', ''black pots'', ''sourdough pottery'', and ''fermented ceramic''. The English versions are called ''hardened ceramic'' or ''fermented ceramic''. Like traditional Japanese and American raku, it consists of manipulations to just-fired,
and still-glowing pottery right after it has been removed from a kiln.
The ware is dipped into this yeasty solution, with a thickness somewhat akin to thin waffle batter. This ''goo'' renders a very kitchen-like or baking-like process, and the
aroma is like baking bread. Chemically, the yeast enhances the gluten strands of two of the flour proteins.
When your piece is pulled from the bubbling, sticky goo, the gluten attaches and forms a sort of resist on the surface. The pot stays lighter where the gluten attaches - where it does not attach, the flour in the mix is left to burn and carbonize the pot. The longer your work stays in the air after pulling it from the goo, the darker the carbon marks will be. Smoke from the burning flour creates a hazy quality on the pot. By using some rotating moves while holding the smoking pot, you can use the smoke to help decorate the surface. When your piece has developed the finish you desire, it is plunged into water to halt the process. Variables to the finish can result from double-dipping, how quickly or slow you dip, in what direction you dip, and the temperature of the pot. Thin places in the walls, raised decorations, and pot edges will cool more rapidly than the main body of the piece, and accept the goo differently. The cooler sections, especially the edges and heavy textures, will generally be lighter or white in comparison to the rest of the work. Hotter pieces tend to become darker when dipped.
If the pot has cooled too much, the carbonizing won't happen, and the piece will become a bland-looking tan. There is about a 200-degree window where all the action occurs. In general, the hotter the pot is when going into the goo, the darker it will be.
\The hotter pots will create a near-glossy black finish and the cooler pieces will be a less than-dazzling tan. If you hold your piece in the goo too long, it will cool below the threshold of carbonization.
It is possible to ''cook'' the goo by adding too many hot pieces too quickly.The entire batch is only about 3 gallons, so thi,s can happen easily - and you end up with an extremely yucky porridge.
This process can be highly odiferous - think of it as lousy beer going into the mix, and freshly baked bread emerging from the goo. It is a good idea to mix it in a temperature controlled room, but to not let it hang around too long.
From our website as of June 18, 2021. Our website page regarding Obvara is edited after that date from time to time with additional information and resources.
Obvara pottery, sometimes referred to as "Baltic Raku" is a simple and primitive ceramic technique that is akin to traditional raku firing and frequently used by pit fire, barrel kiln and saggar fire practitioners. But obvara firing is unique enough to hold a place of it's own.
“Fermented ceramic is a 4-6 centuries old ceramics technology where the glass-like glaze enriched with metal oxides is replaced by rye-flour yeast. This peculiar, half-forgotten pottery tradition is not the cultural heritage of just a narrow Latgale region, but it is common to the three Baltic countries (Estonia, Latvia and Lithuania), Belarus, and Russia, the territory that is united by a tradition of rye cultivation and black bread. Every region has its own name used to designate this type of ceramics: 'rūdītā keramika' (hardened ceramics) or 'melnie podi' (black pots) in Latvian, 'raugo keramika' (sourdough pottery) in Lithuanian, 'обварная керамика' (in Russian scalded ceramics) 'poripott' in Estonian. The English version of the technique is 'hardened ceramic' or 'fermented ceramic'. It is a unique local tradition that is practically unknown outside the indicated region. Nevertheless, at the same time it possesses some similarity with the world-famous Japanese and American raku techniques, whose essence, from the American point of view, is manipulations with just fired and still glowing pottery after it has been taken out of a kiln." http://balticraku.eu/en/balticraku/
But before you go and Google "Baltic"...this is the area across from Sweden and South of Finland. Some of the old Russian "states" if you will. But it you are really into history and interesting factoids (like finding out about the Singing Revolution and the Baltic Way) visit https://en.wikipedia.org/wiki/Baltic_statesen.wikipedia.org/wiki/Baltic_states
Essentially, the unglazed piece is taken from the kiln at something around 1400 degrees and dipped into a yeasty mixture, something like a thin waffle batter (we sometimes refer to it as "goo"). The goo is a simple mixture of water, flour (any bread grain will do in our experience), yeast and sugar. It's a very "bakerly" or "kitchenery" process...if you know anything about bread baking you will understand what is going on with the mixture. Some folks talk about the mixture "fermenting" but in reality one is developing an environment where the yeast will enhance the development of the gluten strands from two of the proteins in the flour.
Yes. We have tried various flours: enriched, wholewheat, bread, cake, semolina and so forth. We have added extra gluten flour to the dry mix. There is very little visible difference between these experiments in the finished work because of the type of flour.
We have tried natural dye stuffs and that was ineffective. Most likely the dye chemicals burned off, as most organic matter would. Even the flour is turned to black carbon traces.
As the piece is removed from the goo, the gluten attaches to the pots and forms somewhat of a resist on the pots. As the pot is removed the gluten is bubbling and gooey. Where the gluten attaches, the pot stays lighter (the "white" patterns in the examples). Where the gluten does not stick, the flour in the mixture is left to burn and carbonize the pot. The longer the pot stays in the air after removal from the goo, the darker the carbon markings will be. There is sometimes some smoke that comes from the burning flour, which leaves a hazy quality to the piece. With some deft maneuvering that smoke becomes a decorative element to the pot. When the piece has developed a look that we enjoy it is placed into water to stop the process. Dipping the piece into the goo at various speeds, double dipping and the direction of the dip has a lot to do with the color development as does the temperature of the pot. Edges, thin places in the walls and raised texturing will tend to cool faster and accept the goo differently than the body of the pot. Those cooler places, particularly heavy textures and edges will generally be lighter or white compared to the rest of the piece.
The pieces begin to cool immediately as the kiln is opened (duh). Hotter pots tend to be darker when dipped...hotter areas of a pot react the same way. Lips and ridges cool more quickly, so are usually lighter. If the pot is too cool (it's all relative :-) )...the carbonizing will not develop and again, the pot will be a rather bland tan(ish) hue.. There is about a 200 degree window where all this action takes place. Timing is important as the pot is cooling rapidly through that heat window.
Generally speaking, the hotter the pot going into the mixture, the darker it will be. Nearly glossy black pots are from the hotter side of the firing range and tan pots are usually from the cooler side of the range. Really hot pots held in the mixture longer will yield fewer patterns. Cooler pots held in the mixture longer will possibly not carbonize as they cool below the threshold where carbonizing can take place.
Because cooling has such a profound affect on the color of the pots done in obvara and our pieces tend to be small, we work extremely fast and efficiently. A typical firing will encompass between 200 and 400 pieces...which brings up an interesting situation...
It is possible (been there and done that too) to "cook" the goo by adding too many substantial pieces too quickly. The goo heats up and everything thickens fairly quickly. Part of this is because we're working with fairly small batches of material...a typical goo batch is about 3 gallons. We have essentially cooked the batch of goo into a porridge...an unappetizing porridge.
Because we do this process so often, we have developed a method of controlling the development of the goo. We set the mixture in a temperature controlled t(r)oom. Because this stuff smells awful...not having it sit around in the studio is a wonderful thing. I frequently refer to the "aroma" as bad beer going in and freshly baked bread coming out of the goo. Now that I think about it...a few corn chips and some bean dip and I'm doing mighty fine.