Obvara firing is a technique originally used to seal low fire pottery. It probably originated in the Eastern Europe during the Middle Age’s. It is a revival of the process executed in Ukraine and the Baltic’s. It is nicknamed “Baltic Raku”. The solution is a mixture of flour, yeast and water. To proceed with this technique the piece has to be very smooth and therefore finished with the Terra Sigillata touch. Three layers will be enough to have a good result. The mixture is produced three days in advance before the firing performance. This permits the mixture to become acidic and leave colours on the piece.
OBVARA FIRING TECHNIQUE
The best clay is stoneware, due to the high thermal shock the piece will receive. The creation is normally bisqued before the final Raku firing, but it’s not necessary. It is also possible to fire it in one go. Using a raku kiln to fire is a good solution for this technique, and the temperature needs to reach 970°C otherwise the mixture won’t be able to colour the pieces. They are removed one at the time, dunked into the brew and then quickly into the water. Then the air will cool them down. The brew burns quickly on the surface of the pieces and gives the effect to it.
The colour changes in just a few seconds, and becomes darker if the pieces are kept inside the mixture. The water stops the burning process so colours will change again. When the piece is cool it’s possible to apply a mixture of water and wax to the surface to animate the colour and remove a yellow patina on the surface. It is better not to use sandpaper or abrasive sponges to clean the piece as they will remove the effects on the surface.