Raku dolce is a special technique created in the Roman Era during the first century A.D. This production was called Terra Sigillata Arentina and was mainly for culinary use; bowls, plates and drinking cups. The clay was a coral colour and this is a particular detail of this type of technique. The surface was decorated by a master with really good skills and they put a stamp called Sigilla to represent their production. The representative town for this type of technique was Arezzo (Italy) where a lot of artisans produced really high quality items. The name Terra Sigillata is used nowadays, to define the pottery with a special slip and a ferrous clay with a lot of potassium and sodium.
Rainwater and salt are key ingredients for this special technique. Mix deflocculated clay and water. Leave to stand for 24 hours. Siphon off the top part and discard the sludge at the bottom. The top part is already Terra Sigillata and it’s ready to use. Sometimes it is necessarily to repeat this process a few times if there is too much sludge. Pieces are made with a finishing touch, without sharp edges. The slip must be the same clay as that one used to create the pieces. Terra Sigillata absorbs a lot of smoke, therefore about 3 coats of it should be applied to the pieces. Between each application the pieces have to dry up. It is indicated to polish the surface with a soft fabric.
It is important not to leave fingerprints into the surface to obtain shiny pieces. Colours depend on the clay used; for example with Terraglia the colour comes out white but with majolica the colour will be yellow or orange. Each type of earth has got different pigments, so it’s very interesting experimenting the technique with a lot of clays. The best way of firing Raku Dolce pieces is in an electric kiln to 1000°C, like a normal bisque. Then the second firing process take place, this time in a Raku kiln up to 600°C. When the pieces come out we need to put them in wet sawdust and when they are cool they are ready. It’s possible to apply a mixture of water and wax onto their surface to animate the colours.