This technique was developed by Sven Palmqvist for Orrefors in 1948 after a trip to Italy. He was fascinated by the byzantine mosaics, windows and patterns that he saw in Ravenna. Upon his return to Orrefors, these inspired him to recreate these patterns in glass. It is similar to the Ariel technique. A colored glass layer is put on top of a clear one and these are then flattened. The motive is created by sandblasting away the colored layer of glass to expose the clear glass. Powdered colored glass or pigments are then scattered into the applied design before the whole is being encased with clear glass. Small air bubbles are trapped in the design, but their size and number are considerably less than with the Ariel technique. The Ravenna pieces are then reheated and given their final shape, usually as vase or bowl.
The most widely used colorpattern is a blue background with a rusty red (or brown) motive. There are some pieces with a white background and red/brown motives. Other colour combinations are even rarer. There are also some pieces which are so-called double Ravenna pieces. Here two layers of colored glass are used on top of each other.
Sven Palmqvist was the only person to work in the Ravenna technique at Orrefors. All pieces are signed and numbered, and can be dated exactly.
You can find all the date codes and/or serial numbers related to Orrefors Ravenna on the following link: Dating Orrefors Ravenna