The Double Reverse Technique is also referred as the “Ravenna Technique”
It is a 1500 year old method, handed down from the Roman/Byzantine times.
It is currently used by many Italian professional mosaicists (Maestri), and restorers.
Typically this method is applied when it is important to see the work during the creation process, as it will appear when completed.
The operator can constantly control the final result of the work, which is important especially in human figures.
Briefly, the tesserae are set into a temporary bed of putty, slaked lime, or clay, where they can be placed and moved at will until the wanted effect is achieved.
The temporary bed will remain moist for long time, even months as long as it is covered with plastic.
That means you can leave it, and come back to it when you are ready to work again.
Once finished, the mosaic is lifted (Strappato), cleaned, and glued on its final destination, typically wooden board, furniture, objects,…
In Ravenna the tesserae are still cut by using traditional tools, such as Hammer + Hardie.
In this video Luciana Notturni explains the Double Reverse Technique: