|Mona Lisa Leonardo Da Vinci from google image|
During the Renaissance painters like Leonardo Da Vinci used animal skin glue to coat and size the canvas. Linseed oil was the base of most oil paints and was very acidic. The acid would eventually destroy the canvas, so it was necessary to coat the canvas with a protectant. Rabbit glue was most often used. In other forms rabbit glue could be used as a adhesive. If the paintings had not been coated master pieces like the Mona Lisa would not have continued to exist for us to enjoy today.