Grades 6–8 · Arts & Music
How can a fresco become part of a plaster wall?
In buon fresco, an artist applies suitable pigments with water onto fresh lime plaster. The wall surface is still damp and chemically active. Timing matters because the final binding develops as the plaster changes.
In the diagramLime chemistry helps bind pigment into plastercarbon dioxide from the airfresh lime plaster → carbonate surfacewall supportpigment held within the changing mineral layer
Carbon dioxide from the air reacts with calcium hydroxide in the lime. This process, called carbonation, forms calcium carbonate. The developing mineral structure holds pigment within the surface layer.
The pigment supplies color while the changing plaster provides much of the binding structure. This differs from paint in which an added oil or polymer dries into a separate film. Fresco joins image-making to the wall material’s own chemistry.
An artist usually works on an area that can be painted while conditions remain suitable. Once that surface has set, later additions behave differently. The surviving image therefore records both a creative design and the practical sequence of applying pigment to fresh plaster.
About this explanation
Starting knowledge: Know that pigments provide color and that air can participate in a chemical change at a surface.
Sources
- Getty Research Institute — Art and Architecture Thesaurus: Buon Fresco