The churches were built using local materials: stone, limestone, wood and slate. Stone was worked into an ashlar, joined together using limestone mortar to make the walls and vaults. Wooden beams and slates were used for the rooves.
A mix of limestone mortar made with sand, limestone and water was applied to the walls and a preliminary sketch or ‘sinopia’ was then drawn on top. Finally, with the mortar still fresh, the coloured pigments were applied, diluted with water.
Used to paint on wood or to apply the final touches to murals. In this case, the pigments were mixed with egg yolk.