Operation of applying a layer of varnish to a painting or another object. Both in the pictorial technique and in restoration, the intervention has the function of defending the colours from external agents and to improve optical characteristics of the object, creating the necessary shine. The application of the varnish should be done when the painting is perfectly dry (for example, for an oil painting, at least eight-twelve months after its completion, and various days after a painting is restored when glazing is used), utilizing a brush or spraying the solution with the use of a compressor. The final effect (that is a greater or lesser shine of the surface) may be controlled by varying, other than the components of the varnish, the dilution, the temperature, the volatility of the solvent and, for spray varnishing, the pressure and the distance from the painting. The fundamental function of varnishing is noted by Giovan Battista Armenini (1587) who underlines its goal "to revive and bring out the colours, and to maintain them beautifully and vivaciously for a very long time."