Heritage conservation and restoration paintings: cleaning

Eliminating these is no easy task and requires testing with combinations of different solvents in a very controlled manner.

It is true that the removal of old oxidised varnishes returns a renewed look to the artwork, restoring its original appearance, but this may not always be the case. Throughout history, many artists and even art schools, have used glazing as a painting technique. This consists of applying semi-transparent layers of coloured varnish to achieve a depth effect which is impossible by just mixing solid colours. As an example, we all know that the colour orange is obtained by mixing red with yellow. In order to achieve the same colour using the glazing technique, several layers of reddish varnish would be applied over a yellow base.

Therefore, the total removal of varnishes should be avoided without a thorough study and prior analysis of the artwork, as this could irreversibly remove layers of paint intentionally varnished by the artist.