Winsor & Newton Artists’ Retouching Varnish is a UV resistant gloss varnish which gives temporary protection to recently completed oil paintings. But unlike Artists’ Varnishes, it is possible to paint on top of Retouching Varnish.
To achieve this, it is best to keep subsequent layers of colour as “fat” as possible (thinned with lots of medium) and apply them as finely as possible.
A layer of Artists’ Varnish should then be applied after the last layer of colour has been allowed to dry for six months.