If oil and acrylic paintings are well cared for and are cleaned occasionally, they do not necessarily have to be varnished. However, varnish will certainly protect the paint film from any damage cause by scuffing, humidity, dust and atmospheric pollutants. The varnish itself will eventually be stained by these elements, which is why a removable varnish is preferred by restorers; when it becomes dirty or cracked, it can be removed with solvents and replaced.

Varnishing oil paintings

It is very important that an oil painting is completely dry before final picture varnish is applied; this can take anything from six months to a year, perhaps more for thickly impasted paint. Oil paint expands and contracts as is dries and premature varnishing may cause cracking as varnish is less flexible than oil paint.
For that reason I use retouching varnishing to protect the paintings which can be applied as soon as the paint is touch-dry, normally within a few days. This will protect the surface until it is dry enough for final varnishing.

Varnishing acrylic painting

Despite popular belief to the contrary, it is advisable to varnish completed acrylic paintings as oils; although acrylic dries waterproof and as tough as nails, it picks up dirt just like any other kind of paint. A coat of varnish gives your paintings extra protection and also enhances the brillance of the colours.

details