Is it necessary to varnish water-mixable oil paintings? Why?

Question:If so, how to do it so it's even & doesn't ruin hard-worked painting? Is it necessary? Are paintings we see in museums in the last 50 years varnished?

Best Answer - Chosen by Asker: If so, how to do it so it's even & doesn't ruin hard-worked painting? Is it necessary? Are paintings we see in museums in the last 50 years varnished?

Yes you need to varnish! Water mixable has nothing to do with finishing a painting. Oils, acrylics, and tempera paintings all need a protective coatings when finished. Spray varnish can be used for an even transparent layer. Paintings are revarnished at museums every 25 years, (or at least should be). That's about how long it takes for it to turn yellow or cloudy.

Varnish gives a protective coat that helps keep a painting from scratches and aging as it helps reduce oxidation and dust and keeps other abrasives away. Modern varnishes also have some UV protection that keeps the color from fading. YES, paintings from the last 100 years have a varnish protective coating. It should be applied about 6-12 months after the painting is finished to give it time to thoroughly dry and "cure".