Varnishing a Painting

Last week in oil class, Charlotte brought a painting that she wanted to rework. The painting had not been touched for a couple of years. It is a lovely study of a Monet landscape. I suggested she use a retouch varnish before applying paint.
The procedure to apply retouch varnish is the same as applying varnish on a dry painting as a finishing coat. Retouch will give the paints a better surface to accept new paint. It brings out the color which has dulled since the oil in the paint has dried and leaves the paint less glossy.
Always clean or dust the surface with a lint free rag, like an old diaper, or a clean flat brush. If the painting looks dirty, you can wash it gently with a mild soap (I like Ivory) making sure to dry it thoroughly.
Apply the varnish with a flat brush. We poured the varnish into a shallow bowl and used a brush made for varnish because it has softer bristles. Paint broad strokes, don't go back over and over in the same spots, you want an even coat. Allow it to dry.
There are different brands of retouch and picture varnish. They are pretty much the same. Some artists prefer the glossy and some the satin. I have sometimes mixed the two. Lately I have been using a product called Soluvar for the final varnish. It is glossy. Damar varnish has a reputation for yellowing after a while, especially over the lights and whites. It is still the most used final varnish.
If you have an older painting that has a coat of final varnish that you would like to "bring back to life" you can take the varnish off with a light rub of turpentine or mineral spirits.
I have never done this before, and I probably would recommend taking the painting to a restorer or experienced frame shop.
If you have any questions, the manufacturers of the products are usually available. I would check their websites.