Oil Paintings And The Varnishing Requirement

By Author: Anthony Keith Whitehead
Total Articles: 21
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Why Oil Paintings Are Living Things
An oil painting can be said to be a living thing in the sense that it is organic. The relevance of this is that it changes over a period of time and does not stay same. Some changes are transitory, others, to varying degrees, more or less permanent. These changes occur because of the kinds of materials used in the production of paints. These materials themselves are subject to change e.g. the pigment which gives it its colour, which is subject to change.
The need for an oil painting to dry is a major problem, although it can be dealt with in one way or another. This is in contrast to some other mediums, such as watercolours or acrylics; the former dry almost immediately and the latter are dry within a very short time. The longer drying time needed for oils has its advantages and, for example, means that a painting, or part of it, can be reworked, changed and further developed. But an oil painting is generally reckoned to need up to twelve months before it is dry, and some may need even longer.
Differences In Drying Times
Some colours take longer or shorter to dry than ...
... others; but a given colour take longer or shorter than others depending on its manufacturer . Ingredients can differ as between different producers of oil paints and this can affect drying times. Titanium White, for example, dries much faster than other colours. Also, Winsor & Newton manufacture an alkyd range of oil paints that are fast drying and, usually, will be touch dry overnight. “Touch dry”, however, means no more than that; it is not an indication of complete dryness; it is simply that it can now safely have additional layers of paint applied over the earlier one(s). Remembering this, alkyd can also be used through various mediums to which it has been added so that, mixed into a particular oil paint colour, drying time can be accelerated, often causing the paint to become touch dry overnight.
The Times Of Varnishing.
There are two stages at which an oil painting can be varnished: as soon as the paint is touch dry and after about twelve months following its completion. (Although some may sometimes recommend six months, it is safer and better to wait the longer period). This may sound contradictory, but the two statements are reconciled in the way and for the purpose that varnish is applied. So we have “touch dry” varnishing and “final varnishing.

Varnishing When A Painting Is Only Touch dry
Some varnishes can be applied once the painting is dry to the touch. The varnish used at this stage is different from that used after the twelve months limit. It tends to be used by professional artists who cannot afford to have pictures hanging around (no pun intended!) for six or twelve months. The kind of varnish used is something such as Daler-Rowney Retouching Varnish, although there are a number of different makes. This is often used to recoat an oil painting when it has become somewhat dull, but this type of varnish can also be applied as a temporary coating to protect the surface of the painting. It is quite safe to do this but, of course, one needs to be sure not to mix up the different types of varnish.

Varnishing As A Final Touch
Once the oil painting is fully dry, the final varnishing can be given. The varnish can be one of the many sold specifically for this purpose, such as, for example, Artisan Gloss Varnish or Matt Varnish or Satin Varnish depending on the kind of finish you prefer. Some people mix gloss and matt varieties in equal quantities, which is an alternative that might be preferred. It must not be applied in less than six months although, as advised above, twelve months is safer, -- and for safety's sake, not less than that even over alkyd quick drying oils.

The reason for not varnishing under this period is simply that oil paints do take a lengthy period to dry. If the varnish is used prematurely it will have a similar effect to applying a later coat of oil paint over an earlier one that is not yet fully dry.

Hints On Applying Varnish
Once the painting is dry (and that may especially take longer than six months if an impasto method has been used compared to painting with thin coats), it is advisable to gently wipe the surface with a dry, soft cloth to remove any dust. In what follows be careful not to apply the varnish too thickly.

You can use either an aerosol or a brush to apply the varnish. If using a brush it is generally better to use a larger than a smaller one since it will cover a greater width with each stroke and make the tendency to miss areas between strokes less likely. The overall covering will also tend to be smoother. The actual width will obviously depend on the size of the painting.

Lay the varnish on as swiftly as possible and avoid going over areas already treated once. Periodically hold the painting horizontally towards the light to ensure no area is missed. At the same time, make sure that no bristles have become detached from the brush – this can easily happen, even at the varnishing stage, and even with quite expensive brushes there is always such a risk, especially with a new, or relatively new brush.

To ensure the varnish does not run, lay the painting flat to dry. Running should not be a great risk unless the varnish has been applied much too thickly. Although varnish for oil paintings tends to dry quite quickly, it is also a sensible precaution to make as sure as possible that the varnishing is done in a dust free area.

And Finally…
The purpose of varnishing is mainly to protect the surface of an oil painting, but there is also another advantage. The paints used on any given picture will vary not only in colour but also in the degree of gloss or dullness. Hold a finished painting up to the light before varnishing to see this more clearly. Applying a coat of varnish will give the painting an overall degree of homogeneity in its gloss or matt finish and this will help to bring all its elements together, thus improving its general appearance.

AUTHOR: A K Whitehead
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All the paintings in oil here are by A K Whitehead, who is aself-taught artist, and are original oils and not copies. The approach is traditional, making use of various techniques, including impasto and glazing. This link will take you to the main categories of landscapes, seascapes, snowscapes, waterscapes and still life and all are provided with free frames and fastenings. Free delivery is also included within the UK.