Oiling Out and Other Techniques
The Causes of ‘Sinking’
When you have areas of ‘sinking’ on an oil painting these show as dull patches, many things can cause these sunken, dull patches and it is all due to varying levels of oil in the paint used. This can be due to the use of too much water, not enough oil in the latter layers of paint (fat on lean), too absorbent a ‘ground’, the underlying surface. Not enough painting medium in the latter mixes especially in mixes containing a high proportion of the earth colours are most likely to appear dull, the reason for this is that the pigments actually in the paint are more absorbing than the pigments in other colours, i.e., many ‘chemical’ or ‘metallic’ pigmented colours will dry shinier as they absorb less of the oil or painting medium, Titanium White for instance.
How do I Combat ‘Sinking’?
It would be virtually impossible to paint and get the levels of oil uniform across all your colour mixes so the easiest way to deal with the resulting ‘sinking’ is to use a technique known as ‘oiling out’ and this can be done using a variety of products. The most used is probably linseed oil; it is a relatively simple technique requiring just a piece of lint free, soft cloth, which you wrap around the end of your chosen digit (finger), dip into a small quantity of the oil, and using small circular movements gently rub into the sunken area of your painting until it takes on the same degree of sheen as the surrounding areas. Obviously, the paint must be dry before attempting this so I would suggest allowing at least seven days after your final brushstroke was applied, this will ensure you don’t loosen and smudge any paint. Personally, I use Safflower oil for ‘oiling out’ as it is less yellow than Linseed oil and therefore has less of an effect on pale colours.
There are other products that can be used to ‘oil out’ and I will only mention a few here so as not to over complicate the issue. You could use ‘Painting Medium’, poppy oil, walnut oil among others , Linseed, Safflower or your preparatory painting medium as I’ve already mentioned.
Varnishing with Wax
There is also the option of using a ‘Wax Varnish’ which has a few advantages over traditional picture varnishes. It can be applied using the same technique as for ‘oiling out’, rubbed on with a soft, lint free cloth once the painting is thoroughly touch dry for instance, seven days after finishing. Wax Varnish is a soft paste of Beeswax mixed with a mild spirit which evaporates leaving just the wax on the surface which can be left as a fairly matt finish or can be gently buffed to a satin finish or somewhere subtly in between according to preference. So, the advantages are, not having to wait 6 to 9 months before application, you can get a lovely, even, subtle finish and it can easily be removed should the need ever arise. I like and use the Winsor and Newton Oil Colour Wax Varnish which is purely a beeswax dissolved in white spirit and as I mentioned the spirit evaporates leaving only the beeswax on the painting surface and contains no resins so will never crack. MI