However there is an important exception and that is when an old painting is suffering from discoloured or yellowing of the varnish layer.
Drying oil painting in the sun.
A couple of other things to think about that.
Oil paintings need daylight.
Stir it periodically to hasten drying.
This will make your paintings dry in a day or two compared to a week.
In general i agree with what has been said so far its not a good idea to leave an oil painting in full sunlight for an extended period of time this will affect certain pigments.
This layer of paint dries quickly within 24 hours.
As you may have guessed from the prior answers drying an oil painting in the sun is the wrong thing to do.
Two paint using thin layers and washes which will dry reasonably quickly.
Not direct sunlight due to fading and too much darkness will cause it to yellow.
I typically find this is not such a good method as the paint dries too.
Pour some oil about an inch into a wide dish cover it with a propped up lid i e.
After that i embrace the slow drying time of oil paint rather than try to avoid it.
Sun thickened linseed oil is a created by exposing the oil to the sun to create a thick syrupy somewhat bleached oil with similar brushing qualities to stand oil.
Bugs will get stuck to it.
Use alkyd white instead of normal white to mix with your oil paints.
Combine linseed oil with the paint on your palette.
To speed up the drying time you can turn on a.
Buy some commercial paint hardener or dryer to dry paint in a hurry.
Since linseed oil dries faster than other kinds of oil mixing a little extra linseed oil with the paint on your palette can help speed the drying time of your painting.
Use an alkyd medium with your colors.
How to make your oil paintings dry quickly.
One leave the painting to dry in a well ventilated open area where air circulates a fan helps.
To minimize debris getting in but so that the air can flow through.
Avoid extreme heat like hairdryers as this will only make the process worse.
When i start an oil painting i will usually thin the paint using odorless solvent so that it becomes a thin wash with a watercolor like consistency.
Pour paint from a full can into other cans or containers a little in each so it dries quickly.
This process is demonstrated in the painting below.
The sun will take away the color.