Oiling Out: How to restore depth and colour to your oil paintings

If you’ve noticed dull, patchy areas in your painting, this guide will walk you through what oiling out is, why it happens, and how to do it correctly.

What is oiling out?

Over time, an oil painting can lose its vibrancy, with colours appearing flat or muted. This effect, called sinking in, occurs when the top layer of oil is absorbed by the underlying paint layers.

Oiling out is the process of reintroducing oil to these sunken areas, restoring richness, depth, and luminosity to the surface.

What does oiling out achieve?

Oiling out:

• Revives colour and increases saturation
• Restores a consistent surface sheen
• Allows you to continue painting immediately or once the layer has dried

How to oil out a painting

The simplest method is to use a mixture of stand oil and Sansodor (Winsor & Newton’s low-odour solvent).

Step 1: Mix your medium

• Start with one part stand oil to four parts Sansodor.
• If your paint already contains added oil, increase the proportion of stand oil to maintain the fat over lean principle.

Step 2: Apply the mixture

• Blend thoroughly before use, ensuring the oil and Sansodor are completely combined.
• With a soft brush, apply a thin, even layer of the mixture across the surface.
• You’ll notice that dull areas will absorb the mixture and instantly regain depth; and excess medium will simply sits on the surface.

Step 3: Remove the excess

• Using a lint-free cloth, gently wipe away any unabsorbed medium.
• Store the remainder in a clearly labelled jar—you’ll need it to thin your paint in subsequent layers to keep following the fat over lean rule.

Why do oil paintings become dull?

Several factors can cause sinking in:

• Absorbent or poorly primed surfaces: Without priming the surface correctly, paint sinks into the weave of the canvas.
• Overuse of solvent: Thinning early layers with too much solvent makes them pull oil from upper layers.
• Ignoring the fat over lean rule: Each layer should contain slightly more oil than the one beneath it.
• Mixed drying rates: Paints that dry at different speeds can create uneven absorption.

Frequently Asked Questions

Should I always oil out before varnishing?

No. Only oil out if you see areas of dullness.

Can I oil out after varnishing?

No. The varnish would need to be removed first.

Is sinking in a problem with alla prima painting?

Yes, it can be. Even though alla prima (wet-on-wet) often blends into a single layer, any paint applied on top of another—wet or dry—creates a layer, so the fat over lean principle still applies.

What is the difference between sinking and shrinking?

• Sinking = loss of oil in upper layers, resulting in dull patches.
• Shrinking = upper layers drying faster than those beneath, causing wrinkling or cracking, especially if impasto is used too thickly.

Alternatives for oiling out

• Artists’ Painting Medium: Apply sparingly with a cloth for localised dull spots. Wipe away residue and repeat if necessary.
• Thickened Linseed Oil (diluted 50% with white spirit): A faster-drying option.
• Artists’ Retouching Varnish: Useful for isolated dull areas. This ready-to-use product can be brushed on directly; after five minutes, the surface is ready for further work.

Final Thoughts

Oiling out is a quick, effective solution to one of oil painting’s most common issues. By restoring depth and richness, it not only improves the visual impact of your work but also ensures a sound foundation for further painting.