Quick answer: Oiling out a painting means rubbing a very thin layer of oil or oil-based medium over dull, matte patches of a dry or touch-dry oil painting to restore their depth and color before you continue painting or varnishing. Those dull areas, called “sinking in,” happen when a lower layer absorbs oil from the paint above. Apply a few drops with a lint-free cloth, wipe off nearly all of it, and let it dry before the next step.
What is oiling out a painting, and why do painters bother? Anyone who has worked in oils for a while knows the frustration: you return to a painting after a few days and some areas have gone flat and chalky, especially the darks. The colors look wrong, edges seem to vanish, and it becomes hard to judge what to paint next. Oiling out is the traditional fix for that problem, and it also prepares the surface so the next layer bonds well.
Below you will find what causes sinking in, the step-by-step method, what to use, how much is too much, and how oiling out differs from varnishing. If you are still putting together your kit, our overview of essential oil painting supplies covers the mediums, rags and brushes this technique relies on.
Why Oil Paintings Go Dull: Sinking In
Oil paint dries as its oil reacts with oxygen and forms a solid film. When you paint over an absorbent layer, that lower layer can pull some oil out of the fresh paint before it cures. The new layer is left with less oil binding the pigment, so its surface becomes rough at a microscopic level and scatters light. That scattered light makes the area look pale, matte and lifeless.
Common causes include:
- Absorbent grounds. Some gessos and grounds, especially chalky ones, drink oil from the first layers.
- Lean underlayers. Underpaintings thinned heavily with solvent are porous and absorb oil from paint above.
- Certain pigments. Earth colors and some darks are especially prone to sinking, because they dry quickly and can be porous.
- Uneven medium use. Areas painted with more solvent or less oil than their neighbors dry with a different sheen.
- Thin paint over thick paint. Thin passages over a more absorbent area can look patchy next to thicker strokes.
Sinking in is not a sign the paint is ruined. The color is still there. It just needs its optical depth restored.
What Oiling Out Does
When you oil out, you add a tiny amount of oil back to the surface. That oil fills the microscopic roughness, light passes through instead of scattering, and the color looks as rich as it did when it was wet. It also:
- Shows you true values and colors so you can match new paint accurately.
- Evens out the sheen across the painting.
- Gives the next layer a slightly receptive surface to bond to.
- Prepares a painting for varnishing by reducing patchy absorption.
How to Oil Out an Oil Painting: Step by Step
- Wait until the surface is touch-dry. The paint should not lift or smear when you touch it gently. For thin layers this may be a few days; thicker passages take longer. Oiling out wet paint simply smears it.
- Set the painting upright or flat with good light. Raking light from the side helps you see which areas are dull. Many painters work with the canvas upright on a stable easel; if you need something steadier, the review of easels for oil painting compares sturdy studio and tabletop options.
- Dust the surface. Brush or wipe off any dust, hairs or lint so they do not get trapped.
- Choose your oiling-out medium. Options are covered in the next section. Pour a small amount, a few drops to half a teaspoon for a medium-sized canvas, into a clean dish.
- Apply sparingly. Dip a lint-free cotton rag, a soft brush or a clean fingertip in a nitrile glove into the medium. Rub it over the dull areas in small circles, or across the whole painting if you want an even surface.
- Wipe off almost everything. With a clean part of the rag, wipe the surface until it looks barely wet. The goal is a film so thin it is almost invisible. Any visible pooling or drips is too much.
- Check from an angle. Look across the surface against the light. It should have an even, slight sheen without thick glossy patches.
- Paint into it or let it dry. Some painters immediately paint wet-into-the-oiled surface, which can help new strokes blend. Others let the oiled layer dry for a day or more and then continue. Both are common.
- Repeat only if needed. If areas sink again after the next layer, you can oil out again, but keep each application very thin.
- Dispose of rags safely. Oil-soaked rags can heat up as the oil cures. Store them in a closed metal container with water or lay them flat to dry outdoors before throwing them away, following local rules.
What to Use for Oiling Out
| Option | How it behaves | Advantages | Drawbacks |
|---|---|---|---|
| Refined linseed oil, thinned slightly with odorless mineral spirits | Classic choice; spreads easily | Simple, inexpensive, compatible with most oil paint | Slow drying; too much can yellow or wrinkle |
| The same medium used in your paint | Matches your painting system | Consistent sheen and drying | Depends on what that medium is |
| Alkyd-based painting medium | Dries faster | Lets you continue painting sooner | Can become tacky quickly; work fast |
| Commercial retouch varnish | Thin, temporary resin layer | Restores color and protects temporarily | A varnish, not oil; different handling rules |
A commonly cited homemade mix is roughly equal parts linseed oil and odorless mineral spirits, though many painters prefer a higher oil proportion so the layer stays fat enough for later layers. Whatever you choose, the critical factor is not the recipe but the thinness of the application.
Oiling Out vs Retouch Varnish vs Final Varnish
| Feature | Oiling out | Retouch varnish | Final varnish |
|---|---|---|---|
| Material | Oil or oil medium | Dilute resin in solvent | Resin or synthetic varnish |
| When | During painting, between layers | During painting or before final varnish | After the painting is fully dry |
| Becomes part of the paint? | Yes, permanently | Thin temporary layer | No, a separate removable coat |
| Purpose | Restore depth, help adhesion | Even sheen, temporary protection | Long-term protection and unified finish |
| Removable? | No | Partially, with care | Usually yes, with the right solvent |
The key difference is permanence. Oil becomes part of the paint film; varnish sits on top as a protective, removable layer. That is why oiling out should be thin and why it does not replace a proper final varnish.
How Much Is Too Much?
Over-oiling is the main risk of the technique. A thick oil layer can:
- Stay tacky for days or weeks
- Wrinkle as it cures
- Yellow over time, especially over light colors
- Attract dust and lint while wet
- Make the surface too slick for the next layer to grip
A good rule of thumb: after wiping, you should be able to touch the surface lightly and feel only a faint slickness. If oil comes off on your glove, wipe more.
When to Oil Out
Before continuing a session
The most common moment. If you return to a painting and cannot judge colors because areas have sunk, oiling out restores what you painted so you can match it.
Before final varnishing
Patchy absorption can make a final varnish look uneven. A light oiling out several weeks or months before varnishing, once fully dry, can even the surface. Some painters prefer a retouch varnish for this step instead.
After a long break
If a painting has sat for months and you want to rework it, oiling out helps fresh paint bond to the cured surface. A light sanding of high ridges may also help.
When not to oil out
- On wet paint: it will smear.
- On alla prima paintings finished in one session: they usually dry with an even sheen.
- On acrylic paintings: use acrylic mediums or varnish instead.
- On very old or valuable paintings: that is a conservation question, not a studio technique.
Preventing Sinking In
Oiling out treats the symptom; a few habits reduce how often you need it.
- Seal very absorbent grounds. An extra coat of ground or a thin layer of acrylic medium makes a less absorbent base.
- Avoid excessively lean layers. Use solvent mainly for the first thin layer, then add a little medium.
- Be consistent with medium. Using the same mix across an area dries to a more even sheen.
- Add a touch of medium to sink-prone colors. Darks and earth pigments often benefit from a little extra oil.
- Follow fat over lean. Each layer slightly richer in oil than the last tends to reduce absorption from above.
Troubleshooting After Oiling Out
The surface is still tacky days later
Too much oil was left on, or the room is cold and dark. Move the painting to a warm, well-lit spot with good airflow; oil cures faster with light and warmth. Avoid adding more paint until it firms up.
Some areas still look dull
Very absorbent patches may take up the first application completely. Wait until it is dry to the touch and repeat with another very thin wipe on those spots only.
Lint or hairs are stuck in the surface
Lift them with the tip of a clean palette knife or tweezers while the layer is still soft. Next time, use a lint-free cotton cloth rather than a paper towel.
New paint slides around on the oiled area
The layer is too slick. Blot it with a clean rag, or wait for it to set slightly before painting. A thinner application next time gives brushstrokes more grip.
Glossy patches next to matte ones
The oil was applied unevenly. Once everything is dry, a light, even oiling out over the whole painting, or a retouch varnish, usually unifies the sheen.
Common Mistakes
- Pouring medium directly onto the canvas instead of applying it with a rag
- Leaving a visible wet layer rather than wiping it nearly dry
- Oiling out paint that is still soft
- Using a linty paper towel that leaves fibers behind
- Repeating oiling out after every layer when it is not needed
- Treating oiling out as a substitute for final varnish
Tips by Experience Level
Beginners
Keep it simple: a small bottle of refined linseed oil, a little odorless mineral spirits and a cotton rag. Use it only when areas look clearly dull. Practice on a study first to learn how little you need.
Intermediate painters
Notice which pigments and grounds sink most in your work and adjust your mixes to reduce it. Try painting directly into a freshly oiled surface to see how it affects blending.
Advanced painters
Match the oiling-out medium to your painting system, track drying times on test panels, and keep notes on what was applied to each painting. Those notes help future conservators and keep your layering consistent.
FAQs
How do you oil out an oil painting?
Once the surface is touch-dry, rub a few drops of oil or medium over dull areas with a lint-free rag, then wipe off nearly all of it. Continue painting into it or let it dry first.
What oil is best for oiling out?
Refined linseed oil, often thinned a little with odorless mineral spirits, is the traditional choice. Using the same medium you paint with keeps the system consistent.
How long after oiling out can I paint?
You can paint immediately into the thin oiled layer or wait until it is dry to the touch, usually a day or more depending on the medium.
Does oiling out replace varnish?
No. Oiling out becomes part of the paint layer. A final varnish is a separate, removable protective coat applied once the painting is fully dry.
Why are the dark colors in my oil painting dull?
Darks and earth colors are especially prone to sinking in, where the layer below absorbs oil. Oiling out restores them, and adding a little medium to those colors can help prevent it.
Can you oil out an acrylic painting?
No. Acrylic does not use oil as a binder. Use an acrylic gloss or satin medium, or an acrylic varnish, to even the sheen.
Final Thoughts
Oiling out is a small technique with a big effect: a few drops, wiped almost dry, can bring a flat painting back to life and help the next layer bond. Use it only when you need it, keep it thin, and pair it with good layering habits. For the oils, mediums and lint-free rags that make it easy, our roundup of the best oil painting supplies for artists is a practical place to stock up.
