Why is My Oil Painting Cracking?
Weeks after completing an oil painting, hair cracks may begin to form on the paint layer. The dry paint may start to flake off or become powdery to the touch. The upper layers can become brittle and dull. The reason for a cracking oil painting often goes back to improper preparation.
Why Cracks Appear in Oil Paint
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Reasons for a Cracking Oil Painting Rachel Shirley |
I believe oils are the most robust and durable of all art mediums and little attention is required. But a cracking oil painting is a problem the artist most fears. The cause of cracking often goes back to poor practices in oil painting and associated materials. How can the artist prevent cracks appearing in an oil painting?
Oil Painting Do’s and Don’ts
Investing a lot of time in an oil painting deserves the best art materials, or the time will be wasted. The following advice will help prevent the frustration of a cracking oil painting.
Never use substitute products for those designed for oil painting. Avoid household emulsions or cheap primers to prepare the painting support. These may not provide a sufficient barrier against the absorbent properties of canvas or board. The still‑absorbent support will suck the oil vehicle from the paint, causing brittleness and cracking. Stick to recommended oil painting primers such as Winsor & Newton or Daler Rowney. A good acrylic primer is fine for sketches or quick studies.
Do not use household or industrial solvents in place of artist mediums. They can affect pigment permanence, ruin brushes and emit strong odours. Use artist agents such as Sansador or artist varnishes.
Never combine mediums with varying drying rates, such as stand oil (slow drying) with alkyd mediums (fast drying). This causes stress in the paint layer and inevitable cracking. Stick to one medium per painting.
What is the Fat Over Lean Rule?
When working in layers, introduce a little more oil medium into your paint for upper layers. This “fat over lean” practice provides flexibility to the upper layers and prevents cracking.
Linseed oil is most commonly used, but stand oil, safflower oil or oil of spike lavender are also suitable. Stick to the same oil medium throughout a painting to avoid conflicting drying rates.
Proper Use of Oil Painting Products
Always read manufacturers’ instructions. Some products require specific preparation, such as rabbit skin glue or oil primers.
Never varnish an oil painting until it is thoroughly dry. If the paint is not dry, it may adhere to the varnish layer and “move” with it as it contracts, causing cracking. Later, when removing varnish for cleaning, some paint may come off with it.
Art Materials to Prevent Cracking in Oil Paint
Use proper artist products rather than industrial ones. Linseed oil, Sansador, stand oil or Turpenoid are suitable for thinning paint and cleaning brushes. Proper artist primer prevents the support from sucking oil from the paint. Artist’s gesso or acrylic polymer primer is most often used.
Any oily medium can be used for fat over lean, but linseed oil is most common. Artist varnishes are available from matt to gloss, provided the painting is fully dry (after six months or more). Oil paint is forgiving, and few artists encounter cracking even with shortcuts.
Cracking in oil paint is almost always linked to preparation: incompatible primers, conflicting mediums or ignoring fat‑over‑lean. By using proper materials and allowing the painting to cure fully before varnishing, the artist can maintain a stable, flexible surface and avoid future damage.
Comments
I had someone tell me to put it lightly on the back of the canvas. I also have a couple on wood.my e mail is ctedgell@ yahoo.com
You say you have paintings that are 125 to 150 years old. Have you thought of having them valued? They might be worth insuring or looking into. If there are no cracks in the paint layer, I would discourage preventative measures, with the view that if it is not broken, don’t fix it. Simply keep the paintings in a dry, cool place out of sunlight.
If you do see signs of cracking, I would recommend a professional restorer. Oiling out a very old oil painting is unlikely to cure cracking, as it is like trying to moisturise old skin. The wrinkles will remain and so will the cracks.
Also worth bearing in mind that the cracks might not be the paint layer itself, but the varnish. Some varnishes, such as Dammar creates a hard, inflexible layer that cannot tolerate temperature variations, which sets up stresses over the varnish. The paint, adhering to the varnish is likely to shift with the varnish.
Having said this, oil paintings are extremely robust and this problem seldom occurs.
A professional restorer would be able to establish the cause of the cracking. Removing the varnish would be the answer. But take care that the paint does not come off with the varnish. Again, I would strongly recommend going to a professional restorer for oil paintings that are old and possibly valuable.
Good luck!