It is not uncommon to see pictures of old oil paintings that look great from afar, but upon closer inspection, you notice that the layers of paint have cracked or become distorted. As an artist, so much love, time and devotion are poured into every work of art, so it can be devastating to discover that a piece of art has cracked. What can be done to keep an oil painting from cracking?
How To Keep An Oil Painting From Cracking?
There are three common rules of oil paint that guide artists to prevent their work from cracking. These three rules are the ‘fat over lean’ rule, the ‘thick over thin’ rule, and the ‘slow drying over fast drying oil paint’ rule. By adhering to these oil paint guidelines, it will create a more flexible artwork that eliminates most of the threat of cracking.
It is also important to consider the preparation and materials used with your oil painting. Proper canvas preparation and final finish can greatly impact the longevity of your work. I High-quality products such as linseed oil, artist’s gesso, or acrylic polymer primer are also recommended for best results.
Now let’s explore each of these rules, preparation procedures, and products in more detail.
- Fat Over Lean Rule
Due to the nature of oil paint, it is recommended that you add a medium to your colour pigments to create flexibility in your artwork and ensure better adherence to your paint. Ideally, each new layer of paint is more flexible than the layer preceding it. By increasing the flexibility of the top layers, your painting will be less likely to crack over time.
Drying oils speed up the drying process of your oil painting by oxidising and hardening over time. Volatile oils, such as turpentine, evaporate. This is why it is important to choose your medium wisely and remain consistent throughout your painting. This effect is achieved by adding more oil medium to each new layer of paint.
‘Fat’ layers of paint are those that contain more drying oils and go over the layers of paint with less drying oil or ‘lean’ layers of paint. This formula is helpful when mixing your oil paint and mediums together.
- 1st Layer of Oil Paint: Very dry – mostly solvents, little colour pigment
- 2nd Layer of Oil Paint: Dry – lots of solvents, more colour pigment
- 3rd Layer of Oil Paint: Medium – little solvents, some drying oil, some colour pigment
- 4th Layer of Oil Paint: Oily – little or no solvents, drying oil, colour pigment
(NB. In all layers, keep the solvent ratio at less than 50% to paint).
Linseed oil is the most common medium used; however great alternatives include stand oil and safflower oil. Whichever you choose to work with, it is vital to remain consistent throughout your painting to avoid conflicting drying times.
- Thick Over Thin Rule
Similarly, it is recommended that each new level of paint added is thicker than the layer before it. Thin layers of paint dry quicker than thicker layers so this ensures that your artwork dries correctly, especially at the bottom layers, and prevents cracking.
- Slow Drying over Fast Drying Oil Paint
Whether you prefer fast drying oil paints or slow drying oil paints, it is important to remain consistent throughout your artwork. It is advised against mixing mediums with different drying rates as it causes stress in the painting as it dries. If you do have to mix the two different paints, layer the fast drying oil paint at the bottom and the slow drying paint over the top. Make sure you are giving each layer of paint ample drying time as rushing and painting over wet paint will ruin your artwork.
It is important to use high-quality products specifically designed for art and oil paintings. Never substitute household items or cheap primers for high-quality supplies as they may not provide enough of a barrier against the absorbent qualities of the canvas. This will allow the oils to be absorbed from the paint, leaving it brittle and cracked. In addition to the physical properties that occur on your artwork, household items not only affect the pigments of the oil paint, but they can ruin your paintbrushes, and emit potentially harmful odours or residues.
Once your oil painting is complete, it is important to allow ample time for drying before applying the varnish to seal and protect your oil painting. It is recommended to wait six months before applying varnish to ensure all the layers of paint have dried completely.
If varnish is applied before the oil paint is adequately dry, the paint could stick to the layer of varnish and ‘move’ with the varnish as it dries. This will also cause cracking as the varnish dries. Another issue that occurs with oil paint that adheres to the varnish is when the varnish is removed during a cleaning and restoration session. When the varnish is removed, some of the oil paint will be removed along with the varnish.
Restoring A Cracked Painting
Despite our best efforts, fluctuating temperature and humidity levels may still result in a cracks. Does that mean it is ruined, or can it be restored?
While it is impossible to restore cracked paintings to their original state, it is possible to reduce the appearance of cracks. Depending on the nature of the artwork, it may be recommended to take it to a professional art restoration centre.
If you wish to repair the artwork yourself, the process involves strengthening the surface with a beeswax and damar resin mixture, which will also prevent further deterioration of the oil painting and glues the paint to a stronger base.
While it may seem like an overwhelming task to ensure your oil painting doesn’t crack, if you follow the guidelines, you shouldn’t have any problems.
Simply use good quality products on your oil paintings, remain consistent with the products used, and allow ample drying time in between each layer of oil paint to prevent any crack in your artwork. Most importantly, have fun and get creative!