Maybe someone has told you to choose a different color because your painting will “darken over time,” or you’ve just noticed that the oil painting you touched up above your fireplace isn’t the exact color you thought it was. You may be wondering if this was a result of your own doing or a natural occurrence.
Do Oil Paintings Darken Over Time? Yes, oil paintings darken over time due to the natural aging process and oxidation. Oxidation is a process that occurs when elements are exposed to air over long periods. Extra sunlight or exposure to the elements such as temperature and humidity may make a painting darken quicker.
The natural darkening of oil paintings can take years and years to actually happen; still, we play a role in how quickly painting ages. Below, I’ll tell you about some of the things that oil paintings naturally do over time and how we contribute to the process. Then, I’ll give you a few quick tips on supporting the longevity of your masterpieces.
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Why Do Oil Paintings Darken Over Time?
All things age, even oil paintings. Like humans, we can’t stop the aging process of an oil painting.
Oil paintings darken over time due to the absorbency of the ground and the type of light where the artwork is stored. The crystal structure of the oil paint pigments also grow larger over time and exposes more of their surface area to the oxidizing effect of light.
By over time, I mean that these things will be inevitable. However, the length of the time is greatly determined by the care placed on an object.
Over time can mean one year if the painting is stored over the fireplace directly across the window with the most sunlight and next to your humidifier. Additionally, suppose you’re constantly touching it and adding the natural oils from your hands to the paint. In that case, this could create a problem, too.
Museums have some of the oldest paintings ever created, and they hold up pretty well, though they have aged from their most authentic form. They have aged slowly, though, because proper care has been taken. But do notice that tempera walked so that oil painting could run; albeit very similar they have certain distinct properties
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Museums pay thousands and thousands of dollars to take proper precautions and slow the aging process. Though darkening led you to this article, let’s talk about all of the natural things that may happen to your oil painting over time.
Chemical Process of Darkening in Oil Paints
Oil paintings do darken over time, especially if exposed to high amounts of sunlight. The speed of this oxidation process, which is a natural part of aging, depends significantly on the source of the paints that make up the oil painting.
However, researchers found an interesting detail when using in-air plasma induced luminescence to investigate the darkening of masters Cezanne, Van Gogh, and Manet’s chrome yellows in their oil paintings.
They found that the darkening of the yellow was not so much the oxidation reaction itself but an altering of the crystalline properties of the paint pigments. The oil paints pigment crystals became larger over time, increasing their surface area to light oxidation and eventual darkening.
Some experts have also found that organic paints fade quicker in sunlight than synthetic dye. However, a genuinely noticeable and art-changing color change may take decades or even centuries.
Darkening may not be the only thing to happen, either. Colors may fade or become opaque as time goes on.
Lightfastness of Paintings
Besides natural darkening, some paints are just made to look different over time. You should be able to see a lightfastness rating on each bottle of oil paint. Try to go for the paints with higher star ratings if you don’t want a lot of change.
Some might avoid these paints because they tend to be more expensive, but they’ll definitely be worth it if you don’t want them to age.
The minerals contained in your particular oil paint may also make your colors more prone to darkening. For example, Rose Madder, Indigo, and other pigments made from organic dyes are prone to fading in the light, while Chrome Yellow is prone to darkening.
Environmental contaminants such as hydrogen sulfide may also darken your oil paints when exposed to their presence.
Protecting Your Oil Paintings From Darkening
Have longevity in mind from the moment you begin purchasing your supplies to the moment you are measuring out the best spot on the wall. Proper storage is key, as well as choosing an area with controlled temperature and humidity if the painting is of value.
Hanging your painting above a fireplace or heating vent will likely speed up the oxidation (and aging) process, as will putting your oil painting outside or in a sunny spot. Additionally, using low-quality oil paints or thinning your paints with mediums may also hasten the darkening process.
You can varnish a painting to increase its longevity, but this step is to proceed with caution. Varnishing should only occur after the painting has completely dried. You may assume that your painting is dry as long as it’s not wet to the touch, but this isn’t actually the case.
Typically, paintings can take up to six months to dry thoroughly! So, keep this in mind before applying any sealant or varnishes.
Final Words
The oxidation process is unavoidable and can cause oil paintings to darken over time. You can’t do much about the natural process of aging, but there are things you can do to help slow it down. Make sure to hang oil paintings in a good spot in your house that keeps them away from sunlight, high temperature, and excess humidity.
Additionally, if you are an artist, try to use high-quality oil paint and canvas. Using primer beforehand and then sealing your painting when it’s all dry can significantly affect the piece’s longevity.
Sources
- Live About: Should an Oil Painting be Framed Under Glass?
- Diploma Frame: Damaging Elements to Framed Documents and Artwork
- Indiana Public Media: Changing Oil Paintings
- Royal Museums Greenwich: The Conservation Process
- Inside Science: Why Do Yellow Pigments Darken Over Time?