Yes, sunlight can and will cause the pigments in watercolour paintings to fade over time.
But it is not only sunlight that can cause this. Fluorescent light bulbs have the same concentration of UV as is found in a natural sunlight (this is the reason why most art museums avoid using them), and exposing watercolour paintings to prolonged light of either kind can and will cause the beautiful colours of the painting to tarnish over time, becoming dull, washed out, and eventually, difficult to make out altogether.
The beautiful fragility of watercolour paints extends not only to the process of painting, but also to the preservation of watercolours long-term. Being painted primarily on paper, or even on silks in some cases, completed watercolour paintings are, unfortunately, at great risk of coming to harm through neglect, accident, or even through simply not knowing the many outside forces that can diminish the lifespan of a watercolour painting.
Smoke damage, for example, can permanently affect a watercolour painting, as well as drastic changes in the environment it is being kept in, such as too much light, or the wrong kind of light. With this all being as it is, the prospect of trying to maintain a watercolour painting without it getting damaged may seem daunting, but with the right information and the correct actions being taken, there is no reason why your watercolour paintings’ integrity should suffer in any way throughout the ages to come.
How To Stop Watercolour Paintings From Fading?
Starting off with the most important takeaway point: more important than any frame, watercolour paintings fair best when kept behind glass. This can be using a wooden frame, or simply by carefully sandwiching the paper between two planes of glass, but a glass front will protect the watercolour painting from most of its most present dangers.
For one, any exposure to water or access moisture will cause the pigment to reconstitute, effectively becoming free-flowing pain again. This can have any multitude of effects, from warping the paper surface to causing fuzziness in the details of the painting, to even causing the paint to run if the damage is advanced far enough. A good glass front will protect the watercolour painting from any exposure to unneeded moisture, as well as being a second layer of protection from other elements, including smoke, or rapid atmospheric changes.
Before hanging up your watercolour painting, I recommend taking a long tour of the place you’d like to keep it, and to consider the sources of light that will be directed at it. While nobody wants to exhibit their painting in full darkness, you’d like to prevent it having a window pointed at it for the longest, most sunlight-filled hours of the day, and to make sure that any lights that the painting is exposed to have non-UV light bulbs, in order to prevent a similar effect.
Something else to consider when arranging for your watercolour painting to be hung up in a way that preserves the painting for years to come is the frame itself, in addition to the location and light sources that the painting is exposed to. As with all painting, watercolours stand much to benefit from archival framing techniques, which employ materials that do not interact with any of the materials that the painting is made up from. The pins, wooden frame, and mat board should all be made from nonreactive sources that do not affect the paper of the painting, especially over a long period of time, and can be taken apart and replaced with time without at all risking the integrity of either pigment or paper.
For example, the mat backing of the frame should only ever be made using cotton or linen, preferably those that do not contain any acid in their preparation, as it can damage the paper. Similarly you’ll want to avoid adhesion at all costs, since most glues are non-archival, and, especially when it comes the fragile materials of a watercolour painting, cannot be removed without causing damage to the painting, which could be necessary in the future, should the frame start to break down or become damaged in any way. Using archival framing of high quality is a simple measure that saves a lot of work in the long run.
As previously stated, one of the best ways to prevent sunlight from rapidly fading your watercolour paintings, which can happen over a matter of a few months if left exposed and unprotected, is to keep it behind a pane of glass. However, not all panes of glass are the same, and some forms of glass serve much greater protection than others.
For example, a regular glass frame shields your watercolour painting from a little over 50% of harmful UV rays, which is still a great deal. But more modern techniques, investing in other forms of glass, like conservation glass, glass with a layer of protective arcylic, and museum glass, can reflect as much as 99% of UV, and make it so you can present your painting in full light with minimal fading.
When it comes to selecting which of the options is right for you, the pricing is a major component, as well as the different ways that the glass filters or reflects light and the effect that it has on your painting. Conservation glass has a layer that reflects glass outwards, which protects your painting effectively, but is also has a slightly opaque, greenish tone, which obfuscates the original colours of your painting. More expensive museum glass functions by filtering the light through many small layers of glass, meaning that less than 1% of the UV reaches down to the painting below, and it has the additional effect of illuminating your painting, because the natural light is allowed to filter through to the surface below, with the harmful UV rays unable to effect the paper of the pigments.
Ultimately, however the choice is yours, and with the right techniques and equipment, you should be able to exhibit your watercolour paintings for many years to come without compromising the longevity of the painting itself. After all, art is meant to be appreciated.