How to Ensure the Longevity of your Artwork
What you don't know might hurt you! by Susan Avis Murphy
By longevity, I mean the durability of the entire artwork over time. Whether the pigments are lightfast, whether the support of canvas or paper is acid-free, and whether the framing is archival. An original watercolor can remain fresh and safe for hundreds of years as long as these criteria are met. A watercolor can last without damage as long or longer than most oil paintings if it is created and kept under the right conditions. Let me explain.
There is a national organization called the ASTM, or American Society for Testing and Materials. The ASTM conducts lightfastness ratings for artist pigments, and Rose Madder Genuine only gets a rating of III. Professional artists should only be using pigments with an ASTM rating or I or II. For my own artwork, I only use totally permanent pigments. Also I always instruct my students to do the same and put a big emphasis on this...
Take a look at this interesting little chart I created 20 years ago. This is a segment of a much larger chart I made to test the lightfastness of all the pigments I currently owned. Strips were painted, labeled, and then half covered with matboard and placed in a bright window for two years (about 3 hours sunlight daily). Look what happened to Purple Lake, Rose Madder, and especially Scarlet Lake! Can you believe it?!! After this, I threw those tubes of paint away!
Once I had a customer tell me about a painting his mother had bought, with red flowers in it. After two years, the red flowers had disappeared! Perhaps the artist had used Scarlet Lake!!
Nowadays I continue to test my pigments just to be safe, and also as way to convince my students of the necessity to pay careful attention to the lightfastness of their pigments. I have devised (and sell here at ARThouse) a special "Watercolor Test Sheet" that can be filled in with all the pigments an artist owns in order to determine their various properties, including lightfastness. Here is what the sheet looks like before the artist has painted in the colors:
Here is an example of the sheet after the blues have been painted:
Here is one row of the sheet enlarged:
Let me explain how the chart works. Each pigment is used for one row, and painted on with water at a medium value. The first circle is meant to show the general characteristics of the pigment, especially granularity (cobalt blue does not granulate very much). The second circle is used to show the staining vs. lifting characteristics of the pigment: the circle is painted and then dried, and then the left half is covered with drafting tape while the right half is scrubbed off (using a stencil brush) with a fixed amount of water and pressure; this shows how easily the paint can be removed and whether it is a staining color. The third circle is sprinkled with table salt while it is still wet, to show the degree of salt effect achievable. The fourth circle contains a little black image so that we can see the degree of transparency vs. opacity of the paint. And last but not least, the rectangle is used to test the lightfastness of the paint. One half of this square is covered with dark paper and the sheet is hung in a bright window for about three months to two years.
Here is what the larger version looks like with colors painted in and black strips stapled over the rectangular square for the lightfastness test:
I have found these Watercolor Test Sheets to be extremely useful while I paint. I use them mainly for choosing colors that I know will be liftable and not stain the paper, one of my main criteria for desirability of a watercolor pigment! I also use them to remind myself of colors I seldom use. And most importantly, I use them to ensure that my pigments are lightfast. Any color that fades is banished from my palette forever!
There are several commonly used pigments that I would be wary of, if I were you. In the Winsor & Newton line, be careful of Rose Madder Genuine and Alizarin Crimson, which get a "B" grade using the company's own rating system, equivalent to a III in ASTM terms. These colors will change with time. In the Holbein line, be wary of their four colors beginning with the words "Bright" or "Brilliant": Bright Violet, Bright Rose, Brlliant Pink, and Brilliant Orange. The company admits that these colors contain a flourescent dye, which glows upon exposure to light and makes the pigment look brighter. The problem with this is that the flourescence involves a chemical reaction which decays over time, rendering the pigment much less bright than it was originally!
As an artist or also an art collector, I would be very wary of collage materials whose sources are questionable. For example, magazine paper used as collage, photographs, colored tissue paper, or rice papers from unreliable sources could all be extremely fugitive. The colors you love in that painting when you buy it may not be there two years later! Also many of these materials are not acid-free and will become brittle and decay with time. Additionally, the glue used may yellow and suddenly show up like a sore thumb! Ask the artist if they are confident in the longevity of their materials before buying. I hate to say this, but hopefully it will make them more aware and more responsible...
Is there anything you can do to preserve the artwork's colors if you are not sure about their lightfastness? Yes, you can frame the picture under "UV glass" or Museum Glass (made by TruVue). Visit the picture framing section of my website for a discussion of these types of glass: (link). Museum Glass is a wonderful product, because not only will it protect the picture from ultraviolet radiation, but also this glass has an anti-reflective coating (an optical coating like the type put on lenses) that makes the glass seem almost invisible.
The bottom line is that artists need to be very careful about the pigments they use, and art buyers need to be careful that the artists they buy from are using lightfast paints! Here I can say with absolute confidence that the pigments I have been using for the last 20 years are truly lightfast and will stand the test of time... I thank my lucky stars that I can say this!
For artists reading this, there is an excellent book on the subject, The Michael Wilcox Guide to the Finest Watercolor Paints by Michael Wilcox (latest version is around c2002). Buy this book and consider it your Bible.
Susan Murphy, ARThouse, May 22, 2012