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Print Lighting: Update #1

Print lighting lux

Print lighting lux meter. Testing the lux measurement of the Halogen lamp of a long term print test.

It has been roughly nine months since the original “Print Lighting” blog where I started testing three 8×10 prints under different lighting; one under halogen, one with LED, and one with a CFL. From the outset, I had planned to give an update on the condition of the prints every month. Clearly I underestimated the quality of modern light jet prints and papers because until recently, there was no easily detectable difference between the test prints and the control that sits protected in a drawer. I have been blasting these prints with their respective form of lighting from eighteen inches away for at least ten hours a day since I started back in December! On the down side, this does not bode well to fill the website with more blog post updates, but on the upside for you, the consumer, this is a very good result. Before I get into how things are going on the testing front, I would like to share some important things I have learned in the time that this lightfastness print test has been running.

In the past nine months, and even more recently, I have not sat idly by waiting for a change in these prints. I strongly feel that it is important for the artist to know what they can about preserving the longevity of their work and passing on that knowledge to the buyer. I like to consider the print that a customer purchases as an investment, and I would like to see it last as long as possible. On my end, that starts with the right printing processes and the right mounting materials. Once you receive the print, I want you to have the right information to make informed decisions about where to hang your print and how you can safely light your print.

Intensity and Time

Without getting real technical, light is indiscriminate in the deterioration of artistic pieces. There are other factors that certainly lend to the lightfastness of a work, such as the medium the artist chooses, whether it is a photographic print or painting and the very pigments and paint the artist uses. How long the physical integrity of the work lasts in the light boils down to time and intensity.

First, let’s talk about UV or Ultraviolet light. UV is in the invisible light spectrum above visible light and is generally considered to be the most damaging. I think this is usually where the conversation stops and most people think that if their print is protected from UV with say, UV filtered glass or laminate, they don’t have to worry about much else. Even though UV is the most damaging, we have to consider visible light as well. We all want to see our beautiful works of art, and they are difficult to appreciate in the dark. It takes light for us to see them, but how much light becomes the balance between aesthetics and conservation.

To get more serious about preserving our works of art in the modern age, we also have to talk about lux, which is latin for light (surprise) and also defined as lumens per square meter or a measurement of light intensity over a given area. “Too technical,” you may say, “I just want to enjoy my print!” Well, what I think you should glean from this is that according to textile conservationists, there is a maximum number of lux (intensity) within a year (time) that your print can be exposed to while minimizing degradation. If you want the more technical version click here. According to the Northeast Document Conservation Center, the maximum cumulative amount of lux hours a light sensitive medium, such as a photograph should receive is 50,000 a year. To put that into perspective, if your print were to receive 100 lux of light for 5 hours a day, you could light it for 100 days.

The Print test

Print lighting distance

Showing the lighting of a 700 lumen LED light on a print from a distance of 10 ft.

Now that I have this information, I see that there are some variables that I did not account for from the start of this print test. Had I setup the test to measure equal intensity at each print, it would be more fair. These have been cooking for a while now so the only easy adjustment I can make is changing the distance of the print from the light. By changing the distance from the light source, even a little, the intensity changes dramatically. When the prints were all at the same distance, the halogen lamp showed twice the lux reading than the LED and four times the lux of the fluorescent. By moving the LED and fluorescent prints only a few inches toward the light, the lux readings became much more even across the board. For comparison, the recommended lux/year mentioned above is 50,000. ;The amount of lux that will be cast on the test prints accumulatively in a years time is just over 42 million! If I were going by the recommendation, 42 million lux should take 850 years, not one. Obviously, this is not what you would want to do in your home but for testing purposes, I am greatly speeding things up. So what should your lighting look like? Instead of leaving it to the buyer to do the math and buy a lux meter, let’s break down what the recommended lighting may look like in your home.

I could get into several variables that help determine how much light gets from the actual light source to the print but the two biggest factors are how much light is produced by the source (lumens) and what is the angle or “throw” that the light source is producing? Even though the test light sources are producing a very similar lumens number, the amount of light falling on the print or lux can be very different. The halogen light produces a much narrower angle than the fluorescent, therefore much more light is getting to the print. The distance between your light source and print can be the determining factor of how bright of a light you should purchase or how narrow/wide the angle of light should be.

Using the LED test light and a lux meter, I lit a 30″x40″ print, moving the light back until I reached 150 lux or less. With this particular 700 lumen LED light, I had to be ten feet away to reach 150 lux at the print. In this case, the LED light ends up illuminating the entire wall before I get to the light measurement needed revealing a much wider angle than I would care for at this distance. ;Using a much smaller halogen light at 485 lumens allowed me to reduce the distance to 6ft to reach a measurement of 150 lux or less while producing a much smaller angle of illumination. I would propose in most situations where the ceiling is of average height, such as the room this print is hanging in, it would only take about a 300 lumen bulb due to the distance the light fixture would most likely be. The only situation I could see having a brighter light is a vaulted or higher ceiling where the fixture may be much farther away. In cases of greater distance, the angle of light will become much more important and the more desirable a smaller angle of light or greater throw will be.

Print lighting bulb brightness options.

A couple of choices for print lighting, the 700 lumen LED ends up being overkill in nearly every situation. The 485 lumen halogen is at the top end of what I would consider using.

Results Update.

Finally let’s get to the print testing results update! Each 8×10 print has been holding up extremely well. Despite my best efforts to induce fading or significant color shift, they have been holding accurate color and saturation far better than expected. This is fantastic news if you are a buyer of modern prints. I don’t think that print longevity has ever been better and so far it shows. My comments on each light and print so far:

Halogen: Even though halogen lighting has been the standard for most museums for years due to its consistent warm light and very low UV output, I had my suspicions that it would fade the print due to the sheer output of heat, IR, and visible light, but so far the halogen-lit print is holding up extremely well. Comparing it to the control print, the detail remains the same and I do not see any glaring signs of fading. There is the slightest brown color cast, but it is very hard to see. Again, these prints are really being hit with a lifetime of light in a short amount of time and I must say that it is impressive. I have had to replace the halogen bulb once in nine months time, which is one disadvantage of this type of bulb compared to fluorescent or LED.

LED: The LED-lit print had my vote from the beginning as the one that would perform the best. I am not sure that I would say that it has done any better than the halogen print although instead of any color cast the print seems to have very slight fading noticeable in the sky compared to the control print. Without comparing both the halogen and LED print to a control print I don’t think I would be able to tell that there has been any deterioration at all. The LED light itself still provides the most pleasing light of the three, and the color of the print still “pops” with this light. It really makes the print stand out from the other two.

Fluorescent: The fluorescent-lit print seems to be the worst of the three. When lit, the quality of light is the least pleasing to me of the three and the print seems to have the most damage. Without a control print it would still be hard to detect the damage, but comparing it directly against the control, some fading and a reduction in contrast are noticeable, and there is a slight magenta color cast that is even more obvious when it is lit. I am surprised that the fluorescent-lit print is not much more faded given that fluorescents are known to produce the most UV of the three types of lighting, which makes me suspect there might be some UV filtering built into the light bulb itself. I will do some research on that.

All in all, I am extremely impressed with how all three prints are holding up. I plan on continuing this test at least through winter and will most likely post another update around the one year mark. Hopefully as time goes on, I will start to see more obvious and detectable signs of specific wear and be able to to report on that, but so far these prints are looking pretty bullet proof.

As always, if you have any questions, feel free to email me or post in the comments below.

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