We all know that long term exposure to ultraviolet light has a detrimental effect on LEGO bricks. Somewhere in your collection are white pieces that could be mistaken for tan, a blue part that has faded and has an off tint, and some old grey that is a little more yellow than when it was new. But how fast does it set in? Is a month on display in a room with windows enough to cause noticeable damage? Let’s sacrifice some LEGO for science to find out.
Some notes on Red-Green-Blue Values
After analyzing the color values, I figured we need to establish a common language before we dive into the results. Looking at the numbers, 0,0,0 is pure Black and 255,255,255 is pure White. Any combination of three values that are roughly equal are going to be in the Black-Grey-White continuum.
Secondary colors are Yellow (Red + Green), Magenta (Red + Blue), and Cyan (Blue + Green).So a clear indication of yellowing would be an increase in the Red and Green values while Blue stays constant or decreases.
Orange and Purple are tertiary colors which is one of the reasons these colors can be difficult to create digitally, print, and occasionally just look off in digital photos.
For the Blue Mario Plate, the Blue and Green lines stay fairly flat there is some wiggle and difference between the control and test objects but nothing I would call significant. Both white elements stay with in a band of 35 color value points (CVP—I made that up!). As the values track with each other week to week and there is no large increase in any value over the others I’d say the fluctuation is due to lighting differences in the photographs.
The trans clear shows that the control had a slightly lower blue value than the experimental piece. (Which supports something I should have noticed in the beginning, and will discuss more in a moment.) Due to the color variation from thickness changes this was a very difficult piece to measure. Also in measuring a clear piece, I was really measuring the paper behind it and the amount that the clear piece distorted that color. That said with the exception of the dark September 17th measurements this part was fairly consistent. Light blueish grey was super consistent, no one week registered more than 10 CVP apart between Red, Green and Blue! The drop off for the final measurement was a lighting issue.
So the data interpretation suggests that seven weeks of exposure has minimal effect on the color of the brick.However as the windows in the house were installed before I purchased it I cannot conclusively say that they received true UV exposure. So that might be an unknown factor.
So here is where I admit that my scientific rigor could have been a lot better!I wanted to photograph the test samples each Wednesday evening for at least a month to six weeks. Well that didn’t work out exactly—data was taken on three Wednesdays, a Thursday, and two Fridays over the seven weeks from Aug 18 – Oct 6.To further complicate things some of my photo taking was not as consistent as I thought it was. I should have set up a more dedicated set up, gotten more identical pictures, and marked reference points on the bricks for measurements.
Also late in the experiment I noticed that the trans clear Technic beam used in the control set had a slight yellow tint to it and the experimental piece was more clear. (The higher Red and Green values I mentioned above.) I’m not sure how I didn’t see this until the end!So now that I’ve poked holes in the sloppiness of my methodology (think I’ve disqualified myself for even an Ig Nobel Prize).
So what was done right?The test panel was located in the same position on the window sill each time.The control was kept away from any sunlight in my basem*nt LEGO area.Photographs always have the control on the left and the experimental piece on the right.
Conclusions
So what can we conclude? Well, I’m calling my test inconclusive as I did not control for the potential that my windows have an unknown UV coating. Placing samples outside may better test the specimens, but caution will have to be taken to protect the samples form dirt, pollen, wildlife and other hazards of the outdoors.A small clear enclosure would likely suffice, a screened in patio, or similar structure could be used.This could make a great science fair experiment, but it does have a bit of longer time span—longer than anything I did in school.
Given my experience with other plastics (toys, totes, flower pots, etc. that have been left outside year round) I still believe that the UV breakdown is a long term processes.This is further supported by the fact that it is well known that The LEGO Group does significant environmental and quality testing on all elements, and I would think that color fastness would be addressed in that testing in some way.So my final thoughts are that short term displays where bricks get exposed to direct sunlight are likely not something to fret about in terms of yellowing, but anything over several months and I would be cautious, especially if the build contains older bricks.
Onto the next brick experiment!
