Re: Why does construction paper fade in the sunlight?

Hi MJ, thanks for your question. It sounds like it might be an interesting science fair project. The reason paper fades is similar to the reason other materials, fabric for example, fade when they are exposed to sunlight. The situation is more complex than what is appropriate for this discussion but I will give you an introduction to the cause.

I answered a question about dyes earlier at MadSci. You can find the answer here: Why does construction paper fade in the sunlight?

In the answer there are a couple links about dyes and how they work.

Construction paper is given color by adding dyes to the paper during manufacture. These dyes are the primary culprits in the fading of the paper during exposure to sunlight. The energy in the sunlight allows the dyes to undergo a reaction that results in a less pronounced color.

Another contributing factor to the fading under sunlight could be a reaction with components of the tree that are leftover during the papermaking process (I have given a description of the papermaking process here: How is a paper make? What's the use of sodium hydroxide in this process?

If there is lignin left in the paper and the paper is exposed to sunlight, it will turn yellow, which is why newspaper turns yellow. The yellowing of the paper could compete with the ability of the dye produce a good result.