Dyes v. Pigments
Simply put, sunlight breaks down color. We’ve all seen that Coke can on the side of the road where the red is almost faded away. You may think it’s been there for some time, but it might not be as long as you think. Red color breaks down very quickly when exposed to the sun’s natural rays.
Color, in general, comes from two sources – dyes and pigments. Dyes add color to all types of materials, including printed products like Coke cans. Dyes do not perform well in the world of durable graphics. They degrade far too quickly in sunlight, no matter how you try to protect it. Pigments on the other hand are inorganic compounds insoluble in most liquids. Instead of naturally bonding to a material, as dyes do, pigments require a carrier. Pigments mixed with a carrier cure to form a thin film on the application surface.
Dyes
Dyes consist of organic compounds, soluble in a variety of liquids. Dyes impart color by absorbing into materials. They are very small in particle size. Commercial uses of dyes include clothing, leather, paper, wood, concrete and even food. Dyes, while versatile and safe, break down rapidly in the environment. UV light breaks down the chemistry that holds dye particles together. As they break apart, the color disappears.
Printing inks use dye because they are plentiful, safe and cheap. Many forms of printing don’t require longevity. If you’ve seen a full-color paper that’s been outside for a few days, it’s likely exposed area has lost much of its color. Colored furniture exposed to UV light will fade, even behind glass. Some dyes last longer than others, with those absorbing higher energy levels more susceptible to color change.
Dyes are wonderful ways to add color to a wide variety of objects but the particle sizes are too small and volatile to UV light. There is simply no way to protect them long term.
Pigments
Pigments don’t naturally bond to a material like dyes. They are insoluble in most liquids and require a carrier. The mixture of pigment inks and chemical carrier cure with UV light to form a thin film on the application surface.
Like dyes, pigments absorb the portion of light we don’t see, and reflect that which we do.
Pigments particles measure 1-2 Microns…many, many times larger than dyes. This makes them more able to reflect the color we want to see over long periods of time. Pigmented inks also hold up better when subject to other conditions, such as water and chemicals.
Pigments resist color degradation far better than dyes. The size and depth of the pigmentation matter a great deal. The outside of your car, for example, has a very dense layer of pigmentation. Along with specially engineered clear coats block UV rays (similar to a permanent sunscreen) before they get to the pigment. That’s why paint jobs on cars last so long.
Now that’s durability!
Want to learn if dyes or pigments are right for you? Click here!