What Is Lightfastness?

Lightfastness or Colorfastness to light is, “the degree to which a dye resists fading due to constant light exposure.” Although this may be particularly important when shopping for fabric that will be used in a sunroom or outdoors, it is important to note that all dyes have some susceptiblility to light damage. Problems with fading tend to occur when the fabric chosen was not produced to meet the end use, like using a basic multipurpose cotton print on patio furniture. Most fabric manufacturers complete UV tests that provide consumers with a rating that directly correlates with the fabric’s ability to resist fading or it’s lightfastness. The most commonly used method in the United States is the American Standard AATCC 169.3. With this test the fabric is exposed under specific conditions to a controlled light source which simulates the sun spectrum in Albuquerque, New Mexico.

1=Very Poor, High Degree of Fading and 5=Very Good, No Fading.

Manufacturers may also provide a lightfastness in number of sunlight hours. Any number of hours could be given, but outdoor fabrics usually rate anywhere from 500-2000+. The exact number of hours or years a fabric will last without fading is impossible to determine as there are many factors that come in to play, such as the type of dye used, fiber content of the fabric, sun intensity and geographical location.

Other factors that may affect lightfastness include temperature, humidity, and airflow. Keep in mind that we are affected by the sun’s UV rays all year round and even on overcast days. The sunlight that shines into our rooms in both summer and winter can cause color fading. Line draperies with protective lining and consider the harshness of the sun’s light through your windows when selecting a fabric. Remember, ALL fabrics will fade over time.

Check out the line of fabrics that we carry at www.greenhousefabrics.com