Optical Brighteners

What are optical brighteners? How do they affect the performance of papers?

Optical brighteners are additives that are used in paper manufacturing to increase the perceived “whiteness” of the paper. Their use results in a whiter and brighter appearance, which can be desirable for many paper types.

However, for fine art papers there are advantages to selecting papers that do not contain optical brightener additives (OBAs). First, the natural white color, or what is known as “optically dead” papers, will remain consistent under different lighting conditions. In contrast, the color of papers that contain optical brighteners can shift depending on light source. Using “optically dead” papers is especially important for artwork that will be scanned for high quality reproductions. Another advantage is that the color of OBA-free paper will remain more consistent over time. While OBAs enhance the perceived whiteness and brightness of papers, they can break down over time, causing color shifts.

Strathmore® 500 Series Drawing, Bristol, Watercolor, Mixed Media and Marker papers as well as our 500 Series Illustration and Mixed Media boards are considered optically dead. In addition, our 300 and 400 Series Sketch, Drawing, Bristol, Watercolor and Mixed Media papers are manufactured without adding any optical brighteners during the production process. Although no OBAs are added in the papermaking process of our 300 and 400 Series papers, trace amounts of optical brighteners can sometimes be present in the pulp used to create the papers.