Tales From the Floor: Optical Brighteners

The call comes in from a customer that says, “The carpet has a yellowish tint,” or “There are strange discolorations that weren’t there before.” Sometimes it follows a cleaning. Sometimes it shows up after some spots were removed. Either way, the carpet doesn’t look right.

The culprit

The culprit is often something most homeowners and sometimes professional cleaners have never heard of: optical brighteners.

Optical brighteners are chemical additives found in certain detergents, spot removers, and other maintenance products. Laundry detergents and fabric softeners are loaded with them. They’re the things that make “white’s whiter and brights brighter.” They are not approved for use on carpet because they prevent the carpet from performing as intended. When applied, they can negatively alter the color of the carpet, often leaving a yellowish appearance that cannot be removed.

Detection is done using an ultraviolet (UV) light. Carpet cleaned with a product containing optical brighteners will fluoresce vividly—glowing a blue-white color that stands out immediately against the unaffected areas.

The issue almost always traces back to a cleaning product that wasn’t approved for use on the carpet—sometimes applied by the homeowner, sometimes by a professional cleaner.

The lesson

The lesson: Always check the ingredients in the products you use. Test the cleaning agent before using it. How can you check whether a cleaning agent contains an optical brightener? Put a small amount on a white coffee filter (optical brighteners are not food-safe), rinse with water, then shine your UV light on it. If it glows, it has optical brighteners in it. Not every cleaning agent that claims to be safe for carpet actually is.