Understanding Optical Brighteners
A chemical from the past that is still encountered from time to time in leaning or corrective products, and of which a cleaning technician must be aware of due to problems it may create, is optical brighteners. Prevalent in janitorial type cleaners when I entered the cleaning field in 1970, brighteners have developed a reputation as “bad actors” over the years—a reputation they may very well deserve. Properly used and applied, optical brighteners may solve some problems and improve results of cleaning or corrective attempts. Conversely, if they are improperly used or applied, then they may create problems that cannot be corrected and lead to carpet replacement. So what are these compounds and what problems can they create?
Optical brighteners are actually ultraviolet dyes that may be invisible under many lighting conditions. They work by fluorescing the ultraviolet light into visible light, thereby making surfaces they have been applied to appear brighter. This results in a cleaner, brighter appearance in these areas. Used properly on carpets and upholstery and other fabrics, this may result in a “cleaner clean.”
As a young lad, my mother used a blueing agent in the wash to make white sheets and clothing appear to be whiter and brighter. However, for an optical brightener to work properly, it must be exposed to ultraviolet light usually from sunlight; thus, they’re not of much value if the light falling on the treated surface is mainly incandescent (light bulbs).
Applied to areas without ultraviolet or sunlight exposure, optical brighteners add nothing to the appearance and will be invisible. So, it doesn’t seem to create any problems for the cleaner or the client. But there are potential pitfalls to their use, especially if they are unevenly applied.
Commonly, a carpet cleaner may encounter what appears to be bleach spots on carpet or upholstery where there has been an uneven application (such as a spotter) and a client demands the bleached spot be corrected. Unfortunately, correction is impossible since these materials are actually dyes. A temporary correction is to move the “bleached” surface to an area that doesn’t receive ultraviolet light, such as a shady area outside or a room without windows. This may work with a piece of upholstery, but may be impossible with a carpet. Even though there is no bleaching of the fabric and no dyes have been removed, the cleaner may end up replacing the product which suffered the “bleaching.”
By now, you’re probably wondering where these “bad boys” may be in your cleaning product pantry. They’ve been used for many years in browning correction treatments and in many spotting agents, especially those formulated for consumer use. I’ve seen carpets badly discolored by an uneven application of browning correctors in areas that are exposed to bright sunlight.
One case I see regularly is the living room of a client I clean for three to four times per year. I’ve asked her repeatedly not to use prepared spotting agents to clean up the mess caused by hairballs coughed up by her cat, and I have even recommended a spotter mixed from a laundry detergent. She continues to “forget” what I have told her. When the bright morning sun falls on her cream-colored carpet, it appears to have numerous bleached out white spots. Come back later in the day when the sun is on the other side of house or after sunset, and the spots are gone.
Since she was blaming me for the problem, I took out the long wave UV light (black light) I use to locate urine spots and directed it onto her spots. Lo and behold, they glowed a brilliant blue/white color characteristic of optical brighteners. At least we put the issue of blame to rest. They are indeed her spots, not mine. Keep that trick in mind if the situation arises.
But there are more possible problems with optical brighteners. Often, they are cationic in nature and are therefore not compatible with stain resistant nylon carpets, such as StainmasterÒ. The treatments applied to stain resistant carpets are anionic in nature. The protection they offer will be neutralized by cationic agents, thus the stain resistance will be lost in the areas they are applied. While the loss of stain resistance cannot be detected by the casual viewer, it may become evident if a normally removable spot-causing material, such as red soft drinks, turns into a permanent stain.
There are additional potential problems with the use of optical brighteners. One of these is its tendency to yellow with age, which is one the reasons that carpet and furniture manufacturers discourage its use. If yellow spots, “bleached spots,” and loss of stain protection don’t concern you, then go ahead and use them. But don’t say I didn’t warn you!
Fortunately, many chemical formulators particularly those that cater to the carpet and fabric cleaning industry, have stopped using optical brighteners. However, optical brighteners are still used quite often by formulators that supply the janitorial industry.
A couple of things have become clear over the past decade or so: brightener manufacturers say there is no place in the carpet/upholstery cleaning industry for brighteners. Most carpet and upholstery manufacturers agree wholeheartedly with this opinion, as do I. To determine if the cleaning agents you use contain optical brighteners, ask your salesperson or read the label closely. You can also expose the product to a black light. Conduct your own experiment and test a few spot removal products yourself.
By the way, the client who cleans up the hairballs with a spotter that contains optical brighteners recently had her 13-year-old nephew visit her and he brought along his black light. She said it was quite a sight when he turned on his black light in the living room the evening. All the cat spots became quite apparent! Until next month, seeya!