Tim Nelson

You are about to clean a sofa but notice upon inspection the white cotton fabric is showing faint yellowing on the seat and back cushions. The yellowing is not uniform; rather, it is blotchy in appearance. You look for similar problems on other areas of the sofa but cannot find evidence anywhere else on the base or frame. You show your client, supervisor, or cleaning staff what you’ve found, but they have no idea what may have caused the problem. The sofa is a little over a year old, has never been cleaned, and is only used occasionally. What is causing this discoloration? Is there any reason to do more than just clean it as usual? A History on Upholstery Upholstered furniture — such as furniture you might find in a waiting room, hotel, or lobby — can be both a starting point for fires and a substantial source of fuel for fires that originate elsewhere in a facility. However, after several decades of study, California is the only state with a flammability standard for residential, upholstered furniture like this. With no federal standard, California passed its own law in 1975. Technical Bulletin 117 (TB 117) specified mandatory test procedures for all residential, upholstered furniture. In the absence of a federal standard, and with California representing a substantial portion of their overall business, many furniture manufacturers chose to implement TB 117 for their entire lines. These decisions assured that furniture manufactured to the new standard would eventually be shipped throughout the United States. Flame-Retardant Chemistry In addition to other requirements, TB 117 specified that any feather-type filling material had to be encased in a flame-retardant ticking. Ticking is the fabric “bag” that holds the filling material. Since “down-proof” cotton ticking was already widely used in the furniture industry, the new standard was met by simply applying flame-retardant chemicals to these fabrics. (To simplify, we will use the term “down” to mean any filling material made from down, feathers, or combination of the two.) Cotton, a cellulosic fiber, can easily ignite in any fire situation. It is also among the easiest to treat for flame resistance. In fact, the least expensive types of flame-retardant chemistries — often based on inorganic salts — tend to perform well when applied in moderate amounts on cellulosic fabrics, such as cotton. These inexpensive chemicals are nondurable (they are water soluble), but in certain, less-demanding applications, such as the ticking specified by TB 117; they are a very attractive solution. Flame-retardant chemicals based on inorganic salts may be benign when first applied; however, these chemicals have at least one significant drawback: They decompose over time, forming acids. Even moderately strong acids can do serious damage to certain textiles, especially with prolonged exposure. Cover Fabric Sensitivity When a down-filled ticking is placed inside a cover fabric to form a seat cushion, the ticking and fabric are in intimate contact. This is important, because any chemicals (such as flame retardants) applied to the ticking are now more likely to transfer to the cover fabric. In the case of flame-retardant chemicals, the transfer is almost inevitable. The variable is the amount of flame retardant that moves and the time it takes to occur. Another variable, and part of what makes this problem so interesting, is the different sensitivities of upholstery fabrics. Cotton is resistant to damage from alkaline chemicals but is susceptible to damage by acids. Acids cause hydrolysis of the cellulose polymer, resulting in a weakening of the fiber. This damage is often accompanied by yellowing or browning, especially on white or light-colored fabrics. It is not unusual to find discoloration in the cotton ticking fabric in advanced stages of flame-retardant-induced damage. The flame-retardant-induced browning of cotton may look like the “cellulosic browning” that sometimes appears shortly after cleaning cotton (and other cellulosic) fabrics. However, browning due to flame retardant is caused by actual fiber damage. It is not correctible or preventable with application of acidic chemicals, such as those commonly used as rinse agents. If anything, acid rinses are likely to accelerate fiber damage caused by acidic, flame-retardant. Interestingly — and for reasons we don’t completely understand — we have not seen damage that we can definitively link to flame retardants on other cellulosic upholstery fabrics, such as linen. Additionally, synthetic fibers are resistant to acids, and this is why we have not seen damage on fabrics of this type. Fiber Reactive Dyes Certain types of fabric dyes also seem to be particularly sensitive to the effects of acid byproducts in flame-retardant chemicals. What little literature there is on the subject suggests that these are primarily reactive dyes, though no detailed studies have been found. Color changes caused by acid byproducts can be remarkable — imagine blue/gray becoming orange, blue changing to pink, and green turning to brown. The typical scenario can occur anywhere from a few weeks to a couple of years after the furniture has been installed. In all cases, the problem develops gradually and grows steadily more pronounced with time. Recognizing the Problem While flame retardant treatments are the norm for ticking fabrics encasing down fill, our experience suggests these chemicals are rarely applied directly to upholstery fabrics intended for residential installation. Among the estimated 150 to 200 instances of flame-retardant problems with which we have been involved since the early 1990s, we have seen only one or two where the discoloration was present in areas other than cushions. Furnishings exhibiting flame-retardant ticking problems tend to share several common characteristics: Material: Cover fabrics are almost always made from cotton (or a cotton blend). Affected areas: Again, because flame-retardant ticking is used almost exclusively within seat and back cushions, the problem is almost always limited to these items. Blotchiness: The discoloration will be uneven in appearance. As previously mentioned, color changes tend to be two different types: 1) dye-related changes, such as blue dye changing to pink, or 2) the yellowing/browning of light-colored fabrics. Absence of discoloration in narrow areas directly adjacent to seams: The

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Tim Nelson

Fiber-Seal Systems, Director of Research

Articles by Tim Nelson

Upholstery Fabric Damage: Let’s Get Technical

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