The truth is that BHT is not used in the production of these materials. Third, some carpet manufacturers have tried to capitalize on the situation. One has offered to pay BHT yellowing claims - in the gulf coast area. Although these claims have indeed increased in recent years with the increasing market share of rebonded urethane cushions, the total number of complaints remains very small, but the issue has become highly visible. Carpet mills should continue to address yellowing claims on a case by case basis, and those found to be the result of causes other than BHT should be handled appropriately.
Some clarification is in order.
In considering yellow dis-coloration on site, the first step is to decide whether the yellowing represents a gain in color or a loss of color. Ozone preferentially destroys blue dyes first. With most carpet colors, this leaves the yellow and red components intact and the carpet turns a dull orange, not yellow. Further, this is a loss rather than a gain of color. Oxides of nitrogen yellowing - This rare phenomenon occurs in the manufacturing plant, when undyed nylon is stored for long periods in areas where air circulation is poor.