FR means that the fabric has passed applicable NFPA testing
procedures. Technically, this means any fabric that meets the standard. Informally, we refer to FR fabrics as natural fiber fabrics, such as cotton, that have been treated with a chemical that allows them to pass the applicable NFPA test
.In time, these chemicals will break down and no longer be effective. If the fabric gets wet, the chemical may leach out. You might see this as a white chalky line on the curtain, which would indicate testing
should be performed.Retreating curtains in the theatre is difficult. It’s messy, and if enough of the chemical is sprayed on the curtain to be effective, the fabric gets so wet it is almost impossible to get rid of the chalky lines. Curtains also tend to look dirty and oily after retreating. Professional cleaning and retreating through BellaTEX is available, but the cost can be almost equal to replacement for many curtains. Very ornate or complex curtains that are expensive to produce can be an exception to this rule.
In most instances, by the time the curtain needs retreating it will have become structurally unsound. In humid parts of the country re-treatment can be necessary in as soon as 5 to 7 years; in dryer areas it may be 10 years or more before re-treatment is necessary.
Note that we use the terms fire/flame “resistant” or fire/flame “retardant” and not fire/flame “proof”. Under enough heat and pressure anything will burn! While FR stage curtains are resistant to combustion they are not intended to be a protective device. The intent is for them to not become additional fuel in the event of a fire.