NDFR (Non Durably Fire Retardant) means fabric that has been treated with flame retardant chemicals. These chemicals, however, can be removed or their efficacy reduced by washing or wetting the fabric. NDFR fabrics can usually be dry cleaned but it is better not to wet them with water or steam.
DFR means that a fabric has been warranted by the manufacturer as being “durably” flame retardant. Unlike FR rated fabrics, those with DFR ratings offer flame retardancy for the life of the fabric, though they are not necessarily as flame retardant as IFR rated fabrics. There are conditions that can reduce the fabric’s flame retarding properties, as well, so regular testing is advised for theatres or other locations that make use of stage curtains with this rating.
IFR fabric is inherently flame retarding, which means that the fibres themselves resist the effects of fire, rather than being fire retardant due to a chemical application (in most situations). IFR fabrics are excellent solutions for situations where curtains will be in close proximity to light or heat sources that might pose a fire risk.
