A major concern in finding a fabric appropriate for theatrical use is fire retardancy. Many materials come flame retardant from the mill; others can be treated later. Still others, primarily synthetics and those containing metallics, cannot be flame proofed at all.
FR / Flame Retardant
FR Fabrics are woven with threads that are not initially considered fire retardant. The woven product is treated with a flame proofing compound through immersion to make it fire retardant. The flame proofing compound adheres to the outside of the fibers, but is water soluble. Painting, washing or dry-cleaning the material can remove the compound and void the fire retardancy. Even excessive humidity can have this effect over time. The fabric can be flame proofed again by spraying a flame proofing solution on to the backside of the fabric. A yearly field test to check the status is recommended.
IFR / Inherently Flame Resistant
IFR Fabrics are manufactured from polyester yarns to meet NFPA 701 testing protocol without any additional treatment. These fabrics are expected to retain their IFR properties for the life of the material, however, this cannot be guaranteed (more information). Conditions of use including time, humidity, excessive dust or dirt etc. may adversely affect the flame retardant capabilities. A yearly field test to verify the status is strongly recommended.
DFR / Durably Flame Resistant
DFR Fabrics are woven with threads that have some fire retardant qualities, but not necessarily enough to meet NFPA701 testing protocol. The material is treated with a chemical that chemically binds with the fiber composition rather than adhere to its surface. This chemical is not water soluble and is expected to withstand washing or dry-cleaning for an extensive period of time. As with IFR fabrics, however, conditions of use including time, humidity, excessive dust or dirt etc. may adversely affect the flame retardant capabilities. A yearly field test to verify the status is recommended.
NFR / Non-flame Resistant
NFR fabrics are woven with threads that are not fire retardant. They have not been treated, or cannot be treated.