Legal Textiles
A longer burn time is the safer result. The test measures how slowly flame travels, not how much it burns.
— mm/s
Rate over the marked length in the test geometry
The 45-degree method is a **screening test for flame spread rate under one highly specific geometry** — a flat, taut, conditioned specimen at a fixed angle with a one-second ignition. It is not a fire hazard assessment and does not describe how a worn garment behaves: drape, fit, air gap, seams, multiple layers, contamination and the wearer's movement all change the outcome, generally for the worse. Extrapolating the rate across a garment dimension assumes uniform spread that a real garment does not provide. The heat release figure assumes complete combustion of the swept material and is an order-of-magnitude indication only. **Legal and liability conclusions require testing to the applicable standard by an accredited laboratory and interpretation by a qualified fire investigator.**
45-Degree Flammability Burn Rate & Flame Spread Reconstructor — free, with the formula and a worked example, at Textile School.