Flame Resistant Guide – Vertical Flame Test Results

Carhartt FR Fabric Testing

 Vertical Flame Test Results on Home and Industrial Laundered Fabric Samples Illustrates Durability of Carhartt’s FR fabrics

ASTM F1506: ASTM F 1506 is the Standard Performance Specification for Flame Resistant Textile Materials for Wearing Apparel for Use by Electrical Workers Exposed to Momentary Electric Arc and Related Thermal Hazards.  Fabric manufacturers use ASTM F1506 to evaluate the flame resistant properties of fabrics in response to heat and flame under controlled laboratory conditions. 

The Test: The standard requires fabric samples to be subjected to the ASTM D6413 Vertical Flame Test. In this test, FR fabric samples are exposed to a 12 second burn test. Once the flame has been removed, the fabric must self-extinguish within 2 seconds and the fabric’s char-length must be less than 6 inches (To pass Carhartt quality standards the fabric char-length must be less than 5 inches). 

Most fabric manufacturers use the Vertical Flame Test to evaluate the flame-resistant properties of FR fabric after being subjected to 100 industrial launderings.  However, Carhartt guarantees flame-resistant properties for the useful life of its FR garments regardless of the number of washings, provided laundering instructions are followed.  Therefore, to show the durability and consistency of the FR treatment, Carhartt required the vertical flame test be performed on swatches that had been through 200 Industrial launderings.

The Test Results: The chart below shows the char-length measurements for unwashed swatches, swatches home laundered up to 200 times, and swatches industrial laundered up to 200 times  As the chart illustrates, Carhartt garments still maintained their FR properties after 200 industrial launderings (equivalent to approximately 400 home launderings) demonstrating the permanent nature of the molecular bond formed during the FR treatment process.

Vertical Flame Test Results on Home and Industrial Laundered Samples

(Char Length Measured in Inches)

HL – Home Launderings   IL – Industrial Launderings