ASTM D635

ASTM D635 Tests Burning Rate and Characteristics of Plastics

Understanding a material's flammability is necessary before it is used as a building material or made into product parts. The test for Rate of Burning and/or Extent and Time of Burning of Plastics in a Horizontal Position — also called the ASTM D635 test — was developed to assess the burning characteristics of a plastic material. VTEC Laboratories offers ASTM D635 as one of our many fire and flammability testing services for municipalities, the military and other industries.

What Is ASTM D635?

ASTM D635 testing determines the rate of burning for plastics. It's done on polymeric materials in a bar form used in parts of appliances and other devices. The test analyzes the response of the plastic material under heat and flame conditions, and the results indicate their flammability for certain applications. You can use the results to compare materials or assess production and quality controls.

The ASTM D635 test is required by the International Building Code (IBC) for plastics that transmit light and the Florida Building Code (FBC) High Velocity Hurricane Zone (HVHZ) to ensure the material meets the qualifications for an Approved Plastic.

ASTM D635 — Test Procedures and Results

The purpose of the ASTM D635 test is to create a reenactment of fire conditions to determine the material's flammability and hazards. Variables of the test, like specimen size and energy source, need to be constant to yield the best results.

During the test, the plastic material will be situated horizontally, so one end is supported and the other end is free. A gas flame will be exposed to the free end for 30 seconds. Then, the flame is removed so the extent of and time spent burning can be observed. The average burning rate is 100 millimeters from the burned end.

The results of the test — burning rate and time — indicates flammability, and they can be used to classify the material as CC2, HB or CC1, according to the appendix. The plastic material is considered acceptable depending on how it will be used in the equipment and if it meets the standards for that equipment. The burning rate will be affected by the plastic's density, thickness, anisotropy and pigments, so the ASTM D635 results should only be compared to similar materials.