Section 1610.4 - Requirements for classifying textiles(a)Class 1, Normal Flammability. Class 1 textiles exhibit normal flammability and are acceptable for use in clothing. This class shall include textiles which meet the minimum requirements set forth in paragraph (a)(1) or paragraph (a)(2) of this section.(1)Plain surface textile fabric. Such textiles in their original state and/or after being refurbished as described in § 1610.6(a) and § 1610.6(b) , when tested as described in § 1610.6 shall be classified as Class 1, Normal flammability, when the burn time is 3.5 seconds or more.(2)Raised surface textile fabric. Such textiles in their original state and/or after being refurbished as described in § 1610.6(a) and (b) , when tested as described in § 1610.6 , shall be classified as Class 1, Normal Flammability, when the burn time is more than 7.0 seconds, or when they burn with a rapid surface flash (0.0 to 7.0 seconds), provided the intensity of the flame is so low as not to ignite or fuse the base fabric.(b)Class 2, Intermediate flammability. Class 2 fabrics, applicable only to raised-fiber surface textiles, are considered to be of intermediate flammability, but may be used for clothing. This class shall include textiles which meet the minimum requirements set forth in paragraph (b)(2) of this section. (1)Plain surface textile fabric. Class 2 is not applicable to plain surface textile fabrics.(2)Raised surface textile fabric. Such textiles in their original state and/or after being refurbished as described in § 1610.6(a) and (b) , when tested as described in § 1610.6 , shall be classified as Class 2, Intermediate Flammability, when the burn time is from 4.0 through 7.0 seconds, both inclusive, and the base fabric starts burning at places other than the point of impingement as a result of the surface flash (test result code SFBB).(c)Class 3, Rapid and intense burning. Class 3 textiles exhibit rapid and intense burning, are dangerously flammable and shall not be used for clothing. This class shall include textiles which have burning characteristics as described in paragraphs (c)(1) and (c)(2) of this section. Such textiles are considered dangerously flammable because of their rapid and intense burning. (1)Plain surface textile fabric. Such textiles in their original state and/or after refurbishing as described in § 1610.6(a) and § 1610.6(b) , when tested as described in § 1610.6 , shall be classified as Class 3 Rapid and Intense Burning when the time of flame spread is less than 3.5 seconds.(2)Raised surface textile fabric. Such textiles in their original state and/or after refurbishing as described in § 1610.6(a) and § 1610.6(b) , when tested as described in § 1610.6 , shall be classified as Class 3, Rapid and Intense Burning, when the time of flame spread is less than 4.0 seconds, and the base fabric starts burning at places other than the point of impingement as a result of the surface flash (test result code SFBB). Table 1 to § 1610.4 -Summary of Test Criteria for Specimen Classification
[See § 1610.7 ]
| Class | Plain surface textile fabric | Raised surface textile fabric |
| 1 | Burn time is 3.5 seconds or more. ACCEPTABLE (3.5 seconds is a pass) | (1) Burn time is greater than 7.0 seconds; or (2) Burn time is less than or equal to 7.0 seconds with no SFBB test result code. Exhibits rapid surface flash only. ACCEPTABLE-Normal Flammability. |
| 2 | Class 2 is not applicable to plain surface textile fabrics | Burn time is 4.0 to 7.0 seconds (inclusive) with base burn (SFBB). ACCEPTABLE-Intermediate Flammability. |
| 3 | Burn time is less than 3.5 seconds. NOT ACCEPTABLE | Burn time is less than 4.0 seconds with base burn (SFBB). NOT ACCEPTABLE-Rapid and Intense Burning. |
Note: SFBB poi and SFBB poi* are not considered a base burn for determining Class 2 and 3 fabrics.