(a) Product process operations that finish leather for nonupholstery use are categorized as either water-resistant/specialty or nonwater-resistant product process operations. You must distinguish between the water-resistant/specialty and nonwater-resistant product process operations so that you can determine which HAP emission limit in Table 1 of this subpart applies to your affected source. Water-resistant and nonwater-resistant product process operations for nonupholstery use can be distinguished using the methods described in paragraph (b) of this section. Specialty leather product process operations for nonupholstery use can be distinguished using the criteria described in paragraph (c) of this section.

(b) To determine whether your product process operation produces water-resistant or nonwater-resistant leather, you must conduct the Maeser Flexes test method according to American Society for Testing and Materials (ASTM) Designation D2099-00 (incorporated by reference-see § 63.14) or a method approved by the Administrator.

(1) Statistical analysis of initial water penetration data performed to support ASTM Designation D2099-00 indicates that poor quantitative precision is associated with this testing method. Therefore, at a minimum, 36 leather substrate samples (i.e., three sections of leather substrate from at least 12 sides of leather), must be tested to determine the water-resistant characteristics of the leather. You must average the results of these tests to determine the final number of Maeser Flexes prior to initial water penetration.

(2) Results from leather samples indicating an average of 5,000 Maeser Flexes or more is considered a water-resistant product process operation, and results indicating less than 5,000 Maeser Flexes is considered a nonwater-resistant product process operation. However, leather samples resulting in less than 5,000 Maeser Flexes may be categorized as specialty leather in paragraph (c) of this section.

(3) For each leather product with a unique finish application, you must maintain records to support how the leather product was categorized to a product process operations type. You must repeat the leather product categorization to a product process operation type no less frequently than once every 5 years if the applied finish chemical characteristics of the leather product have not changed, or when the applied finish chemical characteristics of the leather product do change, whichever is sooner.

(c) To determine whether your product process operation produces specialty leather, you must meet the criteria in paragraphs (c)(1) and (2), or (c)(3) of this section:

(1) The leather must be a select grade of chrome tanned, bark retanned, or fat liquored leather.

(2) The leather must be retanned through the application of grease, waxes, and oil in quantities greater than 12 percent of the dry leather weight. Specialty leather is also finished with higher solvent-based finishes that provide rich color, luster, or an oily/tacky feel. Specialty leather products may include, but are not limited to, specialty shoe leather and top grade football leathers.

(3) The leather must be a high-quality dress or performance shoe leather that can withstand one of the visual tests in paragraph (c)(3)(i) or (ii) of this section:

(i) Moisture injection into the leather using vacuum mulling without signs of blistering.

(ii) Prolonged ironing at 200 °F for smoothing out surface roughness without finish lift off.

(4) For each leather product with a unique finish application, you must maintain records to support how the leather product was categorized to a product process operations type. You must repeat the leather product categorization to a product process operation type no less frequently than once every 5 years if the applied finish chemical characteristics of the leather product have not changed, or when the applied finish chemical characteristics of the leather product do change, whichever is sooner.

[67 FR 9162, Feb. 27, 2002, as amended at 70 FR 6360, Feb. 7, 2005]