40 CFR § 426.61
Specialized definitions
June 9, 2020
For the purpose of this subpart:
(a) Except as provided below, the general definitions, abbreviations and methods of analysis set forth in 40 CFR part 401 shall apply to this subpart.
(b) The term “tempering” shall mean the process whereby glass is heated near the melting point and then rapidly cooled to increase its mechanical and thermal endurance.