Temper number – the bottles shall after annealing, shoe no greater than real Temper Number 4 when examined under polarized light and compared to standard disks in accordance with American Society for testing and materials (ASTM) c 148-71, standard methods for polariscopic examination of glass containers. The relationship between real and apparent temper is shoen in appendix A. At least one bottle shall be taken from each side and center of the annealing lehr at least every 2 hours during manufacture and tested for temper number.