There are many publications dealing with the annealing of glass and with the single periods of the annealing curve. The conditions of the annealing resulting in practice are, however, not definitely determined, the quantity of breaking rejects due to inadequate annealing is relatively large, and its reduction is a task yet to be solved. The proper partition of the annealing curve, namely into the heating up, the holding or soaking, the real annealing, the after cooling, and the final cooling, has brought this problem nearer to solution. Many researchers studied the temperatures and times of each period and elaborated formulae. Some formulae for holding for the time during which the strains of glass disappear at a constant temperature, or diminish to practically admissible value, are known. However, if we use these formulae for calculations of he holding temperature and holding time considerable deviations result.
