Technical Data Chemical Analysis
Composition
Si02: 70.8%, Na2O: 13.9%, CaO:8.2%, MgO: 4.4%, Al2O3: 1.9%, K2O: 0.4%, SO3: 0.3%, Fe2O3: 0.08%
Hydrolytic class
Standard DIN 12111: class 3 Standard ISO 718: class 3

Mechanical Properties
Density	2.5 g/cm3
0 to 100°C: 8.0 10-6 per °C or °K 0 to 200°C: 8.1 10-6 per °C or °K 0 to 300°C: 8.4 10-6 per °C or °K 0 to 400°C: 8.7 10-6 per °C or °K 0 to 500°C: 9.0 10-6 per °C or °K

Coefficient of elasticity for tension or Young's Modulus		E=70 109 Pa
Poisson's ratio	0.24
Hardness	Vickers Scale: 6.35 109 Pa	Mohs Scale: 6.5

Electrical Characteristics
Electrical bulk resistance	Dialectric constant
5 107: ohms.m for 1000Hz and 25°C	7.75 at 106 HZ and 25°C

Optical and Photometric Characteristics
Refractive index	Reflection
1.52 in visible range	=(n-1/n+1)2 with=0.04 for n=1.5 i.e. about 8% for the two faces.

Thermal Characteristics
Specific heat	Transformation point
1 103: J .kg-1	Tg:555 °C for viscosity of 1013.4 poises
Thermal conductivity at 20° C
1 kcal. m/h m2 °C=1 W.m-1. °K Normal emissivity factor 0.9

	Available Thickness
	mm		inch
	0.50 (0.381-0.635)		0.020 (0.015-0.025)
	1.02 (0.990-1.190)		0.040 (0.039-0.047)
	1.02 (0.950-1.050)		0.040 (0.037-0.041)
	1.52 (1.270-1.780)		0.060 (0.050-0.070)
	2.00 (1.900-2.150)		0.080 (0.075-0.085)
	2.30 (2.150-2.400)		0.090 (0.085-0.095)
	3.00 (3.000-3.300)		0.125 (0.118-0.130)
	4.70 (4.600-4.900)		0.188 (0.181-0.193)