2.
Council Directive 69/493/EEC of 15 December 1969 on the approximation of the laws of the Member States relating to crystal glass · European Union
PHYSICAL DETERMINATIONS 2.1. Density Method by hydrostatic balance to within ± 0.01. A sample of at least 20 grammes is weighed in air and weighed immersed in distilled water at 20 ºC. 2.2. Refractive index The index is measured on the refractometer to within ± 0.001. 2.3. Microhardness Vickers hardness is to be measured according to the standard ASTM E 92-65 (Revision 1965) but using a load of 50 grammes and taking the average of 15 determinations.
Source: EUR-Lex (Cellar) · retrieved 2026-11-02 · Text as adopted (Official Journal); later amendments are not incorporated in this text.