Material: soda-lime glass. Glass beads made of highly pure soda-lime glass. Manufactured using a special process that enables the production of beads with extremely high roundness in sizes from 4 mm upwards. Use as agitating beads and mixing beads for aerosol sprays, as valve balls for bottle seals. Thanks to their high degree of purity, the glass balls are also suitable for use as grinding and dispersion balls for wet grinding of pigments, agrochemicals and biological or other preparations. Very smooth surface Low proportion of air bubbles Refractive index 1.5159 Specific weight approx. 2.5 g/cm 3 Chemical composition: SiO 2 68.1%; Na 2 O 15.0%; CaO 8.3%; MgO 2.5%; Al 2 O 3 3.3%; other 2.80%. Glass beads 20 mm, matt