Abstract: Low sodium hollow glass microspheres containing less than about 3 wt. % Na.sub.2 O are produced from aqueous precursors. The method comprisesa) forming an aqueous glass precursor solution or slurry by combining sources of cations contained in the glass, the solution or slurry comprising all of the glass cations in proportions substantially identical to those in the glass,b) forming the solution or slurry into droplets, andc) heating the droplets to form the microspheres.The precursor may also contain surfactants, blowing agents or other known expedients. Nonionic fluorocarbon surfactants are preferred.The droplets may be formed by spraying or any other known technique. The droplets may be spray dried prior to heating step c).

Abstract: Small hollow glass spheres are prepared by adding a surfactant to a liquid glass precursor mixture. The surfactant-containing solution or dispersion can be formed into droplets which are directed into a heated zone and the product collected in a cooler zone. Alternately, the solution or dispersion may be spray-dried, and the spray-dried product is fed into the heated zone and collected in the cooler zone. Nonionic fluorocarbon surfactants are the preferred surfactants.