Abstract: A method of, and apparatus for, repairing mechanical and/or chemical damage to the surface of glass bottles destined for re-use. A bottle to be repaired is brought to a temperature in the region of the transformation point of the glass of the bottle, its surface is thermally treated with laser beams, and during the treatment the bottle surface is linearly scanned with the laser beams while rotating the bottle about its longitudinal axis to repair the surface. The apparatus comprises a laser source and optical means for directing the laser beam generated by the laser source onto the surface of a bottle being treated.

Abstract: Method for the production of mineral fibers resistant to alkaline media which are to be used for the micro-reinforcement of cement-, lime- and/or plaster-bound or bituminous binders or building materials. The starting material is a mixture of extrusive rocks with an addition of 4 to 6 weight percent of ZrO.sub.2, based on the end product, in a composition that is readily fusible and easy to process into fibers of high mechanical strength and resistance to alkaline media. The mixture is fused at a temperature between 1350.degree. and 1500.degree. C. and is then processed into fibers 10 to 20 .mu.m in diameter.