7500 r p m to produce a strand travel of approximately 12 000 to 15 000 feet per minute other methods of applying the size to the strand of glass fibers such as pad applicator may be employed and the strand may be formed by means other than winding on the forming tube such as by means of a pair of rotating wheel pullers which direct the strand into a suitable collecting device the glass fiber strands wound on the forming tube are then dried this may be done by heating them at a temperature and for a length of time sufficient to reduce the moisture level to that appropriate for further processing for example at about room temperature for 48 hours for twisting or 8 to 12 hours at 270 u00b0 f for producing roving this drying causes the coupling agents to fix themselves to the glass surface and to produce the degree of strand integrity and moisture level required for processing the strand into roving yarn cord woven cloth or woven roving the solids content of size on the strands averages about 0 2 to 2 0 per cent by weight preferably about 0 50 per cent by weight the g 75 strand is twisted to form 0 5z yarn and is coated with the rubber adhesive described in conjunction with the testing of the samples.