There is disclosed novel glass fiber particularly useful for preparing formed insulating articles having on the surface of the fibers an amorphous aluminum phosphate polymer wherein the polymer resiliently tacks the glass fibers together so as to provide regain of shape after deformation of the fibers as by compression. Also disclosed is a process for preparing glass fiber articles wherein the fibers are contacted with an ionic polymer which is then dehydrated to form an amorphous non-hygroscopic polymer.