LEAD-ACID STORAGE BATTERY ELECTRODE OF THE TUBE PLATE TYPE HAVING A NOVEL SHEATH OF A GLASS FIBER FABRIC WHEREIN THE YARNS ARE HELD AGAINST SLIPPAGE BY ISLANDS OF A THERMOPLASTIC MATERIAL. THE SHEATH IS MADE BY PASSING A TUBE MADE OF GLASS FIBER YARNS OVER A MANDREL WHICH EXTENDS THROUGH A CHAMBER CONTAINING PULVERIZED PARTICLES OF PLASTIC MATERIAL. THE PARTICLES ARE BLOWN ON THE GLASS FIBER TUBE WHILE HEATED AND FORM SMALL ISLANDS OF PLASTIC MATERIAL WHEN COOLED WHICH IMPART THE NECESSARY ME-

CHANICAL STRENGTH TO THE SHEATH WITHOUT SUBSTANTIAL REDUCTION IN POROSITY.