Abstract: In welding metal sheets together from only one side, an improved welding backup tape is self-adhesively applied to insure the consistent formation of a smooth, inclusion free, slightly convex underbead which requires little or no dressing, or grinding, and which does not impede in any way the achievement of 100% radiographic weldment testing. This welding backup tape is made in one embodiment by mixing into solution two parts of a colloidal silica solution with one part of a titanium dioxide refractory coating solution. Applying this resulting solution as a refractory coating to the upper portion of an electrical grade, heat treated, braided, natural finish, finely woven, fiberglass material in a sleeving configuration.