Abstract: Apparatus is provided for making a permanent mark on a hard surface such as glass or the like primarily for identification purposes. A hand held gun connected to a source of compressed air is adapted to drive a stream of abrasive particles towards a stenciling head on the marking end of the gun, which is held against the surface to be marked. The head carries interchangeable stencils located in the path of the stream of abrasive particles when the gun is actuated. When the stencil head of the gun is held flat against the surface which is to be marked and the gun actuated, the stencil indicia will be formed on the surface by the action of the abrasive particles abrading and etching the surface through the stencil openings. The stencil elements are formed by photo engraving techniques to produce sharp, precise characters and the elements themselves fit snugly together when assembled to prevent leakage between adjacent elements.

Abstract: Damaged screw propellers are repaired by use of hollow, thin-walled envelopes, each envelope having surfaces corresponding in configuration to an outer portion of a screw propeller blade. Each envelope is located on a blade, and a workable material is interposed between the damaged blade portion and the hollow interior of the envelope. The workable material and the envelope become an integral part of the blade to substantially duplicate the original configuration of the blade.

Abstract: An easily ignitable charcoal briquet system is provided for use especially in making small, outdoor cooking fires. The system includes wax-impregnated charcoal briquets in combination with starting pads of wax-impregnated paper or the like. The briquets are impregnated with a hot wax in a two-stage operation to produce a charcoal having two strata of wax impregnated below the surface of the briquets, which enhances ignition and burning characteristics of the briquets. The starting pads preferably are of non-woven paper material having uncoated corners, a light coating of wax along the outer margins thereof, a heavy coating of wax about an inner border thereof and an uncoated central portion. Wax impregnated briquets are piled in the uncoated center portion of the pad, which is ignited by lighting the uncoated corners thereof. The edges of the pad may be corrugated to facilitate ventilation.