Abstract: An improved trowel for facilitating the production of air pockets in a layer of mortar mix applied to a substrate for receiving marble-flooring pieces thereon. The trowel comprises a handle and an elongated blade joined together by a shank. The shape of the blade gradually narrows to a distal end that includes a plurality of tips separated by one or more V-shaped notch or notches. In various versions of the invention, the number of tips may vary and the tips may be flat or pointed. The V-shaped notch or notches may vary in depth.