That one I've never heard of, but there is a much better method for doing front sights at a match, and molds. It called: MASKING TAPE. It isn't toxic, and produces a fine soot making the front sight black with ZERO glare. The same can be used to smoke a sticking mold, but may or may not help depending on the cause.
On very fragile fingerprints at a crime scene, I have used it, and a feather brush to get the print to come up, whereupon, I photographed the print, and sometimes was able to lift it.
Pull about 10"of tape off the roll, double it, then twist it, then light it. It burns easily, smokes readily, no fumes, and is not too hot.