Have you ever tried cutting through a composition-shingle roof, only to find that your reciprocating sawblade has become totally fouled with tar and refuses to cut? It’s frustrating to stop every 6 in. or so to unclog the teeth. I solved this problem by switching to a plaster-cutting blade. Its symmetrical teeth are non-clogging, and they cut in either direction. Since they catch more often on the forward stroke, invest in the sturdiest bimetal blades. In my experience, Lenox blades (www.lenoxsaw.com) have proven to be the best — they don’t snap off, and can be straightened out if they bend.
William H. Brennen, Denver, CO