Makes Old Soldering Iron Tips Like New! Sal Ammoniac, also called a tinning block, quickly cleans any carbon build-up that collects on the tip of a soldering iron. Simply rub the tip of a hot iron against the block and in seconds, the tip is clean, bright and hot. The 1/2 pound block lasts a long time. Measures approximately 4" x 2-1/2" x 1" high. For best results and longer lasting soldering iron tips, use the tinning block occasionally to re-tin the surface of your tip. A moist soldering iron sponge, such as item #5009, is ideal for routine maintenance while soldering to keep the tip clean.