Try to use a circular motion while cleaning. Do not apply too much pressure on the tip in order to avoid damaging the coin or relics. Do not apply on a wet coin or object as it may damage the patina. The harder the tip is, the better it will get rid of hard deposits and dirt. The best tool to get rid of the crust is the scalpel; when you reach the surface of the object, use a softer/more accurate tool such as a hard tip or brush. If you have to clean a coin with a patina, use the fiberglass brush as it will not damage the patina.