A full-mount violin bow means that the base of the frog from the point of string entry to the bow stick, has been lined in a metal alloy. The frog is the box at the base of the bow. The alloy begins with the round nut that is used to tighten and loosen the strings and stretches around the entire base and across the side section of the frog. While the preference is largely personal and aesthetic, many advanced bows use a full-mounting process as it provides extra support, strength and better resilience to withstand the tension of the strings.
Half-mounted bows are more commonly found in student model violin bows. With a half-mounted bow, the metal alloy at the base of the frog only extends halfway across the bottom of the frog and does not extend to the side. This half mounting procedure generally costs less money. Since the mount does not wrap around the side of the frog, it is more prone to stress and breakage from the tension of the bow.
Bow mounts consist of nickel, silver, gold or mother of pearl. The more expensive bows will use silver, gold, or mother of pearl, which provides a better quality metal that is less prone to rusting. Nickel is most commonly used on student violin bows. This is one quick way to instantly determine the quality of a bow. The materials used don't affect the sound of the instrument, but they do have an effect on the appearance and feel of the bow.
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The mount helps to reinforce the frog. If the frog was made entirely of wood, it would break and crack from the tension of the strings. A half-mount bow is less secure than a full-mount. The full-mounted bows will protect the entire length of the frog. Half-mounted bows generally must be lighter since the mount must be weight-balanced with the rest of the bow. Purchase a full-mounted bow if you are a professional and need a high-quality bow. For students, a half-mounted bow makes more sense, since as you develop your skill you will naturally change your preferences and playing style.