cannot be removed intact in the way described above unless the wire leads are long and flexible enough to be pulled out one by one. For a component such as a Dual-Inline Package (DIP), the pins are too short to pull out, and solder melted on one joint will solidify before another can be melted. A technique sometimes used is the use of a large soldering-iron tip designed to melt the solder on all pins at once; different tips are required for different packages. The component is removed while the solder is molten, most easily by a spring-loaded puller attached to it before heating. Otherwise all joints must be freed from solder before the component can be removed. Each joint must be heated and the solder removed from it while molten using a vacuum pump, manual desoldering pump, or desoldering braid. For through-hole mounted devices on double-sided or multi-layer boards, special care must be taken not to remove the via connecting the layers, as this will ruin the entire board. Hard pulling on a lead which is not entirely free of solder (or with solder not thoroughly molten in the case of a soldering iron tip heating all pins) may pull out a via. To remove and recover all components, both through-hole and surface-mount, from a board which itself is usually no longer needed, a flame or hot air gun can be used to rapidly heat all parts so they can be pulled off. Parts may be damaged, and toxic fumes emitted, if excessive temperature or prolonged heating is used. Surface mount If they do not need to be re-used, some surface-mount components can be removed by cutting their leads and desoldering the remnants with a soldering iron. Otherwise, surface-mount components must be removed by heating the entire component to a temperature sufficient to melt the solder used, but not high or prolonged enough to damage the component. For most purposes, a temperature not exceeding for a time not exceeding 10 seconds is acceptable. The entire board may be preheated to a temperature that all components can withstand indefinitely. Then localised heat is applied to the component to remove, with less heating required than from cold. Most frequently, a hot air (or hot gas) gun, with a nozzle of appropriate size and shape, is used to heat the component, with nearby components shielded from the heat if necessary, followed by