Finned tube evaporators are bare tube evaporators upon which fins have been installed to transfer heat from the air to the vaporizing refrigerant contained within. The fins act as a secondary heat absorbing surface, improving evaporator efficiency by increasing overall evaporator surface area while reducing coil size, weight, and cost. Finned evaporators are used quite extensively in residential and commercial refrigeration and air conditioning applications. In order for them to be effective, there must be good thermal contact between the evaporator fins and the tubing surface. This can be accomplished by several ways; one method is to solder the fin directly to the tubing. Another method is to slip the fin over the tubing and expand the tubing so that the fin locks onto the tubing surface. Once in place, the flare can be straightened out, securing the fin to the tubing.