foot resulting in the plating application of approximately 36 g per foot of copper to the tube a boiling test comparison in freon r 11 of a one foot section of my improved plated tube and a similar length of unplated finned tubing heated internally with varying amounts of heat showed substantial improvement for the plated tube as evidenced by lower internal wall temperature readings for example when 150 watts of heating was supplied the unplated fin tube had an internal wall temperature as measured by a thermocouple of 44 u00b0 c while the plated fin tube had a temperature of 33 u00b0 c similarly for 100 watts of heating the respective temperatures were 38 u00b0 c and 30 u00b0 c for 50 watts of heating the respective temperatures were 32 u00b0 c and 27 u00b0 c and for 10 watts of heating the respective temperatures were 26 u00b0 c and 24 u00b0 c the plating may be carried out in an apparatus such as that indicated generally at 40 in fig3 the apparatus 40 comprises a vertical tank 41 filled with plating solution 42 and containing a tubular anode 44 of copper which is the source of the metal to be plated to the tube fins 12 the tube is prepared as shown in fig2 before it is plated so that the fins 12 are coated with an insulating coating 20 the coating can be applied in any suitable manner including rolling the tube on a porous surface coated with the coating material the tube preferably rests on an insulating block 48 of plastic or other suitable material the block 48 has internal passageways 50 and is seated to the tube by an o ring seal 52 a rubber stopper member containing an inlet air tube 56 is.