Patent ID: 7493941

Claim:
A fin composed of a plate material having a non-degreased, non-surface roughened surface at least partially coated with a rolling oil and having a plate shape, comprising: a fin unit having the non-degreased, non-surface roughened surface at least partially coated with the rolling oil; and a coating film that is formed on the non-degreased, non-surface roughened surface of the fin unit that is at least partially coated with the rolling oil, the coating film including a corrosion resistant coating applied to the non-degreased, non-surface roughened surface of the fin unit that is at least partially coated with the rolling oil and a hydrophilic coating applied to the corrosion resistant coating; wherein in response to infrared spectrum measurement the coating film exhibits a peak in the infrared spectrum corresponding to the primary constituent of the rolling oil, and concave and convex portions on the surfaces of the coating film are in a range between 2 and 5 micrometers in the plate thickness direction.