Method for coating surfaces

Claim 1

An improved method for forming a film on a surface comprising establishing a first zone of vapors of a volatile organic solvent employed in coating composition containing the film forming agent, said zone being at atmospheric pressure and at the atmospheric boiling point of said organic solvent. establishing a second zone of vapors of said volatile organic solvent in interfacial relationship with said first zone but substantially free of direct contact with the ambient atmosphere, said second zone being maintained at a temperature above the atmospheric boiling point of said organic solvent by supplying heat to said zone external of said heat of vapors arising from the coating composition or the first zone; introducing the surface to be coated into said first zone; applying the coating composition to said surface upon the surface reaching equilibrium with said zone; introducing said coated surface into said second zone and maintaining said coated surface and said second zone in such condition that solvent will evaporate from the applied film at a controlled rate such that the film is gelled to prevent its sagging, held in this gelled state in said second zone for a time sufficient for surface imperfections to level out, and finally dried to a tack free and essentially solvent free condition, the surface being then at a temperature above the atmospheric boiling point of said organic solvent; and removing said surface from said second zone through said first zone or a third zone of the same nature as said first zone into the ambient atmosphere.