Method of fabricating air filters

A method of fabricating a high-efficiency air filter unit comprising:

• (a) forming a filter core by folding a continuous sheet of filter media at evenly spaced intervals in accordian fashion, thereby providing a plurality of side-by-side pleats;
• (b) forming first and second shallow, pan-like structure from planar sheets of substantially the same rectangular dimensions as the ends of said core formed by the zig-zag pleat edges with four relatively narrow strips, one attached to and extending upwardly from each of the four side edges of said sheets;
• (c) filling said first pan-like structure to a predetermined depth with a first quantity of liquid adhesive hardenable to a solid state;
• (d) submersing one of said core ends in said first quantity of adhesive within said first pan-like structure to an extent at least sufficient to immerse all of the zig-zag pleat edges of said one end in said liquid adhesive;
• (e) allowing said first quantity of adhesive to harden;
• (f) filling said second pan-like structure to said predetermined depth with a second quantity of said liquid adhesive;
• (g) inverting said core with said first pan-like structure adhered thereto and submersing the opposite of said core ends in said second quantity of adhesive within said second pan-like structure to an extent at least sufficient to immerse all of the zig-zag pleat edges of said opposite end in said liquid adhesive;
• (h) allow said second quantity of adhesive to harden;
• and
• (i) assembling a pair of rectangular end plates of substantially the same dimensions as the pleat walls of said filter core in sealing engagement with the endmost pleats of said core and with said planar sheets along adjacent edges of said plates and sheets, thereby forming a four-sided structure enclosing said core in sealing engagement on four sides.