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The inventors of a method to make all-plastic refrigerator doors are offering to sell their patents.

David G. Bank, president of Papago Plastics Inc. in Rochester, N.Y., and James Karlin, president of James Karlin Design of Fairport, N.Y., developed a method by which doors for refrigerators or freezers can be blow molded using a two-step process for the main structure, with shelves and other attachments added later.

The concept for the process derived from earlier industry attempts to blow mold a single-piece door — with little success, Bank said.

Karlin and Bank hoped their idea for doors would catch on with appliance makers. They demonstrated their concept at trade shows, and the process was featured in industry trade publications. But they attracted no partners.

``I am interested in the highest bidder,'' Bank said in a telephone interview. ``I know how much I have invested, and I am a reasonable man.''

Bank also hopes any buyer of the concept carries the project through to a completed product.

``Somebody is going to make this happen somewhere,'' Bank said. ``It's going to take somebody who's really going to champion this and challenge the industry to a whole new way of thinking.''

The benefits of an all-plastic door include a simpler manufacturing process, potential lighter weight and better insulation qualities, said Bank, who added he sees an all-plastic box as well as a door in the refrigerator's future.

On the negative side, appliance makers have a big investment in current metal-based manufacturing methods. And competition with other materials has driven the price of metal raw materials down, making the costs of retooling for plastics less attractive, according to Bank.

Consumers could also be disappointed with plastic doors because the ubiquitous refrigerator magnets would not stick to them, Bank said.

Another perceived problem with an all-plastic door is thermal bowing. When used on a refrigerator, the interior panel of the door is colder than the outside panel.

The temperature differential would cause the door to curve, potentially creating problems with its seal.

But Bank said the door could be made slightly bowed in the opposite direction during the molding process. When used in regular operating conditions, the thermal bowing of the door would actually make it seal flat against the box.

Bank's main business is rapid design and tooling of molds for injection and blow molders. He also acts as a plastic parts design consultant and has given seminars on the subject for a number of industry groups.

Karlin, who could not be reached for comment, is an industrial design specialist.

The pair hold U.S. patent numbers 5,306,082 and 5,454,997. European patents also are pending.