The convenience and appetite appeal of frozen foods developed a brisk postwar market for many vegetables and fruits, and it seemed a natural direction for product research in potatoes. Dunlap first experimented with potatoes cut into French fry strips, water-blanched and frozen. This saved the housewife the peeling and strip-cutting operation, but she still needed a deep-fat fryer in her kitchen and a cooking time of about 15 minutes for comparatively small quantities of French fried potatoes. Faced with an indifferent market reaction to the water-blanched product, Dunlap then tried deep-frying the potatoes before freezing. This proved to be the most significant development in the short history of potato processing and gave birth to a product which grew to a volume of billions of dollars each year.

After experimentation with laboratory size quantities of French fried potatoes, the research and development department at the Simplot Caldwell plant decided to make some experiments on production line techniques. For this, they purchased a second-hand fryer that had been employed in a potato-chip plant. Grouped around the fryer for the first production run were Vice-President Leon Jones, Food Technologist and Researcher Ray Kueneman, Chemist Ray Dunlap, and Production Maintenance Chief and Innovator Spencer Briant. The potatoes were passed through a peeler and through strip cutters and then water-blanched to prepare them for frying. The semi cooked potato strips were fed over a conveyor into one end of the French fryer, and the group waited eagerly at the other end to see the emergence of the golden strips of French fried potatoes. They had overlooked one fact, however. Thin-sliced potato chips float to the surface of frying fat; however, the French cut strips of potatoes sunk to the bottom of the fryer. As the group waited, not only did no French fries make their appearance at the discharge end of the fryer, but smoke began issuing from the surface of the boiling fat. The French fried potatoes were burning at the bottom of the fryer. More raw strips poured in but no finished French fries appeared as the burned strips accumulated.

Despite this temporary disappointment, the research and development team continued their efforts to produce French fried potatoes on a production line basis. The black-iron fryer proved to have another disastrous limitation. Cast iron in contact with hot frying fat produced a chemical reaction that caused the frying medium to break down rapidly and rancidity to develop. A fryer load of vegetable shortening had a very short life, and the odor that emitted from the fryer as the fat began to break down was almost impossible for employees to tolerate in the production line area.