The Water Gun Knife: How You Cut 9 Million Pounds of French Fries a Day

McDonald's sells about 9 million pounds of fries a day. French fries don't come out of the ground that way. You've gotta cut them. How do you cut 9 million pounds of fries a day? With a water gun knife.

The process starts when the potatoes are brought in from the fields and offloaded onto a set of spinning rods. These rods separate the larger potatoes from the smaller ones, as well as dirt, rocks, and other debris. From there, the spuds are dumped into a system of water-filled chutes that clean and further sort them by size. The biggest and best taters are sent through a skinning machine that blasts them with steam for twelve seconds, boiling the water under their skins until the skin explodes off. Once skinned, the potatoes are ready for cutting.

The Water Gun Knife is basically a water cannon aimed at an array of blades. The potatoes are forced through a high-pressure line and launched towards the grid of sharpened steel at 117 feet per second. Whole potatoes go in, shoe string fries come out; just as when Gilbert Lamb first invented the device in 1960 (although his prototype used a fire hose).

[Lamb Weston - Rolling Stone Magazine via McSpotlight - McDonalds]

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