Engines of Our Ingenuity

No. 2047:
FLEXIBLE SODA STRAW

by John H. Lienhard

Today, Invention in Microcosm. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

I've just found a short article by Martha Davidson that pretty well captures the process by which a new gadget first comes into existence, and then into use. It's about the flexible soda straw.

The story begins in 1936. Two-year-old Julia Friedman is at a soda fountain counter, trying to sip her drink through a straw that extends too far above the glass. She tries bending the straw, but now it kinks shut and won't let any liquid through. The short version of the story would be that her father, Joseph Friedman, went home and invented the flexible straw. Well, yes, but ...

Friedman had been inventing since he was fourteen. At 21, he'd received a patent for an ink gage to be used in fountain pens. He later sold it to the Sheaffer Pen Company. By the time he sat with his daughter in that drugstore, he held nine patents.

So now he ponders how to make a paper tube that'll bend without collapsing, and he recalls how we can bend a helical spring. So he places a screw inside a straw, then winds dental floss around the outside to create a helical indentation. Sure enough, he has a flexible elbow that won't collapse when the straw bends.

Later that year he files for a patent on his flexible straw, but now, instead of using dental floss, he proposes to roll an external die around an internal screw thread. He gets the patent, but can't find a buyer for it. What to do?

He decides to manufacture the straws himself. Then, of course, he faces the same problems that potential buyers had suspected in his design. But he's committed and these become problems that he has to solve. First, a helical winding doesn't make for a clean bend. Friedman soon realizes that he needs to make the indentations concentric rather than spiral.

Next he faces the problem that straws, once bent, will simply flop over. He solves that by coating the bend with a microcrystalline wax. Now they retain their position when they're bent.

By 1951, when Friedman has received a new patent with these improvements, his older sister Betty has created a marketing program with a Cleveland manufacturer. And that might be where the story ends. But I just stopped by my local pharmacy to buy a pack of 75 flexible straws for 99 cents. And what did I find?

Now the straws are plastic, not paper. Rolled indentations have been replaced with an accordion pleat. They're sold by pharmacies because the public finally informed flex straw makers of their most important use: It was not to be young children at soda fountains, but bedridden patients who have to drink at cup level.

I said at the beginning that we were about to see invention in microcosm, and indeed we have. Here's an invention so elementary that it looks like a straight jump from idea to store. In fact, it took decades of evolution and improvement involving everyone -- inventors, manufacturers, marketing, and finally us the users.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


M. Davidson, A flexible Mind. Invention & Technology, Vol 21, No. 3, Winter 2006, pp. 55-56.
Here you may find Davidson's article on line. And here is Davidson's article on soda straws in general.

Three views of a modern plastic accordion-pleated flexible soda straw:
   Top: The unbent "as is" straw
   Middle: The same straw bent about 130 degrees.
   Bottom: The unbent straw with the pleats pulled out.

Straight flexible straw
Bent flexible straw
Flexible straw pulled out

The Engines of Our Ingenuity is Copyright © 1988-2005 by John H. Lienhard.