Engineering the Disposable Diaper

Adventures in product design.

For the mothers of the baby boom, pediatrician Benjamin Spock’s child care handbook was a practical, confidence-boosting essential. Originally published in 1946 as The Common Sense Book of Baby and Child Care, Dr Spock’s baby book sold more than 500,000 copies in its first six months. By the time the second edition came out in 1957, with the simplified title Baby and Child Care, Dr Spock was selling a million copies a year. My mother, who was 24 when I arrived in 1960, still remembers the book’s reassuring tone.

‘You know more than you think you do’, the author told readers. ‘We know for a fact’, he wrote with medical authority, ‘that the natural loving care that kindly parents give to their children is a hundred times more valuable than their knowing how to pin a diaper on just right’.

Dr Spock went on to provide detailed instructions on the practical intricacies of parenthood, including diapers. Buy at least two dozen, he counseled, more if you aren’t washing them daily. Six dozen would cover all contingencies. With a diagram, he showed how to fold a diaper and explained how to position it on a boy versus a girl. ‘When you put in the pin’, he advised, ‘slip two fingers of the other hand between the baby and the diaper to prevent sticking him’. The book covered when to change the diapers and what to do with the dirties.

You want a covered pail partially filled with water to put used diapers in as soon as removed. If it contains soap or detergent, this helps in removing stains. Be sure the soap is well dissolved, to prevent lumps of soap from remaining in the diapers later. When you remove a soiled diaper, scrape the movement off into the toilet with a knife, or rinse it by holding it in the toilet while you flush it (hold tight).

You wash the diapers with mild soap or mild detergent in [the] washing machine or washtub (dissolve the soap well first), and rinse 2 or 3 or 4 times. The number of rinsings depends on how soon the water gets clear and on how delicate the baby’s skin is. If your baby’s skin isn’t sensitive, 2 rinsings may be enough.

On this subject, the 1957 edition contains two telling differences from the original. In 1946, Dr Spock recommended the knife method to those without flush toilets. And starting with the second edition, he advised new parents to buy an automatic washer and dryer if they could possibly afford them. ‘They save hours of work each week, and precious energy’, he wrote. ‘Energy’ in this case referred not to electricity or gas but to maternal stamina.

Disposable diapers did exist, but they accounted for a mere one percent of US diaper changes. They were expensive, specialty products and not that great. ‘The full-sized ones are rather bulky’, noted Dr Spock. ‘The small ones that fit into a waterproof cover do not absorb as much urine as a cloth diaper and do not retain a bowel movement as well’. Disposables were mostly used for travel, when washing diapers wasn’t an option.

But even as the second edition of Baby and Child Care was hitting bookstores and supermarket racks, change was afoot. After buying Charmin Paper Company in 1957, Procter & Gamble began looking for ideas for new paper products.

Motivated by the less pleasant aspects of spending time with his new grandchild, the company’s director of exploratory development, Victor Mills, suggested disposable diapers. After analyzing existing products and conducting consumer research, P&G created a dedicated diaper research group.

The research this group conducted, like that of its successors and competitors, wasn’t glamorous. It didn’t advance basic science. It wasn’t even an obvious route to profit. (One percent of the market!) It was a high-stakes gamble that required solving difficult engineering problems. How that happened represents the kind of hidden progress that leads to everyday abundance.

P&G’s first design flopped. Tested in the extreme heat of a Dallas summer, the pleated absorbent pad with plastic pants made babies miserable and left them with heat rashes. Starting over, the group had a one piece diaper ready for testing in March 1959. With an improved rayon moisture barrier between the baby and the absorbent tissue wadding, the new diaper was softer and more comfortable. An initial test of 37,000 hand-assembled prototypes went well, with about two thirds of the parents deeming the disposables as good or better than cloth. The next step was mass production.

Designing one well-functioning disposable was hard enough. Turning out hundreds a minute was practically impossible. ‘I think it was the most complex production operation the company had ever faced’, an engineer recalled.

There was no standard equipment. We had to design the entire production line from the ground up. It seemed a simple task to take three sheets of material – plastic back sheet, absorbent wadding, and water repellent top sheet – fold them in a zigzag pattern and glue them together. But glue applicators dripped glue. The wadding generated dust. Together they formed sticky balls and smears which fouled the equipment. The machinery could run only a few minutes before having to be shut down and cleaned.

Eventually, the diaper team mastered the process. In December 1961, Pampers went on the market in Peoria, Illinois. Once again, the test failed.

This time mothers liked the diapers. But the price was way too high for a single use item: ten cents a diaper, equivalent to about one dollar today. By contrast, diaper delivery services, which served about five percent of the market, charged no more than five cents a diaper. Home laundry costs ran to one or two cents.

Lowering the price of a diaper required much larger volumes. Aiming at about six cents a diaper, P&G engineers spent several years developing what Harvard Business School’s Michael E. Porter described as ‘a highly sophisticated block-long, continuous-process machine that could assemble diapers at speeds of up to a remarkable 400 a minute’. After successfully testing Pampers at 5.5 cents each, P&G began a national rollout in 1966. By 1973, disposables accounted for 42 percent of the US diaper market. [...]

The success of Pampers drew competitors into the growing market. ‘Any diaper maker that carved out a modest market share against Procter & Gamble could expect sales to triple as a result of sheer market growth’, write business historians Thomas Heinrich and Bob Batchelor in Kotex, Kleenex, Huggies, a history of Kimberly-Clark. But there was a catch. The bulky diapers took up so much space on shelves that stores rarely stocked more than two brands, plus maybe a discounted private label. Second place meant profits, third place disaster.

by Virginia Postrel, Works in Progress | Read more:
Image: A nurse demonstrating to young immigrant mothers how to diaper their babies: Israel Government (1950)