Charmin spent five years and 30 patents on wavy perforations to end the incomplete tear

Slate's Dan Kois noticed scalloped edges on his Charmin Ultra Soft and, in a Zoom interview, P&G senior scientist Gregg Weaver told him they were no aesthetic flourish: the company was rolling out Smooth Tear to solve the incomplete tear, which Weaver says is the top complaint on Charmin's call-center lines. Five years and 30 patents went into it, he says.

Weaver says the team began with causes. Toilet paper fibers mostly run vertically, so tearing across means tearing against the grain, and people vary by hand, roll position and over- or under-roll, but most tear in a downward diagonal rather than straight. Scientists hand-punched perforations into blank rolls to find the right shape; a diagonal line matching the average angle worked on one side but not the other, while a wavy line best withstood the mix of forces. Testers, he says, said it 'tears like a hot knife through butter'.

Most of the five years went on production. Straight perforations at a 90-degree angle are ideal for machines running paper at 60 miles per hour, a design Weaver says dates back about 100 years, so P&G had to change and replace the perforation machines across its six toilet-paper factories. For now it is only on Charmin Ultra Soft. Kois says he saw little difference in his own tear rate, but liked the curvy edge.

The complaint was specific and measurable: incomplete tears top the call-center log.

The cause was physical: grain direction plus the diagonal pull people actually use.

Testing shapes by hand on blank rolls was cheap enough to try a diagonal first, then a wave.

Straight lines were a factory convenience, so changing the shape meant changing the machines.

Fix the complaint at its physical cause, then accept the manufacturing cost: the factory retooling, not the idea, took most of the years.

Smooth Tear was officially rolling out as of Kois's October 2023 piece. The scalloped rolls had been appearing in stores for about a year before P&G explained them. The column reports no data on complaint rates after the change.