March 31, 2008

DIY Nightmare: Why Stripping Wallpaper Is a Mess

You grip. You tug. It rips. Will that blasted piece of wallpaper ever come off cleanly?

New research shows the do-it-yourself crowd may just be out of luck when it comes to removing any sticky sheet such as tape or wallpaper.
In fact, pulling evenly on an adhesive
pretty much guarantees it will end, frustratingly, in a triangular point,
scientists say.

"There's basically no way to get around it," Pedro
Reis, an applied mathematician at MIT, told LiveScience. "These are
the cards the laws of physics have dealt us."

Reis and his colleagues in France and Chile detail their work on the tricky, sticky phenomenon in the March 30 advance online
issue of the journal Nature Materials.

Deformed film

When a strip of something
is yanked, Reis said, the force not only works to break the
adhesive's grip, but also deforms two folds from which the piece originates.
Somehow, that deformity always causes the strip to narrow into a point.

"The geometry of how the folds deform is extremely
important," Reis said. "If you get rid of the adhesive properties of
a film, though, then our theory doesn't apply."

The strength of an adhesive, the thickness of the sheet and
the force it's being pulled at, he said, are key to determining just how
quickly an attempt at redecorating will devolve into a frustrating triangular

A robotic film-pulling experiment the team designed showed
that slower pulling lowers the adhesive's strength, reduces the deformation at
the strip's folds, and ultimately yields a longer yet still triangle-tipped

"The moral of the story is 'go slow,'" Reis said.

Sticky applications

Reis expects his research to extend into the field of bendable

"This is helpful information in designing anything that
has adhesive properties," Reis said of the research. "If you're making
stretchable electronic circuits, you're depositing metals onto a thin
polymer sheet
. You want to know the limits of the material you're depositing
on, and this could help."

Wallpaper manufacturers could also learn a lesson or two, he

duct tape, it has a mesh in it to prevent the deformation, so you always get a
perfect rectangular strip," he said. "Maybe they should put a mesh in
wallpaper from now on."