It sounds goofy. A window film that thwarts thieves?

Certainly, say 3M officials, who recently applied the company's storied history with adhesive window films to automobiles.

The Maplewood-based company launched its 3M Scotchshield Automotive Security Film at NASCAR races in California last weekend and found lots of interest. The film keeps car windows intact, even when shattered by a heavy object.

A filmed window will break, but the clear adhesive film holds glass fragments in place, making it much harder to crack a hole in a car window.

It's a "deterrent to smash-and-grab crimes," said Karen Martin, 3M automotive marketing supervisor for the United States.

To determine interest, 3M researched cities in Brazil, Panama, Mexico and the United States that are plagued with property thefts from autos and with auto theft. Researchers found thieves use hammers and crowbars to bust car windows so they can snatch laptops, GPS devices and other items from seats and dashboards, Martin said.

Armed with that information, 3M went to work. It found that with the film, car windows will "eventually break. But it will certainly take a lot longer to break into the car. It could take many minutes. Without the film, it takes about 3 seconds," Martin said.

The idea for the auto window film is similar to that for existing 3M films that are used to make building windows resistant to damage from hurricane winds.

But the transition from buildings to autos was no easy feat. It took a year of research, thousands of dollars and a team of scientists, security consultants, testers and marketers to make an effective security film that worked.

"We have not had [a security film] automotive application before because you have to shrink the film so that it fits a curved glass. Yet we still needed it to be strong. So this has been a little trickier," said Martin, adding that it's been an obstacle for competing products as well.

The $30 billion conglomerate long has made tinted auto films that cut glare from the sun and block UV rays. Thirty years ago, 3M first gained national attention for making films for residential windows that keep out the cold.

Now it's moving to battle more-frightening foes. To make sure it got it right, 3M called in Architectural Testing Inc. and attacked its 3M prototype with heavy dumbbells and hammers to make sure it was sturdy enough to carry the "security film" label.

The new product is being showcased at NASCAR events, the Specialty Equipment Manufacturers Association (SEMA) auto products show, and other conventions and trade shows.

The product is expected to help 3M's existing window film unit grow, said 3M officials who declined to provide sales targets. The new product line will be part of 3M's $5.7 billion Electronics and Energy Business Group and will be marketed globally.

Customers can expect to shell out a few hundred dollars to buy the window films and have them professionally installed, Martin said.

In the meantime, expect major marketing as 3M gets the word out. 3M noted that the National Insurance Crime Bureau estimates that a car is stolen every 33 minutes in the United States, costing $6.4 billion a year. While 3M's new security film won't scare off every thief, it can slow thieves down, call attention to their deeds and perhaps make them want to move along quickly, officials said.

Dee DePass • 612-673-7725