How Effective Is Flex Glue? Inside Edition Puts 'As Seen on TV' Adhesive to the Test

Is Flex Glue as strong as the TV commercials make it seem? Inside Edition found out.

The Flex Glue commercial looks incredible: A super strong adhesive that can do it all.

TV ads show Flex Glue holding weights of more than 1,000 pounds, working underwater and even keeping an entire 4x4 vehicle together.

But is it as good as it appears?

Inside Edition went to the Grove School of Engineering in New York City to get some help from two professors, chemical engineer Raymond Tu and mechanical engineer Ali Sadegh.

First, they carried out the cinder block test. In the commercial, the glue instantly holds the cinder blocks together as the host lifts them up.

We had Professor Tu glue the cinder blocks together with Flex Glue and then enlisted the help of a body builder to lift them up. On the first try, it didn’t work.

"Uh oh," said Inside Edition’s chief investigative correspondent, Lisa Guerrero. “That didn’t work as it did in the commercial.”

The second time, they used a little more glue and applied additional pressure.

"This time it held," said Guerrero.

Next up: 1,000-pound weights. In the commercial, they glue two blocks of wood together and then attach 1,000-pound weights. But if you look at the fine print, it says you’re supposed to let it dry for a full week.

Amazingly, when Inside Edition put it to the test, it held — on the first try.

“Wow, it’s holding!” Guerrero exclaimed.

But perhaps the most incredible claim in the commercial is video of a dune buggy held together with Flex Glue.

Inside Edition bought our own buggy, then enlisted students and faculty members to help glue the parts together.

The team then took it to an off-road track, where Guerrero gave it a go.

"So far it’s holding up," she said. "It’s not breaking."

Then professional race car driver Jason Rabe took over and gave the buggy an even rougher ride.

First one bar came loose, then another — not at all like the commercial.

"This did not hold up," Guerrero said.

The makers of Flex Glue said we should have waited for the glue to dry for an entire week before carrying out the test. So Inside Edition glued it again and waited a week, but the same parts came loose.

"Overall the glue is a very impressive product," Professor Tu said. "But the experiment they show on TV really pushed  the envelope on what the glue can do.”

UPDATE: After Inside Edition's report aired, the makers of Flex Glue sent the following video response: