Sugru silicone-rubber adhesive sticks to its claims

Who hasn’t wished to strengthen the charging cord of a cellphone, tablet, or laptop that’s begun to fray? Sugru is a moldable putty made of silicone rubber, and repairing electronics is but one of the myriad uses suggested on its website. The product adheres to many surfaces, fills in gaps better than most glues, and sets in 30 minutes giving you time to make adjustments. Consumer Reports tested its claims and found it's as good as claimed—with just a few limitations.

From the Gaelic word súgradh, which means “play,” Sugru can bind to ceramics, glass, metal, wood, and most plastics and fabrics, according to its maker, FormFormForm Limited. (That wasn’t a typo.) It comes in 10 colors, but in the half hour you have before the putty gets too hard to mold, you can mix different-colored Sugru batches together to match, for example, the color of a chipped porcelain vase. Not that you can play to your heart’s content: It costs $12 for 3 packs, $22 for 8, and each pack holds 5 grams, an amount slightly less than a level teaspoon.

Sugru feels like Play-Doh while you’re working it. But once it cures, in about 24 hours, it behaves like what you might expect of silicone. It’s waterproof, will bend a bit, and can handle temperatures from sub-zero to about 350 degrees F. And though you might not be able to get it off a porous material, you can easily remove it from non-porous surfaces by cutting it or even simply rubbing it off.

How we tested

In our tests, we tried it out every way we could come up with. Our favorites included:

• Adding protective feet to items whose bottoms weren’t flat enough for adhesive-foam and similar store-bought pads;
• Making bumpers for the corners of a cellphone, adding protection and, due to the contrasting color, better visibility;
• Fixing items that needed a little extra support, such as a snapped microphone boom on gaming headsets;
• Filling in gaps caused by either missing pieces (a chipped ceramic container) or surfaces of different composition, which most adhesives won’t join.
  

What we found. As we expected, a pack doesn’t go very far. Sugru sticks adequately to non-porous surfaces but not as well as a true adhesive. It isn’t as soft as some other silicones once cured, and it’s not especially strong. And while you can compress it without problems, it didn’t handle stretching well.

Bottom line. We wouldn’t use Sugru where failure of the bond could create a safety or health issue. But in cases where filling a gap is essential, a structure requires some reinforcement, or surfaces don’t align well, we found it fun and useful—there are many situations where the usual adhesives wouldn’t apply. Still, we recommend it for non-critical repair tasks.

Need a traditional glue?

Our glue Ratings of nearly two dozen glues includes multipurpose adhesives, quick-set superglues, wood glues, and two-step epoxies. Be sure to read our glue buying guide before hitting the store.

—Ed Perratore (@EdPerratore on Twitter)