Mirror adhesive: weight, adhesion and the install at the end of EP1

The last minutes of Arena do Vidro EP1 were all assembly. The Hello Kitty mirror was already cut, sandblasted and edged. What was left was mounting the LED, the touch button and the hanging system. And I announced the rule: the mirror was going up on the wall. "If it falls, you're out."

That's when the panel gave one of the most useful pieces of advice in the episode, about mirror adhesive. It applies to any job, not just a reality show. In this post I put together what the judges said and what each contestant did when it came time to mount.

Every adhesive has a weight rating

One judge explained the basics many people skip: each adhesive, depending on its type, holds a certain weight. That information is in the manufacturer's spec, in the instructions. Before deciding whether an adhesive will hold, check that the mirror is within its weight rating.

Dirty surface: it can hold the weight and still not stick

The second part of the explanation is what brings mirrors down in real life. Any sealant or adhesive you use needs a clean surface. In the Arena, with sandblasting going on next to it, there was a lot of dust. So even if the adhesive can hold the weight, it won't bond, because the surface is contaminated.

The panel's advice was simple: clean it well and go ahead. Once it's clean, and within the weight spec, the adhesive holds. In a glass shop that applies to the back of the mirror and to the wall: blasting dust, edging dust, construction dust, grease from your hands. All of that ends up between the adhesive and the surface.

The button, curing time and super glue

Showing his work, one contestant explained what he does day to day. The touch button comes with its own adhesive. And after gluing the mirror, he runs mirror adhesive around it to lock the piece in place while it cures. The glue hasn't cured yet, but the mirror doesn't move.

The hanger was another story. He used super glue, and admitted he was out of his comfort zone: day to day, he always uses an MDF cleat. When someone asked him, in Spanish, why he didn't use the MDF, his answer was honest: he was afraid the super glue wouldn't hold. In other words, when you swap your mounting system for one you don't know, even choosing the adhesive gets shaky.

A hanger designed with the installer in mind

The other contestant picked a hanging system thinking about whoever installs it. As he explained, it's more practical: you don't waste time hunting for the screw when positioning it, and if it ends up off-level you can add something inside to level it. "Time out there is money." On the LED, he admitted that with more time he'd have run another strip around an inside curve for better lighting.

Mirror mounting checklist

• Check the adhesive's weight rating in the instructions and weigh the mirror.
• Clean the back of the mirror and the wall: no dust, no grease.
• Use an adhesive made for mirrors; the wrong sealant can attack the mirror backing.
• Lock the piece in place while the adhesive cures, like the contestant who runs mirror adhesive around it.
• Stick with the hanging system you know. Switching systems in a rush breeds doubt.
• Think of the installer: a system that makes positioning and leveling easy saves time on the job.

How much weight can mirror adhesive hold?

It depends on the adhesive. As one judge explained in EP1, each has a weight rating in the manufacturer's spec. Check the instructions and weigh the mirror before deciding.

Why didn't a strong adhesive hold?

Because the surface was dirty. With dust, the adhesive can be rated for the weight and still not bond. The panel's advice was to clean thoroughly before gluing.

How do you keep a mirror from shifting while the adhesive cures?

Lock it in place during curing. One contestant said that, day to day, he runs mirror adhesive around the edge so the mirror stays put.

The full EP1 is on the episode page. If none of your mirrors has ever come off a wall, applications for the next Arena season are open here on the site.

Full episode 1 · Dust-free mirror sandblasting · How to edge a curved mirror without breaking it

Episode 1