What Adhesive to Use for a Garden Mirror?

2 Materials
4 Hours

One day hubs came home with a curbside find that got me thinking about installing another mirror outside in our garden. Although the mirror glass had separated from the frame, both pieces were there and it could easily be remedied with some adhesive. But finding the right adhesive for outdoor use can be challenging so today we're passing our learnings along to you!

For the time being, I set the mirror aside;
what adhesive to use for a garden mirror
Hubs applied green painters tape around the inside of the frame (where the mirror will go) to protect from overspray, then painted the metal green.

Once dry, I removed the painters tape to prepare for adhering the mirror.
what adhesive to use for a garden mirror

In choosing an adhesive, I had several requirements: it had to be flexible at below freezing temperatures (so we could store it in the garage in the winter), weather-proof to stand up to rain and extremes in temperature (especially in the summer), and wouldn’t eat away at the mirror backing if it came into contact with it.

After researching my choices, I settled on not one but two adhesives. The first was  GE Silicone II to hold the mirror to the back of the frame and seal in the plastic backing.  GE Silicone II is what’s called a neutral cure silicone, meaning that it’s non-acidic (so shouldn’t harm the mirror backing) and is superior for outdoor applications. The only drawback is that it’s almost impossible to smooth it out nicely. That’s why I chose a different caulk to  seal around the front of the mirror.
what adhesive to use for a garden mirror
Although the main task of the second caulk was to seal the gap between the metal and glass on the front of the mirror, it also had to look flawless. I chose DAP Alex Plus. It’s an acrylic latex caulk that can easily be smoothed with a finger dipped in water for a neater seal around the front. We purchased a clear formulation; it’s goes on white but becomes clear as it cures in 7 – 14 days.

Installing Mirror into the Metal Frame

Clean the glass well so there’s no dirt to resist the caulk.
what adhesive to use for a garden mirror
Carefully scrape away any old caulk that still happens to be on the mirror.
what adhesive to use for a garden mirror
Starting with the GE Silicone II, cut off the tip of the tube of caulk on a 45 degree angle with a utility knife.
what adhesive to use for a garden mirror
Use a stiff wire that’s long enough to pierce through the seal; our caulk gun happened to have a piercing tool on it, so we used that.
what adhesive to use for a garden mirror
Put on disposable gloves. Load the tube into the caulk gun, depress it over a paper towel first to make sure you pierced the seal and the caulk is flowing. We actually didn’t pierce the tube on our first try and when I forced the caulk gun, the caulk exploded out the back end and oozed all over the gun. Oops! We were too busy cleaning to get pictures of the mess but lesson learned: if the caulk doesn’t flow easily, don’t force it – take the tube out of the gun and try piercing it again.

Start in one corner and run a bead around the perimeter of the mirror.
what adhesive to use for a garden mirror
Smooth it with a gloved finger to ensure it makes contact with the mirror and frame. It didn’t matter if I was messy with this step because we cut a piece of plastic backing to go over top. We let it set up only a few minutes so we could still press the backing into the silicone.
what adhesive to use for a garden mirror
We added a corrugated plastic backing (the same type of plastic that’s used as signage) to prevent the back of the mirror from being scratched from plant materials growing around it.

Set the plastic backing into place.
what adhesive to use for a garden mirror
Apply another bead of caulking around the plastic backing.
what adhesive to use for a garden mirror
Let it dry for a day, then flip it over. I put painters tape along the metal and also around the mirror, leaving a slight gap so the caulk could make contact with the mirror but be both neat and discreet. Here’s a closeup of the gaps we’ll be filling:
what adhesive to use for a garden mirror
I switched over to the Alex Plus, once again cutting the tip at a 45 degree angle and piercing through tip to puncture the seal. Since Alex Plus is latex, the bead can be smoothed with a finger dipped in water (no need to wear gloves this time). Use paper towels to wipe excess caulk off your finger as you smooth, and re-dip in water as necessary.
what adhesive to use for a garden mirror
Ensure all the gaps are filled (if not, got over it again and smooth before you lift the tape).

Let it sit for at least another 24 hours before hanging outside.

Although the GE Silicone II is rain ready after 30 minutes, Alex Plus takes 7 – 14 days to cure. For the first two weeks, if heavy rain is forecast, I plan to take both pieces down temporarily and store them in the garage so the Alex Plus has a chance to fully cure without being inundated with water. I don’t know if that’s really necessary, but I don’t want to take any chances.

We used vinyl covered hooks to hang the mirror on the fence. Look how beautifully the mirror reflects the rest of the garden – and our newly blossomed day lilies!
what adhesive to use for a garden mirror
Watch the brief video to see how we 'reflected on' this outdoor DIY!
The mirror wasn't the only thing we hung on the fence. Tune in next week to see what else we did and how we complemented our new outdoor mirror!

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Suggested materials:

  • Metal frame and mirror  (Roadside rescue)
  • Caulk  (Amazon or big box store)
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Want more details about this and other DIY projects? Check out my blog post!


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