What do I do with this big honkin' mirror?
April 2, 2015 11:17 AM   Subscribe

When we bought our new (to us) house, we discovered that the previous owner had left a big slab of mirror in the attic. As we don't have a big mirror anywhere in the house, I would like to frame it and hang it, but... I am having a hard time working this out. The mirror measures 76" tall, 36" wide, and is about 3/16" in thickness. More within.

My original plan was the cut a piece of 3/4" finished plywood to 80" x 40", gluing the mirror to the center with a 2 inch gap on all sides, and use baseboard to build a frame around it. The baseboard would have 2 inches of plywood to connect to, plus cover about 1 1/4 inch of the mirror (hiding some of the damage around the edges. On the back, I would make a couple of french cleats using 1x4, screwing into the plywood from the mirror side (before gluing the mirror on, obviously) and into two studs in the wall.

My main issue is that I don't know how to fill the 3/16" difference that will exist on the 2" plywood "border" and the face of the mirror so that the frame will lay flat. I could cut the plywood to fit the mirror exactly and then just glue the entire baseboard moulding to the mirror face, but that eats up a lot of mirror and, frankly, I think it would look like shit.

Everything that I can find online seems to involve building an elaborate frame around an existing hanging mirror or building a simple frame for a tiny picture-sized mirror. This is the best tutorial that I've found, but it's for a fairly smaller/lighter mirror than my own, so I'm pretty set on the french cleat idea. My walls are lath & plaster, if that matters.

If someone has a resolution to my issue, or even a better idea of what to do with our mirror, please say so.
posted by JimBJ9 to Home & Garden (8 answers total) 3 users marked this as a favorite
Assuming you're trying to avoid milling a recess into the back of the baseboard (can't find a place to use a router table for a little bit...):

How about cutting a 3/16" spacer out of masonite, and then getting another piece of pre-shaped moulding that's 1" + the thickness of the mounding - 1/16" and gluing it around the outside of the whole thing? That much thicker on the border, but also hides the edge of the plywood.

I'm assuming you're going to cut your miters by hand and fill the resulting gaps with putty or painter's caulk?
posted by straw at 11:28 AM on April 2, 2015

If it were me, I'd build the heck out of a wood back using solid wood boards, with little shelflets (just big enough to hold the mirror) maybe 5-6" in from either end of the bottom edge, leaving a gap in the bottom supporting edge (see below), and also adding edge stops on the side and top to keep the mirror in place. Then pilot hole & _screw on_ a front frame - made from flat but thick and _solid_ molding, or just plain 1 x 3 with routed edges - onto the front, using countersunk holes, covering the screws and holes with wood filler. This could look clunky, but if you do it right it doesn't have to.

Why so extreme? Mirrors are heavy. Also I hate plywood, but mainly the weight issue: solid wood will hold your fasteners well, and if you make a back frame out of just boards, you can leave big gaps, ultimately using less wood and adding less weight. Also, you should be able to design something that will be easier to hold onto than a big flat rectangle.

Why the shelflets instead of a complete bottom edge shelf for the mirror to rest on? You clean a mirror with a squeegee, or with liquid that inevitably runs down to the bottom -- and that same liquid will corrode the back. This way, you can wipe most of the bottom of the mirror by running a dry cloth underneath, so that the back won't corrode from leftover cleaning liquid.

Now you've inspired me. I happen to have a large mirror too!
posted by amtho at 11:40 AM on April 2, 2015 [2 favorites]

Use a stair edge for laminate flooring as your moulding around the mirror. They come in assorted solid woods stained assorted colors and they already have a rabet in the back that would fit over your mirror.
posted by Mitheral at 12:13 PM on April 2, 2015

I'd say don't glue mirror to plywood--differential expansion may crack mirror.

Maybe make a frame from 1 x4 oak or cherry with pocket screw joinery. Pretty strong and no miters. You could glue and screw french cleats to the frame sides, top and bottom. Of course, you would need to be able to rabbet for the mirror.

Thicker edging could disguise additional thickness of french cleats.
posted by H21 at 12:49 PM on April 2, 2015

A 76 inch high mirror would look pretty amazing just propped against a wall.

Have you looked into using crown instead of baseboard moulding? We've done several pictures and mirrors using crown and the results have always been pretty impressive.
posted by the webmistress at 1:07 PM on April 2, 2015

I have done almost exactly this, with the added challenge that my mirror is beveled. Let me dig up my SketchUp files and get back to you.
posted by nicwolff at 1:12 PM on April 2, 2015

The adhesive to use is a product called "mirror mastic".
posted by nicwolff at 1:13 PM on April 2, 2015

Here is a PDF with a cross-section of my solution. You can see the beveled mirror, the ½" plywood it's stuck to, the ¼" spacer that surrounds it, the molding that those are screwed to, and the ¾" legs that are screwed to that. I'll post a picture of the result when I'm home.
posted by nicwolff at 8:48 PM on April 2, 2015

« Older Best way to get a driver's license in Ontario?   |   I WON'T AND YOU CAN'T MAKE ME Newer »
This thread is closed to new comments.