How to Mosaic Tile A Mirror

I consider myself pretty handy when it comes to home improvement projects or crafty ventures. I get it from my Mama. There’s absolutely nothing the woman won’t figure out how to do.

So when I was invited to attend a class and learn how to to mosaic tile a mirror, I jumped at the opportunity to expand my DIY skill set.

Note: While the photos in this post are watermarked for another site (my old one) the content was updated in September 2023. This post also contains affiliate links.

Everything I needed to know to complete this project I learned in under an hour at a Home Depot’s Do-It-Herself workshop. Under an hour! That’s how easy this project is.

In total, the project took about 6 to 8 hours of work time over the span of a few days.

Because of the housing market crash in 2008, we felt stuck in that house. There were parts of it that I definitely didn’t like. Lots and lots of parts of it. Like the front bathroom. But it was our home, so my goal was to make it a place we loved being, which means lots and lots of home improvement.

After attending the DIH workshop, I grew a wild DIY hair and began talking Dan’s ears off about renovating the front bathroom. Starting with applying my newly developed skills and adding mosaic tile to the front bathroom mirror. Thankfully, he loves me despite my penchant for 11th hour DIY planning.

Step One: Gather Your Supplies

For this project, you’ll need mosaic tiles of your choice, adhesive tile mat, pre-mixed adhesive and grout, a sponge or two, a 150-grit sanding block, and some clean cloths. All of this cost me about $60 at my local home project store, but you can order from Amazon.

You will also need scissors or a box cutter, painter’s tape, a razor/scraper, access to water, either in a bucket or your bathroom sink, and patience.

Step Two: Cut Your Tiles

My bathroom mirror was 40 inches x 47 inches. Each mosaic tile sheet measured 12 x 12 inches. I used five sheets of tiles with extra tiles to spare. It’s always better to overestimate how many tile sheets you’ll need in case you encounter difficulty. You can always return any unopened tiles after the project is finished.

Using a box knife, I cut each of my tile sheets to the border size I wanted, which in my case was 3 inches. I extended the visual size of the mirror to 48 inches to match the length of the countertop.

SimpleMat comes in 9 x 18-inch sheets, so I cut several sheets into strips of just under 3 inches wide. I also cut two sheets into strops just under 2 inches wide to accommodate the edges I was extending.

Step Three: Prep Your Mirror

Make sure your mirror surface is clean and dry. The previous homeowners had glued a tiny frame to the surface of our mirror. Because it’s in a bathroom, the steam from showers caused the glue to unglue and the frame fell off.

I’m ashamed to say how long we lived with that ugly, glue-gooed mirror surface. While I kid wrangled, Dan scraped the glue off the mirror using a razor blade/scraper tool.

(You’ll also notice I changed the light fixture. Buh-bye ugliest box light I’ve ever seen in my life!)

Step Four: Sand Your Mirror’s Edge

Using your sanding block or sandpaper, rough up the outer edge of your mirror, just a little, being careful not to go further into the mirror’s center than you intend your frame to extend.

You just want to scuff the surface, which you can see in the upper portion of the above picture. (It’s really, REALLY hard to get a good shot of the scuff marks! Just a little. Promise!)

Step Five: Apply the Adhesive Tile Mat

I used a product called SimpleMat, but there are many, many similar products on the market now. Bonus, you can use adhesive tile matting on wall projects, too! Kitchen backsplash? Perfect! Adhesive tile matting eliminates the need for concrete or wooden backer board and for applying a layer of adhesive and raking it before applying the tile. Using adhesive tile mat easily cut this project time in half.

Cut your adhesive tile mat slightly smaller than the width of your tile strips. Peel the backing and apply the sticky side to the mirror’s clean, dry surface. Most adhesive strips are covered with a clear film that you’ll peel away before applying the tile.

Step Six: Apply Your Tile

Peel the clear film from the adhesive tile mat and apply your mosaic tile strips, working in small sections until you’ve covered the perimeter of your mirror.

I thought I would have 1/2-inch overhang on both sides of my mirror and ended up with almost a full 1 inch on each side which was fine because it actually looked better this way. To make sure the tiles that weren’t on the mirror would be sturdy, I used the pre-mixed tile adhesive and grout (hooray combination product!) to build a base behind the tile on either side of the mirror, as seen below.

Once the tile was in place, I used a plastic knife to scrape away excess grout that squished (technical term) out from behind the tile. Then I removed the painter’s tape and let the grout set while I watched tv.

Pro tip: It is strongly advised (by me, based on my own errors) that you lay out your tiles on your mirror before adhering them to double and triple check your measurements. I did not do this and ended up having to peel off part of the tiles, scrape off one entire side of tile mat, and then redo my work. Trust me on this. Lay them out before sticking them to the adhesive.

Grab a partner and hold your tiles up and mark on your mirror where the tile strips begin and end and mark which tile strip went where. This will also allow you to figure out if you’ve bought enough tile and arrange your strips to get a pattern you like, if you’re concerned with that. I didn’t want same-colored tiles touching across strips.

Step Seven: Apply the Grout

Applying grout is actually a multi-step process and you’ll have about 30 minutes per section before the grout begins to set and gets harder to wipe off. However, each section of the mirror took me about 15 minutes start to finish, for a total of 1 hour of grouting. It was the fastest and easiest part of the whole project.

Most people would use a tool called a grout float to do this step, but I just grabbed a latex glove and used my hand. I could feel and see what I was doing instead of just being able to see.  Tape off your wall and mirror and then begin.

First, you put the grout on the tile.

Next, you scrape off the excess:

Then, you wash down the tiles and grout until no grout remains on the tile, being sure to rinse your sponge frequently and change your water often.

This is where being in the bathroom came in handy. I just used the sink. (A commenter suggested this is not a great idea. Use a bucket with water you can dump and replace instead!)

You really want to make sure that you don’t leave grout film (which you can see on the tiles in the bottom left of the above picture) on the tiles. If you do, you’ll need to polish the tiles to get it off. So wipe with the sponge and rinse rinse rinse.

Then gently wipe with a clean cloth, microfiber works well, but I used a jersey cloth and paper towels and they both worked well, too.

Once your mirror is grouted, peel off your tape and leave the grout to dry. I went to bed right after finishing the grouting on Sunday night and everything was dry by Monday morning.

Step Eight: Admire your DIY Handiwork

You did it! You did it yourself! It looks amazing and you did that! That’s pretty awesome, right?

So now you can stare at the mirror and find reasons to go into your lesser-used bathroom to look at it. And maybe take 100 or so photos of your handiwork.

The actual final step in this process is sealing the grout. That will protect the grout from cracks and water damage. I gave the grout a few days to cure before applying the sealant, but I don’t know that several days are necessary.

After adding mosaic tile to the mirror, I tackled painting the ugly countertop and cabinet in that bathroom. By the time this renovation was done, the employees at my local Home Depot store probably knew me by name.

September 2023 update!

This house has been sold twice since we sold it, and the mirror is still going strong, over ten years later.

I definitely swiped this photo from the most recent real estate listing. The bathroom wall color and floor tile has been changed, and it looks like the cabinet and countertop may have been replaced, too.

But that mosaic tile mirror?

That’s all me.

If you do this tutorial, I hope you’ll let me know how it turned out for you! I’d love to see your finished projects!