Mounting A Mosaic On Clear Adhesive Film

Clear contact paper can be used to temporarily mount a design of mosaic tile, but it really isn’t sticky enough to be as useful as it should be, and it is better to use the clear mosaic mounting tapes (films) that are specifically designed for that purpose. I have used clear contact paper for small mosaics (less than 1 square foot), but even with something that small and simple, there were problems with tiles falling off and moving around when the sheet was pressed into the mortar. Mosaic mounting tapes have strong but removable adhesives. They are available in 3″ widths, 6″ widths and 12″ widths, but you can always overlap narrow tape to temporarily mount a mosaic of any width.

TIP: Save money and buy the 3″ width and just overlap it slightly to get whatever width you need. Remember, the pro-grade tape only comes in rolls 108-feet long. Sure, you can buy shorter rolls elsewhere but it isn’t the same tape. How much money did you save if the tile moves on the tape while you are mounting it in mortar and you screw up the mosaic?

Note that clear contact paper is still used in the method explained below, but it only serves to keep the tiles from moving around while you apply the clear mounting tape.


The paper pattern is taped down to the work surface and clear contact paper is taped STICKY SIDE UP over that. The purpose of the contact paper is to keep the tile from moving around after you position them. After all the tile has been placed, the top of the mosaic design is covered in clear mosaic mounting tape, which is much stronger than contact paper.

Instructions for Using Clear Mosaic Mounting Tape

1. Tape or tack your paper mosaic pattern to your work table.

2. Tape or tack clear contact paper upside down on top your paper mosaic pattern with the sticky side facing up.

3. Position your tile on the pattern, sticking the bottoms of the tile to the sticky contact paper.

4. After all of your tile is in place, cover the top of the mosaic with clear mosaic mounting tape.

5. If your mosaic is larger than a square foot or two, then use a box cutter to cut the mosaic into manageable sections.

Note that sections you cut in step 5 do not have to be squares. Unless you are shipping the sheets to a client for installation by a contractor, there is no need try get them into roughly even squares. Instead, it makes more sense to divide the mosaic in places that make it easiest to line the sheets up when they are permanently mounted in mortar or adhesive.

Advantages of This Method

Using clear mounting tape has several advantages, and they are each significant:

  1. It allows you to work with the tile and the mosaic in progress FACE UP.
  2. The temporarily mounted mosaic is still visible through the clear mounting tape, which can be very important for lining up the sheets when you press them into thinset. A perfectly executed mosaic can be permanently flawed if an installer leaves a slightly extra wide gap between sheets.
  3. There is no mounting mesh involved, and thus the tile can be pressed directly into thinset mortar for maximum life outdoors and in wet locations. Mesh requires an adhesive be used to attach it to the tile, and that is a point of vulnerability, and Achilles heal that moisture could penetrate and delaminate over time.

Expensive Mounting Tape Is Actually Cheap

A 100-foot roll of mounting tape currently sells at our website for either $70.31 or $135.52 depending on whether you get the 6-inch width or the 12-inch width. Now that might be a little steep for a small project at home or maybe even a mosaic for a client that you happen to be installing yourself. But consider the following scenario: You have been commissioned by a high-end hotel or casino to make a 50 square foot mosaic to be installed behind their bar. The mosaic is highly detailed, possibly even photo-realistic, and it is made from several thousand dollars of smalti, and you have spent three or four months making it.

Do you really want to risk having their installer accidentally getting irregular widths between sheets? If you use opaque mosaic mounting paper, then the problem will not be discovered until the mortar has hardened and permanently set.

“Professional Installers”

A word about “professional installers” and other contractors: I have received more than a few emails over the years from high-end architectural jobs in places like NYC and LA where “professional installers” have done things like press sheets of tile PAPER-FIRST (I kid you not) into thinset and similar bonehead goofs. If all your “professional installer” has done is install 4-inch glazed ceramic tile in bathrooms, it doesn’t matter how many years of “professional” experience they have.

If you have to involve a contractor in your mosaic art project, don’t be surprised if you have to talk to a few before you find someone with relevant experience or even basic competence. In my experience, this is true of many aspects of home renovation, but it is particularly true of mosaic. Many contractors claiming to know something of mosaic have actually done only basic tiling using the materials and methods relevant to larger glazed ceramic tile.

41 thoughts on “Mounting A Mosaic On Clear Adhesive Film

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  5. Renee

    Thank you for your informative article. I had a mosaic mounted to the adhesive tape and a piece broke. I had one heck of a time getting it off the tape and now I’m afraid to mount it for fear I won’t be able to get the tape off after mortaring it to the wall. Is there a trick for removing the tape once the project is mortared?

    1. Joe Moorman Post author

      Pull the tape off by pulling parallel to the surface of the mosaic instead of out from the surface of the mosaic.
      I hope this helps.

  6. Sherri Grasmuck

    Hey Joe,
    This sounds intriguing and seemingly easier than using wellbond to glue directly to the mesh. You mention every step in the mosaic transfer process using tape here except what happens to the contact paper? Obviously it has to come off before you press it into thinset but I am wondering how easily that happens? It would seem that just pulling it off after you have turned it over would also pull off the tiles. What am I missing?

    1. Joe Moorman Post author

      Hi Sherri,

      The use of contact paper is based on the fact that it isn’t very sticky. We don’t use it to pick tiles up but rather to keep them from moving around on the pattern while we apply the mounting tape or paper to the tops of the tiles. Then we lift the sheets off the contact paper.

      If you are using mounting mesh, then you don’t need the sticky contact paper sticky side up. In that case, you would put it over your paper pattern sticky side down to protect the pattern and keep glue from sticking to it. Then you would lay mesh over the top of this protected pattern, and then you would glue tiles to it.


      1. Andrea Lombardo

        Is there a brand of contact paper you suggest? I am so worried that it is so sticky I won’t be able to lift the tiles off. Besides that, I am new to mosaics and have only done 4 (experimental) pieces. The next one will be “for real” and want to makes sure, as best I can, that I do it correctly.
        Thank you

        1. Joe Moorman Post author

          Hi Andrea,

          We use the original Con-Tact brand that seems to have nearly all of the market share. It is just barely sticky enough to keep the tiles from moving around.

        2. Louise Roberts

          I have used the regular brand Con-Tac paper and it works great. It is easy to remove but sticky enough to hold the tiles in place while you are putting your piece together.

  7. Brad Roberts

    I have glass tile on film that I’m about to install. The back side without the film are different heights and curved shapes. The side with the film a semetrical flat 1/2″ tiles. When installed, should all the tiles be smith or will some be raised?
    PS. I actually like the look of the back.
    PSS. No manufacturer information known.

    1. Joe Moorman Post author

      Hi Brad,
      The embossed face is the back. Those ridges and bumps help the cement grip the tile. The flat side under the tape is the face of the tiles.

  8. Steve

    is this the same 5.5mm tape I see on other sites for a lower price or is it a heavier tape?. How thick is the tape? Who is the manufacturer?

    1. Joe Moorman Post author

      Hi Steve,

      All I know about our tape is that it was chosen base on it’s reliable hold and ease of use compared to other tapes. I bought it from a supplier who produces custom-made mosaics. Thanks.

  9. Stacy Koss

    Hi Joe

    I came here because I was reading the article about “Fish Shower Mosaic by Jen Vollmer” and it spoke about different thicknesses of glass and tile in the same mosaic. I have just started a kitchen backsplash mosaic and this situation is exactly what I am dealing with. I am using sticky mesh for the mosaic and what will be the ‘backdrop’ of the mosaic is Mother of Pearl subway pieces which are about half the thickness of the glass……ugh….should I use the mosaic tape to raise the Mother of Pearl to the height of the glass? My goal is to have the Mother of Pearl shell and the glass to be the same height.
    Not sure how I’m going to do this…… help!! Thx

    1. Joe Moorman Post author

      Hi Stacy,

      All is not lost! I wrote and article about how to build up areas for mosaic insets between thicker tiles or borders.

      In your case, the height needed to be built up is probably small, and so you could probably use plain thinset mortar with no extra fillers to build up the area. However, thinset contracts or “thins” during the first 3 days or so of the curing process, and so you would want to build the area up at least 3 days before using more thinset to mount the tiles.

      If you build the area up, but it contracts more than you want, then you can add more thinset when you mount the tiles. That is preferred to building the area up too much and then having great difficulty in scraping it down.

      Do some experiments on a scrap piece of plywood before you do the project so that you can work out how much to put down and how much it contracts.

      I hope this helps!

  10. Louise Roberts

    You suggest using thinnest instead of grout because “It is better to use more thinset instead of grout because it will match the color of any thinset that pressed up between the tiles when you mounted the mosaic.” Does this hold true for a mosaic that will be outdoors, or is it better to use sanded grout?

    1. Joe Moorman Post author

      Either thinset or grout would be good for grouting the outdoor project. The advantage of grout is that you can buy a custom color.

  11. Louise Roberts

    I am making a mosaic to hang outside. You suggest to use thinnest rather than grout. “It is better to use more thinset instead of grout because it will match the color of any thinset that pressed up between the tiles when you mounted the mosaic. ” Does this hold true for an outdoor project or it is better to use sanded grout?

    1. Joe Moorman Post author

      Either thinset or grout would be good for grouting the outdoor project. The advantage of grout is that you can buy a custom color.

  12. Diane

    Once you press the tiles into the thin-set, how long do you leave the mosaic tape in place before removing?

    1. Joe Moorman Post author

      I like to wait 2 days, but most people pull it off in 24 hours. I pull the sheet off at 180 degrees (backwards) and not 90 degrees (straight out) to minimize the force pulling the tile out of the mortar. Peel the edge of the tape up and then pull or roll it backwards instead of pulling it straight out from the wall like you are trying to make a tile come loose. I hope that makes sense.

  13. Allie

    Can I use mesh (I just bought recently from your site) for my outdoor project? I am mosaic-ing part of my chimney. I was planning to use thinset to adhere it to the mesh while I put my design together and then use more thinset to adhere the assembled mosaic (attached to the mesh) to my chimney when I bring it outside.

  14. Carol Lanigan

    Just used tile tape for the first time. Wonderful stuff. Doing glass on glass so I don’t want to use thin set but silicon adhesive instead. Wondering how thick the silicon needs to be to insure adhesion. Thanks for the informative tips.

    1. Joe Moorman Post author

      Hi Carol,

      The silicone doesn’t have to be too thick, but you want to make sure you don’t press the tile down so firmly that you press all the silicone out from beneath the tile. This is particularly important if the tile doesn’t have ridges on the bottom and is perfectly flat.

      All that being said, you don’t want it so thick that it can be compressed like rubber after it hardens. You also don’t want it so thick that the excess squeezes out and fills the grout gap.

      As always, a few quick experiments with a few pieces of scrap can save you much time and stress in the long run. The exact thickness to put it on can depend somewhat on the size of the tesserae, but I would shoot for 1/16 to 1/8 inch as a starting point.

      I hope this helps!

  15. Rachel Wells

    I am making stained glass mosaic lampshades. Some of the glass I mosaic is glass gems, some beach glass , many are beautiful expensive agate slices, and stained tumbled glass. I love the changing heights of the glass and the different angles and the way the light is refracted from the different surfaces.
    Sometimes I am gluing onto white glass cone shades (using Zap-a-Gap) and sometimes the base shades are plastic.( using Gorilla Silicone Glue)
    I have 2 problems …#1: with the black grout pitting in the glass and agate #2: with the grout cracking.
    It is sanded grout…
    The grout lines are different dimensions and the depth of the grout is not all that regular either.
    I want to improve.

    1. Joe Moorman Post author

      Hi Rachel,

      Plastic can flex slightly, and even though it is imperceptible, it is enough to crack grout. Grout can also crack if you add too much or too little water. Grout should be the consistency of wet dough when applied.

      Grout release from a building material store can be used to prevent staining.

      It takes some “finger grouting” with a gloved hand to grout a mosaic made of different thickness.


  16. Barbie Paulsen

    I made a mosaic using the ConTac paper technique. I have cut the 3′ wide x 7.5′ tall finished mosaic into pieces about 1 foot x 3 feet for transportation to the house where it will be installed (our retirement home). It is going in the large, walk in shower.

    I have some questions about the installation, which I plan to do myself:
    – How small should I make the pieces of the mural before putting them on the wall?
    – How thick should I make the thinset? (I want it as thin as possible for reasons I’ll explain below.)
    – Is it okay to smooth the thinset flat before pressing the mosaic in place? Some of the pieces are smaller than the ridges on the thinset tool and I worry that mortar will squish up and fill the spaces where I want grout to be.
    – What mistakes do I not realize I’m making?

    I’ve put a link to my facebook album of my progress in the place where the form says “website” so that Joe can have an idea of what his tutorials have inspired. The last mosaic I did before this was a 1 foot square project with my mom over 50 years ago.

    1. Joe Moorman Post author

      Hi Barbie,

      Nice work! I love herons. That is a solid composition and a carefully planned execution. The cartoon and concept sketch are so well done that it looks like you were making this project for a tutorial!

      Most people cut up the mosaic into sheets roughly 1 square foot. The biggest tip I could give you is to make sure that the grout gap between sheets is the same as the gap within the sheets.

      Please email me pics of that project.

      The product description for the Notched Trowel explains about spreading and smoothing thinset mortar.


  17. Sue

    Hi, all of your posts have had great information since I also work in stained glass using the reverse method. To keep the thinset from coming up between the tiles I lflip it over and apply grout to fill in a very thin skim, just to fill the areas between the tiles. This is when the grout color will be different than the thinset. (Got the method from Carl & Sandra Bryant, Showcase Mosaics)

    What I though was to experiment with is coloring the thinset with powder pigments to skip this step.
    Have you tinted thinset due to a big color difference from the grout?
    What thinset do you recommend to adhere glass to exterior cinder block walls?
    The summer heat in Tucson AZ is extreme.

    1. Joe Moorman Post author

      Hi Sue,

      I use Versabond thinset mortar for exterior mosaics, and have dyed it with liquid concrete dye. I would make sure that the cinder block wall has been saturated with water by spraying with a hose. I let the surface dry, but I want the interior of the porous backer to be saturated with water and to not function as a reservoir of “dryness” that sucks the moisture out of the thinset before it can harden.

  18. Kathy Maguire

    I have just found your site and so happy I did. Lots of great information. I’ve been reading your blogs, and am still a little unsure of how to go about my next project. I am an amateur artist and am just learning mosaics. I’ve only done 2 inside pieces (with wood backing), but have been very happy with the results. For my next piece, I want to do a circular plaque (17″ diameter) to hang between my garage doors. Design will be a stylized sun/American flag. But I know the substrate and adhesive have to be considered carefully for it to have any chance of longevity. I need something lightweight and have read about “wedi” board. Is this anything you would recommend? Any advice from substrate, to adhesive, to final finish would be appreciated. I plan to do this in glass. Thank you!

    1. Joe Moorman Post author

      Thinset mortar is used for outdoor and wet mosaics.

      Foam-core tile backer boards include Durock, Schluter Kerdi Board, Laticrete Hydroban Board, Johns Manville GoBoard, and Wedi Board.

      Outdoor mosaics can be executed on Hardiebacker, which is stronger than regular concrete board. The edges are not crumbly like regular concrete board. The manufacturer doesn’t recommend it for outdoor use because it contains cellulose fibers, which is potential food for mold.

      The key to making it work is to paint the side edges and bottom with multiple coats of outdoor paint (oil-based) after the mosaic is finished.

      Of course you should seal the finished mosaic with multiple applications of a tile and grout sealer.

  19. Sophia Di-Mascio

    Just stumbled across this brilliantly insightful forum, thank you Joe.
    I am an artist mostly doing Silk chinoiserie wallpaper and am now very excited to be trying mosaics on a bathroom wall mural. First question is how to transfer the design – looks like the clear transfer film is the right product. I just want to double check that this is not ‘so strong’ that it risks pulling the small
    Mosaics out even if removed at 180 degree angle?
    I tried to look for the dissolvable paper backing that commercial mosaic sheets come with but have failed thus far!
    Secondly, I am planning to use a combination of smashed marble pieces (10mm) with smashed geode and quartz slices – no idea if it will
    Work but if you’ve had experience with this material please let me know – very open to tips!!
    They are about 3-4 mm different in widths but I think you’ve already answered questions on building up the mortar so I’ll check that again.

    Thanks so much in advance for any advice you can give me!



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