What is the indirect method?
The indirect method - also known as the "reverse method" - is a technique where you do not glue the tiles directly onto the final surface. Instead, you first place them upside down on a temporary adhesive film. Only then is the entire mosaic transferred as a single unit to the surface.
The great advantage of this method is that your end result has a perfectly flat, even surface - all tiles are at exactly the same height. This is much more difficult to achieve with the direct method. Moreover, you can work comfortably at your workbench and only move the mosaic to the desired location at the very end.
This method requires a bit more preparation and patience than the direct method, but the result is more than worth that extra effort.
What do you need?
Before you begin, make sure everything is within reach:
For placing the tiles:
- Mosaic tiles of your choice
- A design/pattern printed on paper
- Adhesive film (self-adhesive transparent film)
- Masking tape
- A workboard
- A mosaic nipper (to cut tiles to size)
- Tweezers (for small or difficult-to-place tiles)
For gluing to the surface:
- Tile adhesive in powder form
- Water + a measuring cup
- A mixing bowl
- A spatula or palette knife
- A notched trowel
- Your final surface (e.g., MDF board)
- An extra small board for pressing down
- Wood glue or water-resistant glue (for loose tiles afterwards)
Step 1 - Secure the design to the workboard
Print your pattern at the desired size and place it on your workboard. Secure it firmly with masking tape on all sides so it cannot shift during work. Masking tape is ideal for this: it adheres well but leaves no traces on your work surface or design. Ensure your workboard is stable and flat - this is the foundation of everything.
Step 2 - Lay the film with the adhesive side up
Cut a piece of adhesive film that is slightly larger than your design - allow a margin of 1 to 2 cm on all sides. Lay the film with the adhesive side up on your design. Thanks to the transparency, you can clearly see the pattern through it, allowing you to place the tiles correctly.
Secure the film all around with a small piece of masking tape so it cannot curl or shift. This is now your work surface: the tiles will soon stick directly to the adhesive side of the film.
Step 3 - Lay the first tiles: start with the details
Now the actual mosaic work begins. Place the mosaic tiles with the good side (the beautiful, shiny side) down onto the film - the back is facing up. The tiles will stick to the adhesive film by themselves.
Always start with the details and contours of your design: the outline of the motif, small accents like an eye or beak, and only then the larger areas. Adjust tiles to size with the nipper if necessary. Work calmly and accurately - what you see now is the back, but the front that will be visible later is what counts!
Step 4 - Complete the full design and fill the background
Continue filling in the design. Cut tiles to size with the nipper where necessary for a nice fit. Once the main motif is completely finished, fill in the background - in this example, blue glass tiles around the bird.
Ensure uniform joints (gaps) between the tiles, and regularly check if everything fits the pattern underneath correctly. Take your time with this part: a carefully filled design makes the end result significantly more beautiful.
Step 5 - Stick the second film over the work
When all tiles are in place, it's time for a crucial step: stick a new piece of adhesive film over the top of the mosaic - the back of the tiles. Press the film down well so that all tiles are firmly secured.
You now have film on both sides of your mosaic. This ensures that everything stays in place during flipping and transporting.
Step 6 - Remove the bottom film and adjust the tiles
Carefully flip the work over so that the back of the tiles is facing up. Now slowly remove the original (bottom) film - the film you originally placed the tiles on. Pull it back carefully and flat, not upwards.
Afterwards, thoroughly check if all tiles are still positioned correctly. Have any tiles shifted or tilted? Use tweezers to accurately put them back in their correct place. This is your last chance to make corrections before the mosaic is permanently glued down.
Step 7 - Ready for the base
Your mosaic is now completely held together by the second film and ready to be glued to the final base. Lay the work and the MDF board next to each other so you have everything at hand for the next step. Also check if the base is the correct size and matches your mosaic well.
Step 8 - Prepare the supplies for gluing
Ensure all materials for gluing are ready: the mixing bowl, measuring cup with water, tile adhesive powder, spatula, and notched trowel. Also, place a sheet of paper or film on your work surface to keep the table clean.
Step 9 - Mix the water with the adhesive powder
Add the water to the adhesive powder in the mixing bowl - not the other way around, otherwise the powder is harder to dissolve without clumps. Stir well with the spatula until you get a smooth, homogeneous paste without clumps.
The correct consistency is similar to peanut butter: not too liquid but also not too stiff. Too thin adhesive bonds poorly; too thick adhesive is difficult to distribute evenly. Take your time to mix well.
Step 10 - Apply the adhesive to the base
Scoop a generous amount of tile adhesive onto your MDF base and distribute it evenly over the entire surface with the spatula. Ensure every corner and edge is covered - otherwise, the tiles will not bond well there later.
Step 11 - Use the notched trowel at 45 degrees
Take the notched trowel and hold it at a 45-degree angle relative to the base. Pull the trowel in straight, even lines over the adhesive to create a ribbed pattern and remove excess adhesive.
Those ridges are essential: they provide maximum adhesion between the tiles and the base. Work systematically and ensure an even layer over the entire surface.
Step 12 - Place the base onto the mosaic
Now carefully lay the base with the adhesive side down onto the mosaic. Do not press down immediately - position everything correctly first. Ensure the mosaic is nicely centered on the base. If necessary, slide the work into its correct place by carefully pulling on the film.
Step 13 - Carefully flip and press down well
Now carefully flip the whole thing over so that the mosaic lies on top with the beautiful side facing up. Then press firmly and evenly over the entire surface with both hands - or use the extra small board to distribute the pressure properly. Press down the middle as well as the edges and corners. This is decisive for a flat and sturdy end result.
Now let the work dry for at least 1 to a few days before proceeding.
Step 14 - Remove the final film
When the adhesive is fully cured, it's time to remove the last film. Start carefully in a corner and pull the film slowly and flat backwards - never pull upwards, as that risks pulling tiles off.
Hold the tiles down slightly with one hand while slowly pulling the film away with the other hand. Work patiently and methodically from one corner to the other.
Step 15 - Re-gluing loose tiles
It is perfectly normal for one or more tiles to come loose while removing the film. Don't panic! Simply glue them back in their correct place using wood glue (such as Collall or a similar product). Use tweezers for accurate placement.
The final result
After all these steps, you have a beautiful mosaic with a perfectly flat, professionally finished surface. The indirect method is distinguished precisely by that flat finish - all tiles are at exactly the same height, giving the work a sleek, high-quality look.
Your work is now ready to be grouted, hung, or set in mortar.
Tips & points of interest
- Work accurately when placing the tiles - errors are only visible after you have flipped everything over, so take your time at the start.
- The good side of the tiles always goes face down on the film - this is the most important principle of the indirect method.
- Use masking tape to secure your design and film - it adheres well but leaves no traces.
- Use enough adhesive on the base, but not too much - too much adhesive creeping between the joints makes it harder to grout later.
- Always pull the film flat and backwards, never upwards - this prevents tiles from coming loose.
- Allow sufficient drying time - the more patient you are in this step, the better the final result.
- For outdoors: always use frost-resistant mosaic tiles plus water-resistant tile adhesive and grout.
