How to Make Your Own Backer out of Fabrics
Turning simple objects into mosaic backers is really a lot of fun. My first experience with this was my "Gone Fishing" hat. I bought a cotton fishing hat and made it into a hard base to mosaic on. Now I've decided to create two other different backers using a towel.
First and most importantly, since you will be mixing powdered thinset, I recommend you use a dust mask and work in a very well ventilated room. You might also consider wearing gloves, but if you don't, know that thinset is a drying agent for your skin, so just wash your hands frequently and apply hand lotion and you'll be fine.
I chose 2 terrycloth white towels to be mosaic bases. Then I set up my workspace by putting down brown paper and then a board over it, knowing this is a very messy project and the board and paper will be tossed out when done. The board is a good surface to work on, as you will be manipulating the towel and need a sturdy surface.
Next, you'll need to have white thinset (or you can use gray), a water supply and a large enough bowl to submerge your towel in.
Mix up your thinset by first putting a little water in the bottom of your bowl and then add your thinset powder. The consistency you want is like the consistency of paint – we want it thinner than usual so you can spread it easier and so that the towel soaks it up as well. A little wooden stick is a good mixing tool. Keep adding water and powder until you have the consistency you want.
When your thinset is ready, completely submerge your towel into the thinset. Then lay it out flat on the board and either use your hand or a paint brush to smooth in more thinset in areas that need more thinset. Completely cover in thinset and then flip over and cover the back side as well.
Now the fun part – sculpting. On the front side, using your hands, start pulling in the towel in those areas that you want to create your sculpture with. I cut a plastic cup in half and put it under the towel to add height to the sculpture. You can use whatever objects you want – be creative.
Important note: Keep in mind that you will be cutting and gluing small tesserae in all these nooks and crannies, so don't create something impossible to mosaic on; try to make your creases as vertical as possible and avoid any "under-cuts" where it would be impossible to place your tesserae.
I wanted to show another example of how versatile this technique can be, so I grabbed another towel, mixed up gray thinset, and put a larger plastic bowl underneath. The shapes you can create are limitless.
Now, after you finish the first coat on the front and back, let it dry overnight. This is your foundation and should be thoroughly dry before you resume more coats.
I recommend you do at least 4 coats, letting it dry in between each one – usually 2 hours is a good amount of time between coats. You can do more coats if needed. For the remaining coats, mix your thinset a little thinner. You may even want to pour some on, so that it coats evenly across all the areas. Let thoroughly dry. Coat again.
Immediately after the last coat, and before it is dry, you will want to start smoothing the thinset so you have a nice surface for your tesserae. Use your paintbrush or sometimes fingers work the best for smoothing it all out.
When you have achieved a nice surface and everything is dry, take a medium grit sandpaper and lightly sand where there may still be rough areas. Thinset is dusty when it is dry, so this is probably a job for outside. Remember your dust mask. After you have a smooth surface that you are happy with, you can take a damp cloth and lightly remove any dust, then you are ready to mosaic. You can use WeldBond or thinset as your adhesive as well as others that are appropriate for your project.