INSTRUCTIONS FOR FINISHING A HANDMADE TILE MOSAIC
Step 1: Arranging your handmade tiles
- Arrange the tiles on the mosaic backing board in a pleasing design. Use either 1/4" thick Hardibacker board (from Home Depot, is very heavy, for outside), or WediBoard (for outside, light, easiest to cut, my favorite but expensive). A new product, Easy Board is available at Home Depot but it doesn't have the same rigidity as the other boards. It is inexpensive, cuts easily with a utility knive, and is ok oudoors if the edges are totally sealed. Do not use wood if you want to put your piece outside or if it can possibly get wet (a table), even if you paint or shellac it--it will fall apart eventually when moisture seeps in. In many climates, humidity will make the wood swell and tile will pop off wood backing.
- At this point is when I usually put a hanging wire through the backing board of a hanging mural. On small mosaics, I use a 16ml copper wire and put it through 2 holes I've made in the backing board...leave the ends about 2" long and bend them flat on the side of the board where the tiles will go. These wil be attached with mastic and remain under the tiles and grout and will support your finished piece. (If you're working within a frame, this isn't necessary.) There are also 'wedi hangers' available that I use for large mosaics (purchase at mosaicsmalti.com)--they come in two types -- one for permanently attaching a mural to the wall with anchors, and a 2nd (that I usually use) where you can string a wire on the mosaic and hang it on the wall like any picture.
Step 2: Attaching the tiles with mastic
- After you are sure you are finished arranging your tiles on the backing board, you are ready to attach them permanently with mastic. Use Type 1 Acrylic Mastic (premixed, ready to use), Omni-Grip (premixed, ready to use) or Polyblend Thinset (a dry powder that add water to) -- all are available at Home Depot, Lowe's or a tile store. If I'm using large rocks or heavy glass pieces, I find that Laticrete brand thinset is very strong...it is a powder that needs to be mixed with water.
- To mix thinset: Place the powder into a plastic cup. Add water a teaspoon at a time, stirring as you go. Continue to add small amounts of water until the mixture is the consistency of toothpaste. Add more dry powder if it gets too runny. The mastic will be usable for several hours so if you’re working slowly and if it gets thick, it is ok to add a little more water to soften it.
- Apply the mastic to the back of each tile by lifting it from its position on the backing board. It is not necessary to cover the whole tile back--just put a dab on the tile to tack it down. Press slightly when you reposition the tile on the backing board. Since these tiles are handmade, there may be variations in thickness – build up the mastic a bit more under thinner tiles. If the tiles are not sticking, you probably aren’t putting on enough mastic or you may not have added enough water to the mastic. Once all the tiles are attached to the board, let it dry overnight. Be sure to wipe away any mastic that is on the face of the tiles – it can be gently scraped off or wiped with a damp rag. Be sure the mastic hasn't seeped up between the tiles so that it could show through the grout -- take a toothpick and dig it out if that has happened.
- Discard any remaining mastic in the garbage. Do not rinse it down the drain – it will create a clog!
Step 3: Grouting your project (USE SANDED GROUT) ---this process is called 'dry grouting'
- Check again to be certain that all the tiles are firmly adhered to your backing board. Reattach anything that appears lose and let it dry before proceeding.
- --Create your workspace by covering it with a couple of layers of newspaper – grouting is messy! You’ll also need a clean rag nearby. Now is the time to find a pair of rubber gloves too – grout is very drying to your skin and may adhere to your fingernails.
- --Place your grout into a disposable plastic container (cool whip or cottage cheese containers are easy to work with). Slowly add water, constantly stirring the mixture. Continue to add water until a thick paste forms. Mix thoroughly to dissolve all lumps of dry grout that might be in the bottom of your container. The grout will be gritty (use sanded grout) and about the texture of very thick oatmeal or cookie dough.
- --Dampen and then squeeze ALL of the water out of a small sponge and use this as a scoop to apply grout over your tiles. Keep picking up more grout and smear the whole surface, filling in all the spaces between the tiles with grout. Don’t rinse the sponge – keep adding grout without adding any water. Don't build up a layer of grout on top of the tiles--the point is to fill the spaces between the tiles. You won’t be able to see much of the tiles yet – just keep spreading the grout, pressing it into all the spaces as evenly as you can. Fill any small holes. Keep the surface as smooth as you can and flush with the surface of the tiles.
- Everything should be covered with grout now and you have quite a mess! You probably can’t even see the pretty tiles. Sprinkle a small amount of dry grout over everything (us the same sanded grout that is the same color of grout that you have used before.) Let your picture set like this for 5-10 minutes. Now you can rinse your grouting sponge -- you won't be using it again.
- --Next, take a dry rag, a wadded up piece of newspaper or what I prefer, is a slice from a styrofoam pool noodle that is cut in half. I use the noodle piece to rub in a circlular motion to reveal all the tiles. Once all the tiles have been revealed (sometimes they are a bit deep -- look for places where there is too much space between larger tiles and you'll often find little pieces there.) Go over the whole mosaic until all the tiles are revealed. Next take a soft rag (towel) and rub over the tiles and grout with a kind of buffing motion-- this step is important for smoothing the grout. The rag also works well to reveal the whole tile surface. Look at each of the tiles...are all ends of the petals of flowers showing? do dogs and cats have their ears and tails? etc. If the tiles look 'smeary' with grout, wait another 3-4 minutes and buff the tiles with the rag again. You may need to lightly buff the tiles with the rag 2-3 more times before they are shiny and all the grout traces have been removed. Set aside and let dry overnight. Often, a slight haze forms and you can remove it by buffing with a soft rag again the next day.
--To seal the grout or not is always another question. I don't seal most of my hanging mosaics unless I'm selling them before they are 3 weeks old...that's about how long it takes for the grout to cure. But I always seal table tops and usually use 'Tile Lab Grout Sealer' that comes from Home Depot in a spray bottle. This has to be done when the grout has dried, but not more than 2-3 days after grouting or it doesn't sink into the grout. Once you spray the mosaic, take a lightly damp rag and wipe the sealer off the tiles....you're only sealing the grout. The tiles have been sealed by the glaze that was fired onto them in the kiln. You just want to be sure the sealer is off the tiles so they are bright and colorful. Let the sealer dry at least overnight before hanging your mosaic outdoors.