Which adhesive do I use?
Test First - Unless you have used the adhesive on the same surface before, you can always use this simple test to determine if you are using the right one. Glue your tesserae on and wait 24 - 48 hrs. Then try to pry it off. If it is for a wet application such as outside or in a shower, soak in water overnight , then try to pry off again. If the tesserae does not come off , the adhesive you chose is a winner! Always read the label first. Not only does it usually contain some very helpful information, it usually provides a toll-free number should you have any questions about its use or safety. Always check the chemicals you are working with, especially if you are pregnant or have any respiratory ailment. In those cases, a special mask may be called for. Talk to your doctor. Tile Mastic Use over wood, tile (yes, you can tile over tile), Formica, ceramic. Will not stick to metal or concrete. Not waterproof. Mortar based Thin-set - Thin-set is a mortar based adhesive you can mix with water OR an acrylic additive. Best choice for concrete (stepping stones, birdbaths), terra cotta, and backer boards. Will not stick to metal or other non-porous surfaces without special preparation. It is the only adhesive you can use to really 'float' tiles. This means you can build up the adhesive under a thinner piece of tile so that it is flush with the tile next to it. Totally waterproof. Dries white or gray (know which color you are buying before purchase). Do not empty into sink or drain. Seriously! You will regret it when you have to replace your pipes. Read the bag! Everything I know about thin-set came from the back of the bag. Mix with an acrylic additive instead of water to increase its strength and flexibility, and speed drying time. I prefer using the additive. WeldBond Similar to PVA glues (below) only stronger. Waterproof per the manufacturer's literature. Dries clear. Sticks to anything (score smooth surfaces). WeldBond can be purchased on this site on our Tools page. For more info about WeldBond, visit the manufacturer's website at Frank T. Ross & Sons and click on the WeldBond button at the top left of the screen. Cleans up with water when still white.
"Weldbond will work vertically if you do a little trick I found. I know you have that lovely blue painter's tape. Put it over the tesserae you want to glue to something vertical and it will hold them in place until the Weldbond sets up. Then just rip it off. It works really well on bowling balls and vertical surfaces that can't be made horizontal. Plus, I've found that if the tesserae comes off with the tape, it means it would have come off during grouting - so I know where to add that little bit of extra glue!" From techsupport!
PVA Glues (white glue like Elmer's and other craft glues) Sticks very well to wood that is unfinished Must prep painted or stained surfaces (see Surfaces). Can be used with ceramic, porcelain and glass tiles. At least...