Thinset is a cement adhesive you will mix with water until it is thick. Thinset can be sticky and messy, but it's a strong adhesive that helps hold the mosaic project. You can purchase thinset cement at any hardware store. You can work on wood and terracotta pots and glass. Never mix thinset with water. Mix thinset with admixes such as latex or acrylic liquids. This makes the thinset sticky.
Silicone is ideal for mosaic glass surfaces. It is transparent and is available in a caulking tube. However, when using silicone, you want to apply small portions to the mosaic surfaces, as it is difficult to remove -- if it ever spills out between the tiles.
If you are creating mosaic with metal, wood or even glass surfaces, epoxy adhesive works well with these materials. Epoxy can also hold up in various weather conditions. However, this adhesive has a noxious odor and must be used quickly.
Solvent-based glue such as Liquid Nails are used for outdoor mosaic walls. However, the downfall of these glues is that they are water-based and cannot be used for mosaic projects such as for patios or fountains.