There are three categories of adhesives used in the natural stone industry: polyester, acrylic, and epoxy. Each is manufactured for a specific purpose, and this will explain which is best for different applications.

The polyester based adhesives are the most commonly used and are essentially a marble adhesive. Because of the properties of the glue they are only suitable for indoor applications. They have a short pot life and a quick cure rate (dependent upon temperature and humidity), so they are the best choice for seams and repairs. They are not meant to be used as laminating glue for granite, although in recent years there have been improvements to certain polyester adhesives which makes them suitable for this application. Be sure to get your color match correct before you add the hardener to the glue, and do not use too much of the hardener (2 to 3% ) or you can affect the integrity and the curing of the adhesive.

Acrylic based adhesives use the same hardener paste as the polyester glues and offer fast cure times, but they offer greater bonding strengths. Like polyester glues they are only suitable for indoor use (temperature fluctuations cause expansion and contraction that can over time cause polyester and acrylic glues to fail ), but they can be used for laminating granite. Acrylic super penetrating is a liquid glue used for filling hairline cracks and fractures - it will fill even the smallest of voids - giving the user the opportunity to repair what might not otherwise be possible. 

Epoxies are the strongest of the adhesives and cover the widest range of applications. They can be used for bonding any stone and are required for all exterior applications. Epoxy adhesives are generally mixed at ratios of 1:1 and 2:1; they have UV filters that inhibit the yellowing of the glue over time; they have a very low shrinkage factor vs. the other adhesives; and they have a longer pot life and cure rate, giving the user the opportunity to mix larger quantities if necessary. Certain epoxies can also be used to bond natural stone to a variety of other materials, including wood, metal, glass, and certain plastics. Epoxies will also bond with the stone when it is damp. It is very important to mix epoxies precisely - it is done by weight and not by volume - as improper mixing ratios will affect the curing of the adhesive.