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Polyester

• The stone must be completely dry
• If you do not thoroughly mix the resin and hardener it will probably cure anyway
• You can use most colors to tint
• Many varieties available
• Good adhesion when prepared properly
• Can easily be used for patching
• Stone surface must be abraded before sticking
• Should not be used for exterior or in moist locations
• Quick curing time (normally 10 minutes to 1 hour depending on the product and the weather)

Epoxy

• Stone can be a little moist
• Resin and hardener must be thoroughly mixed to cure
• You should use only colors made for epoxy
• Not as many varieties available
• Great adhesions when prepared properly
• Not as easily used for patching
• Stone surface should be abraded, but it will stick to a smooth surface also
• Can be used for exterior and moist locations
• Slow curing time (normally 7 hours, depending on the product and the weather)

Keep in mind that improper mixing of epoxies will result in a weak joint. Notwithstanding the temperamental nature of epoxies, I recommend using it whenever possible. Also, it is often necessary to test an adhesive on light or porous stones before using, just in case it might stain the material.

Penetrants

We often use penetrants on fragile stones, which helps prevent possible breakage when cutting. A penetrant will rarely work if the stone is not prepared properly. Be sure to clean the stone well and allow it to dry thoroughly. Let the adhesive set up for at least the recommended setting time, or longer if possible. Leave the clamps on as long as possible or until completely cured. Some people may classify penetrating as filling. Normally a penetrant adhesive will settle just below the surface of the stone unless an excess amount is left on the face of the stone.

Crystal Clear

You can normally match white marble better if you start with a crystal clear adhesive then add a small amount of color to create translucency (semi-transparent). Many colored marbles and granites have clear crystal sections occurring naturally in them. When used as a filler, crystal clear can imitate those natural sections of the stone.

Consistency/Viscosity

I think it is better to use a flowing adhesive for laminating edges and the knifegrade for filling. Sometimes you may need to mix the two together to get a better consistency to suit your needs. One of the best ways to achieve a tight joint is to use the thinnest adhesive suitable for the job.

Color Matching

If you use a polyester adhesive, you would normally use polyester colors to tint it. Be sure to mix the colors well and verify the match before adding hardener to it. With an epoxy adhesive you can mix the resin and hardener before adding color because of the slow curing time. Once you have added hardener to the mix, your working time is limited, so you must work rapidly. It is recommended that you do all of the necessary fitting before mixing colors or adding hardener. Add only the recommended amount of hardener and mix well.

If you use an epoxy adhesive, you should always use the epoxy colors to tint it. These colors are made especially for epoxy to ensure longevity, i.e., no fading. Most epoxies cure slowly but need to be mixed well. I recommend mixing the resin and the hardener, and adding colors afterwards to guarantee a good mix. Even though you have more time to work, it is still a good idea to prepare the work for sticking or laminating before mixing the adhesive.

To get the best color match you should look closely at the stone and identify all of the colors you see in it. All or most of those colors are present throughout the stone except in different concentrations.

If you are trying to stick two pieces together at a white vein but gray, mauve, and pink are also in the stone, then your color should consist mostly of white. I have heard that if you have more than three colors then you should start over. With experience you will find that sometimes it is necessary to use more than three colors: especially with very colorful stones. After you have sharpened your color detection abilities, color matching will become easier.