What is Granite?

 

Granite is an intrusive igneous rock (formed from the slow cooling of magma underground), the major component of the continental crust, coarse grained, and composed of quartz along with a variety of feldspar minerals and micas.

How to repair granite chips: You can repair granite chips almost seamlessly with Mister Glue. The nature of this glue makes it so the tighter the fit of the two pieces the better the bond. Mister Glue is an industrial cyanoacrylate which is the same base as superglue or Krazy Glue. It has been distilled numerous times so that the solvents have been removed resulting in a product that is many times stronger than supe glue.

If a corner has broken off a granite countertop clean both surfaces of dust and dirt. Try not to scrape or sand as this will change the shape making for an imperfect fit. Mister Glue will not fill gaps and as said earlier the closer the fit the better. It is a good idea to practice a little putting the pieces together because you do not have much time to move them around once they touch.

Once you know that the fit is exact, place a small bit of glue on one surface of the broken granite. Make sure that is enough that it will cover the whole surface - spreading when the two pieces are pressed together. Hold the two sections of granite tightly together for a few seconds - a bit longer if the section is larger. Some of the glue may squeeze out of the joint - leave that to dry up a bit then take an Exacto Knife and gently scrape off the excess. If you wipe it the glue will spread and possibly stain the stone.

Full cure time is several hours but it takes only seconds for a tight, secure bond to occur. Most of the time you will not be able to remove the piece within a few seconds. 

If the granite is very porous you can use a bit more glue or an accelerator. Sometimes water will work as an accelerator - it primes the surface so that the glue will not soak in. If you use water to prime the surface, let it 'dry' before applying the glue. You definitely do not want a wet surface.

For a small granite chip on the edge of the seam that is still left after you have glued the two pieces, you can take a bit of dust from the granite - grind it and place it in the crack and put a few drops of glue over it. Let it set then you can scrape or sand it smooth. It will be the same color but the finish will obviously be different.

What is marble?
Marble is metamorphosed limestone, composed of fairly pure calcite (a crystalline form of calcium carbonate, CaCO3). It is extensively used for sculpture, as an building material, and in many other applications. Pressure and heat create marble from limestone or dolostone. The various colors result from various minerals present.
Faux Marble is composed of marble dust and often synthetic resin.

How to fix marble?

A corner broken off and marble countertop or fireplace hearth can be difficult to repair without leaving an ugly seam. Mister Glue needs a very tight fit - the closer the two pieces the better the bond - so it generally leaves much more than a hairline crack. This does depend on how the break happened and if the edges are still intact.
Take a light brush or cloth and remove any and all dust from the two surfaces that you are going to glue together. Apply the glue to only one surface. Make sure that you minimally run a bead around the edges so that it is sealed. Criss-cross it a couple of times so that when you squeeze the pieces together that most of the surface is covered. But do not use too much as was said before you want a tight a fit as possible. Gently squeeze the two pieces together allowing any excess to come out the edges. Hold tightly together for a few seconds. Thirty seconds should be plently if it is a small piece. If it is a larger one then you may want to hold it longer. Mister Glue has a very secure bond within seconds but full cure time is several hours. If it is a much larger piece you may want to support it somehow. I have only tested this on smaller pieces not on the much larger.
The glue that has squeezed out the edges you can leave until it has dried a bit but not till it is too hard. Take a sharp knife and gently scrape off the excess.
If there are holes left because edges were not perfect these can be filled with some marble 'dust' and glue. Place the dust in the opening/hole and add a few drops of glue. Let this cure fully and sand or scrape. It will not have the same finish but will be sealed and water proof.

When you put the bottle away tap it down a couple of times and squeeze it gently to clear the spout. Store upright in the freezer and it will last your for years. Hundreds of uses.

Other pages/articles that may interest you:
Household items
Care of Mister Glue