1,Stone rusty spot, it usually is from the reaction of the iron material in stone after oxidation. Iron, water, oxygen is the 3 big factors to cause the rusty spot. Generally, we divide them into 2 kind according to their different reaction level.

(1),Deep level rusty spot.  Many stone exist a portion of iron, when the iron contact fully with water and oxygen, it will cause oxidation and become rusty spot. In addition,  the alkali material in the cement will react with the iron in the stone when meet the water, it will cause rusty spot also.

(2),Surface level rusty spot. When exploit stone, process stone, or during transportation or installation, the stone surface will contact with some iron material and remain little residue of iron. These iron material will react with the water, oxygen in the air and become the rusty spot.

2,The prevention for rusty spot, it is the effectively control for its 3 reaction factors: water, oxygen, iron.

(1),before installation of the stone, must use the good quality stone protection material to process the 6 sides of the stone. Stop the iron in stone to contact the water.

(2),try best to avoid the using of high alkali cement for the installation of the stone.  Reduce the chance of the contact between alkali in cement and iron in stone.

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