why stone cause rust and stains of yellow

why stone cause  rust and  stains of yellow

There are two reasons: 
A high iron content of hematite stone material itself or ferric sulfate containing iron materials, such as easy to oxidation and corrosion, stone material surface turn yellow.Rust spots.Serious corrosion, even Kong Si crystalline particles exposure or formation.
Is a kind of stone material in sand saw sawing plate when MAO, the abrasive shot is not clean, left behind the plate, meet water oxidation, produce rusty spot.
Another stone without using dry widgets such as stainless steel pieces, may also have rust, pollution plank.So dry stone pendant must adopt stainless steel fittings.Preventive measures:
(1) the board that factory must clean steel shot a thorough clean.Yellow rust to handle clean;
(2) in front of the post to hang for maintenance.In order to prevent the water in contact with the surface of iron;
(3) avoid stone accessories is easy to rust.Such as dry hanging stone accessories, lamps and lanterns, etc.
Countermeasures: the derusting curing agent: first with wet cloth cardiac rusty spot area.Besmear again beat herbicides or other cleaning agent in rusty spot place, if appear rust occurrence fade effect, after waiting for sufficient reaction.Rinse with water.In addition to the board that the rust with a multifunctional protective agent curing.(note: this method is only applicable to granite, not suitable for marble.)