Green silicon carbide (GC) is one of the ideal abrasives for polishing marble due to its high hardness and sharpness. The following are the specific steps and precautions for using green silicon carbide to polish marble:
1. Polishing steps
Surface pretreatment
Clean the surface: Remove stains, wax layers or old coatings on the marble surface to ensure that there are no impurities.
Rough grinding and leveling: If the stone has scratches or is uneven, first use a diamond grinding disc (50#-200#) or a coarse-grained green silicon carbide grinding block (such as 60#-120#) to initially level it.
Gradual grinding
Medium grinding (transition stage):
Use green silicon carbide abrasive (180#-400#) with a hand grinder or floor grinder to evenly grind until there are no obvious scratches on the surface.
Note: Each grinding disc must completely cover the grinding marks of the previous one before changing to a finer model.
Fine grinding (refining stage):
Replace with fine-grained green silicon carbide (800#-1500#) to further eliminate tiny scratches and improve glossiness.
Polishing stage
Use green silicon carbide polishing pads (2000#-3000#) or green silicon carbide grinding blocks with resin binders, and use a low-speed polishing machine (recommended speed 1500-3000 rpm) to evenly polish until the surface has a matte effect.
Auxiliary materials: Tin oxide or oxalic acid polishing paste can be used to enhance the effect.
Final treatment
Clean the surface dust and apply stone protective agent (such as fluorine protective agent) to prevent later contamination.
2. Precautions
Abrasive selection
The particle size of green silicon carbide needs to be increased in steps (such as 60#→120#→180#→…→3000#), and no number can be skipped.
For white or light-colored marble, it is recommended to use high-purity green silicon carbide (few impurities) to avoid yellowing caused by iron residue.
Equipment and operation
When hand-polishing a small area, you can use an angle grinder + green silicon carbide grinding disc; for large areas, it is recommended to use a weighted stone grinder.
Keep the equipment stable to avoid local over-polishing and dents.
Spray water to cool down the whole process to reduce dust and prevent stone burns.
Marble characteristics adaptation
Soft marble (such as white marble) needs to reduce pressure to avoid too deep scratches.
If the stone contains impurities (such as pyrite), it may need to be repaired before polishing.
3. Common problems solution
Scratches remain: return the previous abrasive and re-polish to ensure that the rough grinding marks are completely eliminated.
Uneven gloss: Check whether the abrasive is worn or the equipment speed is unstable, and replace the grinding disc if necessary.
Whitening phenomenon: It may be due to water infiltration. After polishing, it needs to be fully dried and then apply protective agent.