About calibration of the granite surface plate, this depends on use process, if possible, we recommend cleaning the plate at the beginning or the ending of the work. If the plate becomes soiled, particularly with oily or sticky fluids, it should be cleaned immediately.
Clean the plate regularly with specialized cleaning fluid and cleaning method. If we use volatile solvent, the evaporation will chill the surface, in this case, it is necessary to allow the plate to normalize before using it or measurement errors will occur. About the clean time, an hour should be sufficient for smaller plates, two hours may be needed for larger plates.