Mass is the content of material in an object whereas weight is gravity force acting on an object. Although both terms are used as one and same however it is not true. Mass pieces are available in varying accuracy class E1 being at the highest order of accuracy to M3 at the lowest accuracy level.
Above classes are governed by the tolerance limits defined by international legal metrology Guideline OIML R111-1 and 2. This guideline defines the shape, sizes, dimension and finishes of the mass pieces to be qualified as OIML mass pieces.
In order to calibrate a weight / mass it is essential to have a standard or master weight which is having superior accuracy and uncertainty and comparator or scale of appropriate readability and repeatability.
At CALITRON we calibrate weights / mass using valid procedures based on OIML R111-1 from accuracy Class E1 and coarser covering range of 1 mg to 50kg maximum. E1 class weights are calibrated using subdivision and substitution method to achieve desired results keeping measurement uncertainties to the minimum.