Weigh 1g sample with accuracy  to 0.0002 g, put the  sample on the  weighing bottle with constant weight, put the bottle in 120 ℃ + 2 ℃ oven, bake it for four hours. Take the sample out and put it in dryer for cooling it to room temperature, weigh it to constant weight, the calculation is as follows:
                                           m2－m1
       Solids content %=                            ×100%
                                                m
where:
m1 - net weight of weighing bottle, g.
m2 -representing  the weight of the dried sample and the weighing bottle, g.
m - the mass of the sample before drying, g