Why would you use weighing paper instead of filter paper for weighing an unknown sample?

The weighing paper is specially designed to measure the weight of solid and powdered samples. It has a non-stick property. The sample which is weighed through weighing paper does not stick to the paper. Therefore, the weight of the sample is precisely transferred to another apparatus. In addition to this, moisture does not get absorbed to weighing paper. Therefore, the sample is not able to make contact with water molecules.

In the case of filter paper, the filter paper absorbs moisture easily. Therefore, the sample can be corroded by filter paper. Some particles of the sample may stick to the filter paper. This disturbs the precision of weighing as the mass weighed will not be equal to mass transferred.

Therefore, it is better to use the weighing paper instead of filter paper to weigh an unknown sample.