There are four factors that should be considered by the experimenters when selected the proper filter papers.
The first factor is the hardness. The filter paper will become wet when it is used in the filtration. And so the experimenters should consider those papers which are tougher after wet by water when they prepared long-term filtration.
The second factor is the efficiency of filtration. The density and the size of the pores will affect the paper’s efficiency of filtration. The filter paper with high efficiency has fast filtering speed and high resolution.
The third factor is the capacity. The pores on the surface of the filter papers will always be blocked by the solid particles when filtering. The more and denser the pores are on the surface of the filter papers, the higher capacity the papers would have and the more filters are allowed to be filtered.
The fourth factor is applicability. There are some filter papers which are made by some specific steps. For example, nitrogen-free filter paper should be applied in the use of the experiments which are in the determination of blood nitrogen content in pharmaceutical products.