The filter paper is one of the common laboratory consumables in the labs. It is normally round in shape. It is often made from cotton fiber and used to filter components. The functional principle of the filter paper is separating the substances through them. The filter papers are normally made from fiber, which is the reason that there are keyholes on it. The keyholes resist the big solid particles and provide pathways for the liquid particles.
The different kinds of filter papers having different characters are made by different technics. So, what are the main factors in the filter papers selection? There exists four: hardness, filtration efficiency, capacity and applicability.
Generally, the filter paper can be divided into the qualitative filter paper and quantitative filter paper. The qualitative filter paperis often used in qualitative analysis. The reason is that the qualitative filter paper produces more cotton fibers if it is filtered. The quantitative one is dealt with the particular process, which makes the paper not react with the common chemicals, in the production. As a result, it produces less impurities and is used in quantitative analysis.