Most filter paper is made of cotton fibers. But, generally speaking, filter paper for different purposes will be made in different ways. Because its material is made of fibers, it has many holes in the surface through which liquid particles can pass, whereas larger solid particles cannot. This property allows the separation of liquid and solid mixtures. Filter paper can be divided into qualitative and quantitative. In the application of analytical chemistry, when inorganic compounds are filtered and separated from sediments, the residues collected on filter paper can be used to calculate the loss rate in the experimental process. Qualitative filter paper has more cotton fibers after filtration, so it is only suitable for qualitative analysis. Quantitative filter paper, especially ashless filter paper, can resist chemical reaction more effectively through special processing procedures, so the impurities generated are less and can be used for quantitative analysis. In addition to the filter paper used in general laboratory, there are many applications of filter paper in daily life and engineering. Coffee filter paper is one of the widely used filter paper. The filter paper on the outer layer of tea bag provides high softness and wet strength.