During the experiment, filter paper is usually employed with other filters like the Brinell Filter. The filter paper should be folded into a suitable shape first, and a common folding method is shaping the filter paper into a flower-like one. The higher degree the folding filter paper possesses, the larger surface area it can provide，and the better the filtering effect would be. Attention：Excessive folding will crack the filter paper, so a drainage glass rod needs putting on the multi-layer filter paper with well-proportioned force to avoid the breakage of the filter paper.
Fold the filter paper into a circular corner of a 90-degree angle.
Unclose the folded filter paper to a funnel shape.
Place the shaped filter paper in the filter, and pour some purified water from the mouth with the wet filter paper close to the inner wall. Then pour out the remaining water for later use.
Place the funnel on the rack.
Fill the funnel with sample liquid.
Check that the liquid is poured along the wall to the bottom.