How to Fold the Filter Paper in the Right Way?

HAWACH filter paper consists of high-purity of cellulose and can cope with the daily filtration steps in the laboratory. It has a great wet break strength, which makes it ideal for vacuum filtration, Brinell funnels, etc. It’s also widely applied to daily clarification and filtration in the laboratory, soil analysis, food analysis, air pollution analysis, etc.

Filter papers can generally be classified as qualitative or quantitative ones. In analytical chemistry applications, when inorganic compounds are filtered to separate out the precipitates, the residue collected on the filter paper can be used to calculate the loss rate during the experiment. Qualitative filter papers are only suitable for qualitative analysis as they produce more cotton fibers after filtration, while quantitative filter papers, especially ash-free grades, are specially treated to resist chemical reactions more effectively and therefore produce fewer impurities and can be used for quantitative analysis.

According to the size of the pores, quantitative filter papers can be divided into 3 types: fast, medium, and slow. Fast filter papers have large pores and slow filter papers have small pores.

1. Fast filter paper: because of the loose quality of the paper, the spots are easy to spread, suitable for samples with large Rf value and viscosity of the unfolding agent.
2. Slow filter paper: for the slow filter paper where the spots do not spread easily, suitable for samples with smaller Rf values and less viscous spreading agents, but with longer spreading times.
3. Medium-speed filter paper is in between.

The correct way to fold filter paper

1. Fold the filter paper in half, twice in a row, into the shape of a 90-rounded corner.
2. Fold the folded filter paper, three layers on one side and one layer on the other, into a funnel.
3. Place the funnel-shaped filter paper into the funnel, with the edge of the filter paper below the edge of the funnel. Pour some water into the mouth of the funnel so that the soaked filter paper is attached to the inside of the funnel, then pour out the remaining water and set aside.
4. Place the funnel filled with filter paper on a filtering funnel stand (e.g. a circle with an iron frame) and place the beaker or test tube holding the filtrate under the neck of the funnel so that the neck end of the funnel rests on the wall of the liquid container.
5. When filling the funnel with the liquid to be filtered, hold the liquid beaker in your right hand and the glass rod in your left hand. When the filtered liquid flows out along the mouth of the cup and then along the inclined direction of the glass rod, the liquid level flowing into the funnel is lower than the filter paper height in the funnel.
6. When the liquid through the physical and chemical experiments filter paper, flows down the funnel neck, check whether the liquid flows down the wall of the cup, injected into the bottom of the cup. Otherwise, the beaker should be moved or the funnel turned so that the funnel end is attached to the wall of the beaker.

Soxhlet extractor filter paper folding method

Roll the filter paper into a cylindrical shape whose diameter is slightly smaller than the inner diameter of the extraction cylinder, tie it with thread at one end, or fill the filter paper cylinder with finely ground extracted solids, gently compact it, cover it with filter paper and then it can be put into the extraction cylinder.