Part 3 of this series describes various filter paper cone folding techniques. Read on to see the options for getting a good seal over your conical funnel.
| Folding method | Comments | |
| Quadrant folded | Fold the paper into exact quadrants. (Diag 1) |
Standard, very common technique |
| Quadrant folded | Fold the paper into quadrants, then open to form a semicircle, identifying the center line.
Next, make two further folds, either in the same or opposite direction. The result is a 60° cone when the paper is opened out. |
Allows the paper to filter in a more balanced manner than standard quadrant technique
Has certain disadvantages, especially if the precipitate tends to creep |
| Quadrant folded | Fold the paper into quadrants. Make an extra fold at a slight angle from the center. The result is an angle at the apex of the cone slightly more than 60°.  (Diag 3) |
Can provide a better fit when wet and loaded with precipitate |
| Quadrant folded | Fold the paper into quadrants, Tear off the corner of the outer fold  (Diag 4) |
Enables the rim of the filter paper cone to seal better against the glass funnel than a standard quadrant fold
Tearing the corner is better than cutting as it tends to stagger the two thicknesses of paper. |
| Pleated/Fluted paper | Pleating
Fold the paper into exact quadrants. Make a further two folds bringing the outer edges in two the center line. Open the folded circle and invert. Push alternate folds into the center, making a neatly pleated arrangement.
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Pleating filter papers is a very widely performed technique and offers improved flow characteristics compared to c |
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