Lab Technique · Entry 22 of 42
Filtration / Sieving
Mechanically separating particles by size.
How it works in the lab
Labs separate solids from liquids by gravity filtration through fluted filter paper, by vacuum filtration with a Buchner funnel for speed, and by sieving powders through stacked meshes of known pore sizes for particle-size analysis. Choosing among them is a practical decision: vacuum filtration is fast but can pull fine particles through, while careful gravity filtration is slower but cleaner. Because filtration is a physical size cutoff, knowing your particle sizes tells you whether the method can work at all.
Research Findings
One of the most fundamental separation techniques in all of chemistry.
Skills you gain in the lab and kitchen
- Choosing the right mesh or strainer for a job
- Sifting dry ingredients for even mixing
- Straining a liquid for a smooth texture
- Setting up filtration without spills or losses
- Describing separation as a size-based cutoff
How it shows up in baking
Bakers sift flour to break up clumps and aerate it so it mixes evenly, push custard through a fine strainer to catch bits of cooked egg, and dust powdered sugar through a sieve. Straining stock or seeds from a puree is the same mechanical size separation. Both settings pick a mesh fine enough to catch what must go and coarse enough to let what should pass through.
Recipes that demonstrate this technique
Each card shows exactly where the technique appears inside that recipe's method.