Buchner vs Hirsch Funnel: Which Vacuum Filter Fits Your Lab?
A Buchner funnel is a flat-bottomed porcelain or plastic filter that sits on a side-arm flask; a Hirsch funnel is a smaller, cone-shaped porcelain cup that plugs into the same flask. Both use vacuum to pull liquid through paper, but their geometry and volume capacity differ.
Students grab the first funnel they see, thinking “small glass = same job,” then watch fine crystals climb up the Buchner walls or clog the tiny Hirsch stem. The mix-up wastes time and product, so labs stock both and label fast.
Key Differences
Buchner: wide disc, 30–200 mL slurry, great for bulky precipitates. Hirsch: narrow cone, 5–30 mL, ideal for milligram-scale recrystallizations. Both need vacuum, but Hirsch’s steeper angle gives faster flow for small samples.
Which One Should You Choose?
Scale decides: running 1–2 g? Hirsch saves solvent and time. Anything larger or chunky—go Buchner. Many labs keep both; Hirsch for discovery chemistry, Buchner for scale-up.
Can I use the same filter paper?
No—Hirsch takes smaller, pre-cut circles or micro-filters; Buchner uses standard 55 mm or larger sheets.
Do both need the same vacuum level?
Yes, but Hirsch clogs faster; gentle vacuum prevents channeling and crystal loss.