Choosing Laboratory Filter Paper: Qualitative, Quantitative and Hardened Grades

At a glance. Tech Inc. Laboratory Filter Papers come in qualitative, quantitative (ashless) and hardened grades. Pick by particle size to retain, flow rate needed and whether the residue will be ignited.

Three families

• Qualitative: clarifying liquids and collecting precipitates.

• Quantitative (ashless): gravimetric analysis; ash below about 0.01%.

• Hardened: strong when wet, for vacuum and Buchner funnels.

Retention and speed

Fast papers retain coarse particles (about 20 to 25 µm); slow papers retain fine precipitates (about 2 to 3 µm) but filter more slowly.

When to use a membrane filter instead

For defined pore sizes below about 1 µm, sterility or particle counting, use a membrane disc filter.

Frequently asked questions

Can papers be used under vacuum? Use hardened grades, or support the paper.

Send your grades and sizes to mail@techincresearch.com.