Qualitative Filter Papers-Grade 6: 3μm

Whatman gridded filters have clearly defined grid lines spaced at 3.1 or 5 mm intervals.

The special ink used is nontoxic and completely
free from bacterial growth inhibitors.

Whatman black mixed cellulose esters are available plain for automatic colony
counting applications, as well as gridded to assist in manual counting procedures.

Black membranes provide contrast between residue or cell colors and the filter
without having to counter-stain the membrane.

Grade 43: 16 μm*
Intermediate in retention between Grades 40 and 41, and twice as fast as Grade 40.

Typical applications include foodstuffs analysis, soil analysis, particle collection in
air pollution monitoring for subsequent analysis by XRF techniques, and inorganic
analysis in the construction, mining, and steel industries.