We all use it at one time or one other. Whether we’re testing soil samples, eradicating dissolved gases from beer, or maybe simply absorbing that espresso spill.
But have you learnt why you’re utilizing that grade of filter paper? Is it simply because your protocol tells you to?
In this back-to-basics weblog, we’ll assessment a number of the hottest fundamental filter paper grades, and choose out a number of key functions.
Qualitative Filter Paper
Qualitative filter papers are what most customers would contemplate normal goal filter papers. There are an enormous vary of functions out and in of the laboratory. Composed of cellulose fiber, these filters are manufactured from high-quality cotton linters handled to maximize alpha cellulose.
Alpha cellulose is the most steady type of cellulose, with the best diploma of polymerization. Cellulose paper constructed from a excessive share of alpha cellulose, comparable to Whatman paper, is an indication of top quality and consistency.
Qualitative filter paper grades are primarily based on numerous properties together with particle retention, thickness, and weight. Unlike quantitative filter papers, of which ash less grades might be burned off for analytical functions, qualitative papers are extra suited to normal goal use.
Various Types of Qualitative Whatman Filter Paper & their Properties
The most typical qualitative paper grades are 1-6, 595, 597, 598, and 602, which have functions throughout a number of industries. Below are summaries of the grade properties and customary makes use of.
For Whatman Blotting Products, you can find some useful information here:
Grade of Paper:
Filter Paper Grade 2
Sizes Available:
Circle: 42.5 mm – 500 mm (accessible prepleated)
Sheets: 460 x 570 mm to 580 x 680 mm
Characteristics:
Particle retention1: 8µm
Nominal thickness: 190 µm
Nominal basis weight: 97 g/m2
Nominal ash content2: 0.06%
Utilization:
Grade 2 is barely extra retentive than Grade 1, with an equal improve in filtration time.
Specific purposes embrace:
Plant progress trials, the place the additional absorbency is utilized to carry soil nutrient
Contaminant monitoring in air and soil
Grade of Paper:
Filter Paper Grade 3
Sizes Available:
Circle: 23 mm – 320 mm (accessible prepleated)
Sheets: 26 x 31 mm to 600 x 600 mm
Characteristics:
Particle retention1: 6µm
Nominal thickness: 390 µm
Nominal basis weight: 185 g/m2
Nominal ash content2: 0.06%
Utilization:
Grade three is double the thickness of Grade 1, so it may possibly maintain extra precipitate with out clogging and has elevated moist power. It is designed to be used in Büchner funnels, and the excessive absorbency makes Grade three effectively suited to pattern transport after assortment.
Grade of Paper:
Filter Paper Grade 4
Sizes Available:
Circle: 27 mm – 400 mm (accessible prepleated)
Sheets: 38 x 114 mm to 580 x 580 mm
Characteristics:
Particle retention1: 25µm
Nominal thickness: 210 µm
Nominal basis weight: 92 g/m2
Nominal ash content2: 0.06%
Utilization:
Grade four is a quick filter materials that’s effectively fitted to retention of coarse particles and gelatinous precipitates, comparable to ferric hydroxide and aluminum hydroxide. Specific functions embody:
Air pollution monitoring the place the gathering of superb particles shouldn’t be important
Routine clean-up of organic fluids or natural extracts
Grade of Paper:
Filter Paper Grade 5
Sizes Available:
Circle: 25 mm – 320 mm (accessible prepleated)
Characteristics:
Particle retention1: 2.5µm
Nominal thickness: 200 µm
Nominal basis weight: 100 g/m2
Nominal ash content2: 0.06%
Utilization:
Grade 5 gives the utmost diploma of super particle retention inside the qualitative paper range, with an equal gradual circulation cost. Specific functions embody:
Retaining tremendous precipitates in chemical evaluation
Checking cloudy suspensions in the soil and water analysis
Grade of Paper:
Filter Paper Grade 6
Sizes Available:
Circle: 42.5 mm – 240 mm (accessible prepleated)
Characteristics:
Particle retention1: 3µm
Nominal thickness: 180 µm
Nominal basis weight: 100 g/m2
Nominal ash content2: 0.06%
Utilization:
Thick with a extreme loading functionality, Grade 6 provides comparable particle retention to Grade 5 with twice the flow into charge. It has excessive absorbency and elevated moist energy, and is usually specified for boiler water evaluation.
Contaminant monitoring in air and soil
Grade of Paper:
Filter Paper Grade 591
Sizes Available:
Sheet: 580 x 580mm
Characteristics:
Particle retention1: 12µm
Typical thickness: 180 µm
Basis weight: 161 g/m2
Nominal ash content2: 0.06%
Utilization:
A thick filter paper with very excessive loading capability for quick filtration of medium to coarse precipitates. Offers excessive absorbency and elevated moist power.

Surely, this abstract of properties and functions of those standard qualitative filter papers clarifies why you is likely to be utilizing a number of of those paper grades in your work. For extra info on the broader vary of filter paper grades, obtain our Filter Paper and Membranes guide.

There are many grades of paper, every with its personal distinctive properties and functions.
If you’re not sure whether or not you’re utilizing the proper paper to your software, make the most of our Filter Paper Properties Chart or examine our Whatman filter selector to search out your filter quick.

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