Filter Paper

Wet-strengthened filter papers are manufactured from a majority of alpha-cellulose. The smooth surface allows for fibre free filtration. They feature a high wet strength and can also be used in the filtration of strong alkaline or acid solutions. Due to their high mechanical strength, they are suited to applications where the residue is removed from the filter, for example with a spatula or a jet of water.

What is Grade 304? This grade covers a wide range of laboratory applications and is used for clarifying liquids and for the rapid filtration of coarser precipitates such as lead sulfate, lead chromate, calcium oxalate, calcium carbonate, aluminum phosphate, barium carbonate and beryllium hydroxide.

Grade 304 can be found in soil analysis, seed testing and in air pollution to collect dust-laden air and is also commonly used in the food industry to separate foodstuffs from associated extracting liquid.

Specification:

• Sizes Whatman Cross Reference = No.1
• Speed class Medium
• Filtering Thickness (mm) 0.16
• Pore size (μM) 5-13
• Weight (g/m²) 73
• Filtration Speed (sec*) 88
• Burst Strength (Kg/cm²) 1.95

• Sizes Whatman Cross Reference = No.113
• Speed class Fast, creped
• Thickness (mm) 0.45
• Pore size (μM) 45-65
• Weight (g/m²) 140
• Filtration Speed (sec*) 14
• Burst Strength (Kg/cm²) 1.8

• Sizes Whatman Cross Reference = No.91
• Speed class Fast
• Filtration Thickness (mm) 0.14
• Pore size (μM) 20-30
• Weight (g/m²) 64
• Filtration Speed (sec*) 30
• Burst Strength (Kg/cm²) 1.6

This fast filtering grade, with extremely high loading capacity is recommended for the filtration of coarse and gelatinous precipitates. The creped surface of Grade 325 also offers higher surface area to increase filtration speed.

Specifications:

• Sizes: 55 to 320 mm
• Whatman Cross Reference = No.114
• Speed class: Very Fast
• Filtration Thickness (mm) 0.17
• Pore size (μM) 17-30
• Weight (g/m²) 73
• Filtration Speed (sec*) 22
• Burst Strength (Kg/cm²) 1.25

• Sizes Whatman Cross Reference = No.41
• Speed class Fast
• Filtering Thickness (mm) 0.17
• Pore size (μM) 8-12
• Weight (g/m²) 84
• Filtration Speed (sec*) 20
• Burst Strength (Kg/cm²) > 0.20

Grade 352 high purity filters from Johnson Test Papers are general-purpose papers for quantitative analysis. This grade has medium flow rate and good particle retention and is the most commonly used acid-washed filter. High-purity filters support accurate analysis in applications sensitive to very low levels of background contamination and in gravimetric analysis where ash content might affect weight measurements of combusted samples.

Specifications:

• Sizes: 55 to 320 mm
• Whatman Cross Reference = No.40
• Speed class: Medium
• Filtering Thickness (mm) 0.15
• Pore size (μM) 3-5
• Weight (g/m²) 84
• Filtration Speed (sec*) 100
• Burst Strength (Kg/cm²) > 0.20

Qualitative analysis

• Low ash content 0.07% (Acid wash treated)
• High wet strength
• Consistent performance Hardened grades available
• Custom cut
• Bulk packaging
• Made of 100% cotton linters
• Supplied in rolls, sheers, discs and folded filters

• Sizes Whatman Cross Reference = No.3
• Speed class Medium Filtering
• Thickness (mm) 0.3
• Pore size (μM) 12-16
• Weight (g/m²) 150
• Filtration Speed (sec*) 65
• Burst Strength (Kg/cm²) 3.90

• Sizes Whatman Cross Reference = No.54
• Speed class Fast
• Thickness (mm) 0.18
• Pore size (μM) 12-15
• Weight (g/m²) 84
• Filtration Speed (sec*) 10
• Burst Strength (Kg/cm²) >0.3

• Sizes Whatman Cross Reference = No.52
• Speed class Medium
• Thickness (mm) 0.15
• Pore size (μM) 5-8
• Weight (g/m²) 84
• Filtration Speed (sec*) 50
• Burst Strength (Kg/cm²) >0.3

• Sizes Whatman Cross Reference = No.50
• Speed class Slow
• Thickness (mm) 0.14
• Pore size (μM) 2-3
• Weight (g/m²) 84
• Filtration Speed (sec*) 180
• Burst Strength (Kg/cm²) >0.3

• Sizes Whatman Cross Reference = No.43
• Speed class Medium fast
• Filtering Thickness (mm) 0.16
• Pore size (μM) 5-8
• Weight (g/m²) 84
• Filtration Speed (sec*) 50
• Burst Strength (Kg/cm²) < 0.20