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What is Grade 351?

This is an extremely fine retention filter for critical gravimetric analysis of very fine particles, such as barium and lead sulphates, stannic and nickel sulfide for use in glazes, coatings and pigments. It also filters calcium oxolate, calcium fluoride and cuprous oxide. It eliminates large particles that might otherwise interfere with sensitive instrumentations. Likewise it is highly recommended for the analysis of insoluble particles in oils and animal or vegetable fats. A common example is use of Grade 351 as a calcium carbonate filter for analysis in the cement industry. Grade 351 has the smallest pore size of all our Filter Paper grades. The Ash content is 0.007%. The high purity of Grade 351 Filters also makes the suitable for processes that require ashing.

Whatman Cross Reference = No.42
Speed class Very Slow Filtering
Thickness (mm) 0.14
Pore size (μM) 2-3
Weight (g/m²) 84
Filtration Speed (sec*) 180
Burst Strength (Kg/cm²) > 0.20
*According to DIN 53137
Available Sizes
Diameter (mm) Product Code
55 351055
70 351070
90 351090
110 35110
125 351125
150 351150
185 351185
240 351240
300 351300
320 351320