Hardened Quantitative Ashless Filter Paper, 371 Grade, 55mm - 320mm

Hardened Ashless Filter Papers are chemically strengthened for high wet strength and durability in demanding filtration tasks. With an ash content below 0.01%, these acid-hardened papers are ideal for quantitative gravimetric analysis involving strong acids or alkalis. Their tough, smooth surface prevents fibre shedding and enables easy recovery of precipitates without contamination. Suitable for use in Buchner funnels or pressure filtration setups, these papers are available in slow, medium, and fast grades to suit various particle sizes and flow requirements.

Grade 371: is a slow-filtering, acid-hardened ashless paper designed for the retention of very fine precipitates in chemically aggressive environments. With a nominal pore size of 2–3 µm and a filtration speed of 180 seconds (DIN 53137), it is ideal for critical gravimetric analysis and metal determination. Its dense structure is well suited for difficult samples and fine particle retention, including barium and lead sulfates, stannic, zinc, and nickel sulfides, as well as calcium oxalate and calcium fluoride.

Application: Used for difficult and finely grained filtration, barium sulphate, metastannic acids, cuprous oxide, analysis of acid solutions

Key Features

Extremely Fine Retention: Captures small and difficult precipitates for accurate quantitative results.​

High Chemical Resistance: Acid-hardened to withstand strong acids and alkalis during filtration.​

Slow Filtration Speed: Dense filter structure provides high retention even in aggressive matrices.​

Low Ash Content: ≤0.06%, supporting reliable results in ashing and combustion-based analysis.​

Wet Strength: Suitable for spatula or water jet residue removal in Buchner and pressure setups.

• Gravimetric filtration of barium and lead sulfates and dioxides
• Retention of calcium oxalate and calcium fluoride in quantitative testing
• Separation of stannic, zinc, and nickel sulfides
• Metal determination in analytical chemistry workflows
• Filtration of acidic or alkaline solutions in research and industry
• Applications requiring residue recovery without fibre contamination

Available Grades

HS Code / Commodity Code: 4823209000