Specifications Table

Product Name – Whatman Cellulose Filter Paper Grade 91
Quantity/Pack Size – 11.0cm (Pack of 4000), 12.5cm (Pack of 4000), 15cm (Pack of 1000), 16.5cm (Pack of 1000), 18.5cm (Pack of 1000), 19cm (Pack of 1000), 24cm (Pack of 1000), 58x58cm (Pack of 500), 61x61cm (Pack of 500)
Form – Circular/Square Sheets
Grade – 91 (Medium Retention, 10?m)
Application – General lab filtration, gravimetric analysis, air monitoring

Product Overview

Whatman Grade 91 cellulose filter paper is engineered for superior performance in demanding laboratory applications, combining medium particle retention with exceptional wet strength. With a nominal pore size of 10?m, this grade efficiently captures fine particulates while maintaining fast flow rates, making it ideal for routine filtration tasks. The high-purity cellulose composition ensures compatibility with a wide range of solvents and reagents, including mild acids and alkalis, without compromising structural integrity. Its uniform thickness and smooth surface minimize fiber shedding, reducing contamination risks in sensitive analyses. The filter papers consistent weight and ash content (<0.06%) further enhance reliability in quantitative procedures. Designed for durability, Grade 91 maintains its mechanical strength even when wet, preventing tears during handling or under vacuum pressure. Its versatility extends to both qualitative and semi-quantitative applications, though it is not recommended for critical gravimetric work where ashless grades are required. The papers natural hydrophilicity ensures rapid wetting and even liquid distribution, optimizing filtration efficiency. Available in multiple diameters and square formats, this filter paper adapts to various funnel sizes and filtration setups, from standard lab funnels to specialized apparatus. The bulk packaging options provide cost-effective solutions for high-volume users while maintaining individual sheet protection to prevent damage. Whether used in educational labs, research facilities, or industrial quality control, Whatman Grade 91 delivers consistent, reproducible results with minimal preparation time.

FAQs

1. What is the particle retention capacity of Whatman Grade 91 filter paper?

This filter paper has a medium retention capacity with a nominal pore size of 10 micrometers, suitable for capturing fine particulates while allowing efficient flow rates.

2. Can this filter paper be used with organic solvents?

Yes, Whatman Grade 91 is compatible with a wide range of organic solvents, including alcohols, hydrocarbons, and mild acidic or alkaline solutions, though prolonged exposure to strong acids may affect performance.

3. How does the wet strength of Grade 91 compare to other Whatman grades?

Grade 91 offers superior wet strength compared to standard qualitative grades like Grade 1, making it more resistant to tearing during filtration, though it is not as strong as specialized reinforced grades.

4. What is the typical ash content of this filter paper?

The ash content for Whatman Grade 91 is less than 0.06%, which is relatively low but not classified as ashless, so it is not recommended for applications requiring ultra-low ash residues.

5. Are there any special storage conditions required for maintaining performance?

Store the filter paper in its original packaging in a cool, dry environment away from direct sunlight and chemical vapors to prevent degradation or contamination before use.