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Sep
Filter Paper Selection Guide: Grades, Pore Sizes, and Best Practices
Filtration is one of the most common techniques in laboratories, from chemistry and microbiology to food testing and water analysis. The right filter paper ensures accurate results by retaining particles of specific sizes while allowing liquids to pass through. With so many grades and pore sizes available, choosing the correct filter paper can be challenging. This guide helps Australian laboratories select the best option for accuracy, efficiency, and compliance.
Why Filter Paper Matters
Different applications require different levels of retention. Using the wrong grade can cause sample loss, clogging, or incomplete filtration. LabChoice Australia supplies high-quality filter papers designed for compatibility with Buchner flasks, funnels, and vacuum filtration setups, meeting international standards for laboratory use.
Filter Paper Grades and Pore Sizes
| Grade / Type | Typical Pore Size (µm) | Best Use Cases |
|---|---|---|
| Coarse (8–25 µm) | Fast flow rate | Sand, large precipitates, soil analysis |
| Medium (5–8 µm) | Balanced retention | General chemistry, school labs |
| Fine (2–5 µm) | Higher retention | Protein precipitates, crystalline compounds |
| Very Fine (<2 µm) | Slow flow, maximum clarity | Bacteria removal, fine particles, QC testing |
| Ashless Papers | Low ash content after ignition | Gravimetric analysis, environmental testing |
Best Practices for Choosing Filter Paper
- Match pore size to sample: Fine papers for proteins or bacteria, coarse for soil or bulk precipitates.
- Consider flow rate: Faster filtration saves time but may reduce precision.
- Use ashless papers for analysis: Ideal for gravimetric methods where minimal residue is required.
- Pair with correct funnel: Use filter paper with compatible LabChoice Buchner or glass funnels for optimal fit.
Case Study: Food Testing in Australia
A Queensland food QC lab adopted LabChoice ashless filter papers for sugar analysis. By using fine-grade ashless filters, they achieved consistent clarity and reduced contamination, ensuring compliance with industry standards.
LabChoice Advantage
LabChoice Australia supplies a wide range of filter paper grades to support everything from classroom demonstrations to advanced analytical chemistry. Each paper is manufactured for consistent pore size and flow rate, ensuring reproducibility and reliability in every experiment.
FAQs
Can I reuse filter paper?
No, filter paper is single-use and should be replaced after each filtration.
What is ashless filter paper?
Filter paper designed to leave minimal ash residue after combustion, ideal for gravimetric analysis.
Which grade is best for schools?
Medium-grade filter papers offer a balance of flow rate and retention for general teaching labs.
Can filter papers be used with vacuum filtration?
Yes, LabChoice filter papers are compatible with Buchner flasks and funnels for vacuum setups.
📚 References
Standards & Specifications
- ISO 3310-1:2016 – Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth (particle retention standards relevant to filter media). International Organization for Standardization. https://www.iso.org/standard/60109.html
- ASTM E832-81(2019) – Standard Specification for Laboratory Filter Papers. ASTM International. https://www.astm.org/e0832-81r19.html
- ASTM D3860-98(2018) – Standard Practice for Determination of Pore Size Characteristics of Membrane Filters Using Automated Liquid Porosimeter. ASTM International. https://www.astm.org/d3860-98r18.html
Academic & Safety Guides
University of Melbourne – School of Chemistry – Undergraduate Laboratory Manual: Filtration Methods and Use of Filter Papers. Melbourne, Australia.
American Chemical Society (ACS) – Filtration Techniques in Educational and Research Laboratories. ACS Education Resources. https://www.acs.org/education
CSIRO – Laboratory Practice Guidance – Use of Filtration and Filter Media in Australian Research Facilities. CSIRO, Australia. https://www.csiro.au
