About the General Classification of Filter Papers

General classifications

As we know, the filter paper is a commonly used tools in experiment and in many industries. There are many kinds of filter paper, laboratory filter paper, industrial filter paper, edible filter paper, filter screen, etc. They have their own uses, here we can summarize a good common method for selecting filter paper:
1. Please bear three “High” in mind: high binder content, high tensile strength and high filtration efficiency. For the filter material, small background dust accumulation is suggested.
2. Fiber diameter: The smaller the fiber diameter, the better the interception effect and the correspondingly higher filtration efficiency
3. Effective area: The effective area is large, that is, the filter paper uses a large area, the dust holding capacity is large, the resistance is small. Even though with higher cost, the service life will be greatly increased.
4. Hardness: Filter paper becomes wet during filtration, and some experimental procedures for long-term filtration should consider the use of tougher filter paper after wet water.

Laboratory filter paper classifications

For the laboratory filter paper, it can generally be divided into two types: qualitative and quantitative. After filtration, there are more cotton fibers for the qualitative filter paper and for quantitative filter paper, it can better resist chemical reactions after special treatment procedures more effectively, so the generated Fewer impurities and can be used for quantitative analysis.

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key factors

On the market, there are many filter papers available. How to get the most suitable ones for your experiement? HAWACH has summarized key factors based on years’ experience and professional industrial knowledge. Filter papers are classified into different types based on various criteria, including their applications, porosity, retention characteristics, and material composition. Here’s a general classification of filter papers:

1. Qualitative Filter Papers:

Purpose: Used for qualitative analysis and general filtration tasks.
Characteristics: These papers are often fast-flowing and have larger pores, making them suitable for capturing larger particles and precipitates.
Applications: Qualitative filter papers are commonly used in tasks like gravimetric analysis and general particle filtration.

2. Quantitative Filter Papers:

Purpose: Used for quantitative analysis, gravimetric analysis, and precise measurements.
Characteristics: These papers have a defined retention rate and are designed to retain particles within a specified size range.
Applications: Quantitative filter papers are used when precise measurements of mass or substances are required.

3. Ashless Filter Papers:

Purpose: Used for applications where minimal ash content is critical, such as gravimetric analysis.
Characteristics: Ashless papers are specially treated to reduce ash content, ensuring accurate measurements of the residue left after filtration.
Applications: Ideal for applications where the ash content might interfere with analytical results. Some filter papers are made by special production steps, such as in testing medicine to measure nitrogen content in blood, nitrogen-free filter paper must be used. Please note the zinc chloride is unsuitable to use filter paper for filtration, as it will bring damage to the filter paper.

4. Glass Fiber Filter Papers:

Purpose: Designed for high-temperature and harsh chemical filtration.
Characteristics: These papers are made from glass fibers and are resistant to most acids, alkalis, and organic solvents. They are also heat-resistant.
Applications: Used in air and water quality monitoring, stack emissions testing, and high-temperature filtration.

5. Qualitative Filter Papers with Binder:

Purpose: Used when extra strength and integrity are needed.
Characteristics: These papers have a binder material (usually a resin) added to increase their wet strength and reduce tearing.
Applications: Commonly used in applications where filter papers may be subjected to mechanical stress, such as vacuum filtration.

6. Chromatography Filter Papers:

Purpose: Designed for use in chromatography applications.
Characteristics: These papers have specific pore sizes and thicknesses to facilitate the separation of substances in chromatography techniques.
Applications: Used in techniques like paper chromatography and thin-layer chromatography.

7. Filter Paper Circles and Sheets:

Purpose: Offered in various formats for different filtration setups.
Characteristics: Available as pre-cut circles or sheets in different sizes, making them suitable for various filtration apparatus.
Applications: Versatile and used in a wide range of filtration tasks, including gravity filtration and Buchner funnel filtration.

8. Membrane Filter Papers:

Purpose: Designed for precise filtration tasks.
Characteristics: These papers are often made from membranes with specific pore sizes for precise particle retention.
Applications: Used in microbiology, water analysis, and analytical chemistry for critical filtration tasks.

9. Specialty Filter Papers:

Purpose: Tailored for specific applications.
Characteristics: Specialty filter papers are designed to meet unique requirements, such as chemical resistance, high-temperature resistance, or specific pore size specifications.Applications: Varied, depending on the specialty paper’s design and characteristics.
The classification of filter papers helps users select the most suitable type for their specific filtration needs, ensuring efficient and reliable results in a wide range of laboratory and industrial applications.