Introduction of Filter Paper


Filter paper is a kind of filter tool commonly used in chemical laboratories, usually round in shape, which is made of cotton fiber that has numerous holes for liquid particles to pass through. This property can separate the liquid from the solid.

Proe sizeDifferent form membrane filter, filter paper does not have accurate pore size but a probable number.
Flow velocityThe velocity is mainly affected by pore size and they are proportional to each other. So far there has been high, medium, and low speed.
Ash contentThe ash content derives from the remains that were left by the filtration medium after the air combustion at 900°C
Wet mullenWet mullen is the maximum vertical pressure that paper or cardboard bears per unit area.
CompositionFilter paper is primarily composed of cellulose fibers obtained from wood pulp. The cellulose provides the paper with the necessary porosity and absorbency for effective filtration.
PorosityThe paper is manufactured to have controlled porosity, allowing liquids to pass through while retaining solid particles. The degree of porosity varies among different grades of filter paper.
Particle RetentionThe choice of filter paper grade determines the range of particle sizes it can effectively retain. Filter papers are available in different pore sizes to accommodate various filtration needs.
ThicknessFilter paper comes in different thicknesses, allowing users to select the appropriate grade based on the volume of liquid to be filtered and the desired flow rate.
Grade ClassificationFilter paper is categorized into various grades, each identified by a specific number. Grades such as qualitative filter paper (used for general-purpose filtration) and quantitative filter paper (used for precise measurements) serve different purposes.
ApplicationsFilter paper finds applications in numerous laboratory procedures, including gravity filtration, vacuum filtration, and Büchner funnel filtration. It is used for clarifying liquids, separating precipitates, and isolating solids from solutions.
Qualitative vs. QuantitativeQualitative filter paper is commonly used for general-purpose filtration where precise measurements are not critical. Quantitative filter paper, on the other hand, is employed when precise measurements of the filtered material are required.
Ash ContentQuantitative filter paper is often characterized by low ash content, making it suitable for analytical methods that involve determining the residue left after ignition.
Wetting TimeThe wetting time of filter paper is an important consideration, especially in quick filtration processes. Some filter papers are treated to reduce wetting time.

Filter paper classification

There are two types of filter paper, Quantitative and qualitative :

In general, filter paper can be divided into two types, one is qualitative and the other is quantitative. Qualitative filter paper generally refers to the formation of cotton fibers on the surface after filtration, which is generally only suitable for qualitative analysis and possesses a standard grade and a wet strengthened grade.

Quantitative filter paper

The quantitative filter paper is mainly used for ashing weighing analysis after filtration, that is, gravimetric analysis test and corresponding analysis test in quantitative chemical analysis. The weight of ash after each filter paper is a fixed value, with low ashless < 0.007 %, to express this in a specific way, there is ashless, Hardened low ash, and hardened ashless grades.

The quantitative filter paper is generally for ashless filter paper and must be subjected to special treatment procedures during use. To a certain extent, it can effectively resist certain chemical reactions, so impurities formed on its surface. There will be a lot less, and in general, it is generally used in quantitative analysis.

Qualitative filter paper

Qualitative filter paper is used in general Filtration, qualitative chemical analysis, and corresponding filtration separation, with Low ashless < 0.1%.

The role of filter paper

Because the cotton fiber in the filter paper has a good affinity with water, it can absorb about 22% of water, and the water combined with cellulose in the form of hydrogen bonds is 6% to 7%. In general, it is very difficult to remove. Compared with the affinity for water, the cotton fiber in the filter paper has a weaker affinity with the organic solvent, so in most cases, the paper chromatography method is in the filter paper fiber. Combined with water as the stationary phase, the mobile phase is dominated by organic solvents. When the mobile phase of the organic solvent passes through the sample, the water and the organic phase are continuously distributed, and as the mobile phase moves, the components of the various components are continuously redistributed, further separating the material and purification. This use of filter paper is generally common in chemical laboratories.

In addition to the application of filter paper in chemical experiments, there are also applications of filter paper in our lives. For example, coffee filter paper is one of the widely used ones, this filter paper has high softness. While industrial filter paper is generally used to adsorb suspended particles in the air.

Hawach Scientific Filter Paper

Filter paper is a kind of paper with good filtering performance. It is loose and has strong absorbance to liquid, Hawach Scientific filter paper is made in a clean room, manufactured from high-purity alpha-cellulose and cotton liner, and special design equivalent to Whatman, Pall, Milipall, Advantech, and so on, besides, it gets CE and ISO 9001 Certificates as well.

Hawach Scientific filter paper offers a wide choice of retention and flow rate combinations for numerous laboratory applications.

classification of filter paper

1. Qualitative filter paper

Qualitative filter paper is widely used in routine laboratory applications, including liquid clarification. The speed of filtration and particle retention depends on the particular grade of qualitative filter paper, we have a slow grade, Medium grade, and fast grade, and you can choose the most suitable type for your applications. Such as Qualitative Filter Paper Disc Grade: BIO-1, Qualitative Laboratory Filtration Filter Paper Grade: BIO-2, Qualitative 20 Micron Filter Paper Grade: BIO-4, Qualitative Chromatography Filter Paper Grade: BIO-5, Qualitative Filter Paper Biology Grade: BIO-6.
For customized sizes, we have 30 mm-650 mm, smaller or bigger sizes are available.

2. Quantitative filter paper

Quantitative filter paper has a smooth surface, extremely low ash content, high capacity, good filtration performance, and excellent retention of particles. We have a slow grade, Medium grade, and fast grade, you can choose the most suitable type for your applications. such as Quantitative Medium Flow Filter Paper Grade: BIO-40, Quantitative Ashless Filter Paper Grade: BIO-41, Quantitative Laboratory Filter Paper Grade: BIO-42, Quantitative Cellulose Filter Paper Grade: BIO-44, Wet Strengthened 10 Micron Filter Paper Grade: BIO-91, Wet Strengthened Chemistry Filter Paper Grade: BIO-113.
For customized sizes, we have 30 mm-300 mm, smaller sizes, and other sizes less than 300mm we can provide.

Type: Disc filter paper, roll, Square type

Filtration Speed (Pore Size): Fast: 20-25μm; Medium: 8-10um; Slow: 2.5-3μm

Regular Diameter: 70mm, 90mm, 110mm, 125mm, 150mm, 180mm, and so on.

We also accept customized sizes such as 240mm, 300mm, 320mm, 400mm, 600mm, and 750mm, OEM Service also is available.

Any questions or help with filter paper, please don’t hesitate to contact us! Email: