What is a Lab Filter Paper?

Laboratory filter paper is used for quantitative and qualitative analysis. These papers are made from high quality refined pulp and high purity cotton linters. A wide range of fields including chemistry and biology have applications for laboratory filter paper. Regardless of the application, you need to learn the correct way to use filter paper. As you must know that folding is necessary prior to using filter paper. If you are clueless about how to fold a filter paper and use it for your analysis, keep on reading. In this blog, you get to learn about the stepwise procedure to use a filter paper.

How do filter papers work?

As the name suggests, filter paper is probably used for filtration purposes, but have you ever thought about how it really works?

The semi-permeable paper is used to create a barrier. These papers have different retention capabilities and create a deposited layer on top of the filter paper to create an effective barrier. For effective filtration, one needs to understand the different types and choose a suitable option.  Filter papers are used for different industrial and technical applications. In our daily lives, the most common examples of filtration are coffee filters, tea bags, automotive filtration and sand filters. 

What are the different types of filter paper?

Filter paper is widely demanded for laboratory and industrial applications. These are basically divided into two categories, i.e. qualitative filter papers and quantitative filter papers.

Qualitative filter papers: These papers contain ash and are mostly suitable for filtration of materials which do not require burning.  

Quantitative filter papers: On the other hand, quantitative filter papers are called ashless papers and are mainly treated with hydrochloric acid and hydrofluoric acid.

Depending on the speed of filtration, these papers can also be categorized as fast, medium and slow speed filter papers.

How to use filter paper in a laboratory?

To ensure optimal performance from the filter papers, you need to learn the art of folding and using them.

• Begin by folding the filter paper in half and then fold it again to create a quarter circle. When you open it, you can see 90 degree angles are formed on the filter paper.
• Fold it again as described, and then fold the quarter circle inward to make a funnel shape. Keep in mind that when you are creating a funnel, there will be three stacked layers on one side and one layer on the other side.
• When pouring a liquid into the funnel with a filter paper in it, make sure to tilt the glass rod slowly, so that the flow remains consistent and the liquid doesn’t exceed the height of the filter paper.
• When the liquid flows from the funnel, make sure that it flows down the cup wall and goes all the way to the bottom. Another easy method is to tilt the beaker and attach the funnel to the side wall of the cup for hassle-free filtration.
• In order to increase the filtration rate, keep certain things in mind:
  • Avoid pressing the folds near the concentrated part, it may break the paper
  • Try to prevent dirt from getting to your hands before filtration, keep the filter paper upside down to avoid collecting dirt on the surface.
  • Pouring a hot solvent on the paper before hot filtration is also useful to increase the speed of filtration.

How to choose the best filter paper?

As mentioned above, filter papers are divided into qualitative and quantitative categories. Qualitative filter papers are known for the production of a higher amount of cotton fibres, therefore, these papers can be used for analysis where the residue collected is calculated.

On the other hand, quantitate filter papers are ash free and considered safe for applications that require superior resistance to chemical reactions. These kinds of filter papers are more suitable for special processing procedures.

The selection of the filter paper can be done on the basis of the decision that fewer impurities are accepted on not in the residual collected after filtration. Depending on the size of the crystal precipitates, one can use compact slow and medium speed filter papers. Ash less filter papers are more suited for Buechner funnels

Final words

Different types of filter papers are manufactured differently because they are used for different applications. Some filter papers are manufactured with extra thickness, some are renowned for excellent retention rate and faster filtration. One needs to understand the filtration speed to pick the most suitable option. Moreover, learning the correct way to fold and use filter paper is also crucial for optimal filtration. The correct procedure is discussed in this post, which will be helpful for individuals performing laboratory analysis using  filter paper.

Also Read: Litmus Paper - Everything you need to know