HAWACH filter paper is well-known for its high quality, trustworthiness, and everything for the purpose of customers. To ensure consistent high quality and uniformity, HAWACH selects high-quality natural materials for filter paper production. Before leaving the factory, each filter paper undergoes rigorous testing in terms of packaging weight, thickness, gas flow rate, and mechanical strength. In addition, individual parameters such as particle retention, capillary action rate, filtration characteristics, and apparent characteristics can also be measured as required.
Qualitative filter paper
The right choice of filter paper is the key to the success of laboratory filtration. Among the range of filter papers to meet all the needs, qualitative filter paper is the popular choice for general purpose separations that need high purity and consistent performance.
Made of 100 % high-quality cotton linters, qualitative filter papers are qualified to have alpha-cellulose content of > 98 %. With the highest degree of polymerization, alpha-cellulose is proved to be the most stable cellulose form. Furthermore, the process of acid-washing makes the qualitative filter papers ashless and high purity.
During the qualitative cellulose filtering separations, particulate will be entrapped within the cellulose fibers deep in the media. First, qualitative filter papers are widely used not only in qualitative analytical separations for precipitates and buffers filtration which require the determination and identification of particulate in both liquids and gas, but for soil analysis, food, and beverage testing. The filter paper made of natural fiber is also a common tool for liquids clarification.
With a higher percentage of alpha-cellulose than other filter papers, qualitative filter papers will weaken when they are handled with water. So, if you are doing the filtration under the wet or vacuum condition, qualitative filter papers are not recommended.
Qualitative filter paper generally adopts gravity filtration, which uses filter paper to trap solid-phase particles to separate the solid-liquid. The filter paper has natural mechanical strength and certain toughness. If you need to speed up the filtering speed, you can fold the filter paper several times (such as stacking two layers of filter paper into a fan shape or a zigzag pattern) to increase the filtering speed.
There are standard and wet-strength qualitative filter papers. The standard one is the most widely used and oldest chemical analysis filter paper, with medium retention capacity and flow rate. The speed and retention capacity of wet-strength qualitative filter paper is medium and can be humidified by a ventilator or other applications requiring high-strength. It adopts portable packaging, which can be directly hung on the wall or placed on a workbench and can also be placed vertically or flat on a shelf for easy removal one by one. Both large and small packages are clearly marked with the size and quantity.
The specifications of HAWACH qualitative filter paper cover round filter paper with a diameter of 47mm-185mm(70，90, 10,125,150,180, 55,47 and185), and square filter paper with a diameter of 60×60, 41x45mm, which cover most of the laboratory application range and are often used for liquid clarification. For the qualitative analysis and separation of traditional sediments, such as calcium oxalate, lead sulfate, and calcium carbonate, it is often used.
It is a standard filter paper for the determination of cellulase activity, drilling fluid active clay, protective cloth resistance, penicillin, and solid waste chlorinated herbicides. In the food industry, filter paper is often used to separate solid food or extract liquids from related liquids and is also widely used in simple qualitative analysis and separation in teaching. For air pollutant monitoring, there are discs and rolls of filter paper available to collect atmospheric dust from the atmosphere and then use a photometer to measure the degree of pollution.