Before reaching the handsheet former, the pulp goes through several steps. This blog throws light on those steps.
What is a handsheet?
As per the TAPPI standard T 205, a handsheet is a circular sheet of paper made by a hand process. Handsheets are prepared to determine the quality of paper achieved from a particular stock of pulp. The steps involved in the hand sheet-making include:
Cleaning of the raw material or Removing the impurities
Cotton waste purification
Cutting, soaking, and drying of fibres
Pulp Refining
Preparation of feedstock
Handsheet preparation
Let us learn about the process in detail in the following section.
Steps Involved In Hand Sheet Making Process
Cleaning of the raw material or Removing the impurities
The goal of cleaning is to remove impurities, fine seeds, contaminants, bird feathers, leafy particles, etc. from the cotton waste. This cleaning process is undertaken both manually and via a cleaning machine for effective purification. The machine contains blades and a perforated body responsible for cutting off the particles.
Cotton waste purification
Before the pulp can be sent to the handsheet former, it must also be purified. The purification of cotton waste, with the help of chemicals, takes place in this step. These chemicals are capable of removing proteins, inorganic salts, pigments, resins, wax, and other impurities from the cotton fibres. The intensity of impurities in the fibres depends on the type of cotton, origin, agricultural conditions, maturity, and wear and tear. The user measures the length, strength, and diameter of the fibre once the purification is done.
Cutting, soaking, and drying of fibres
The purified raw material is then cut into long fibres. They are then beaten in a hot water container, where the fibrillation takes place. Once this is done, the fibres are soaked with water and drained out to let them dry.
Pulp Refining
The next step of refining shortens, straightens, and swells the fibres. It is in this process, that internal fibrillation takes place and also fines are formed in the Hollander beater. The refined pulp is further sent for bleaching.
Handsheet preparation
Once the pulp is refined, beaten, and bleached, the pulp is sent to the handsheet former for the preparation of circular sheets. In this machine, the sheets are prepared in a laboratory setting and as per commercial production. As soon as the sheets are formed in this machine, they are sent to the paper press machine where they are dewatered, dried and pressed. The prepared sheets are carefully separated from the blotting paper for further examination and tests.
Conclusion
The drying and pressing of handsheets via a paper press machine are as important as their production using a handsheet former. Hence, if manufacturers are planning to invest in the sheet-making machine then they must not forget to consider the pressing machine for the effective completion of the process.
At UEC, you can find the best and highest quality paper-making machines at competitive prices. Visit the website to explore them and get in touch with the experts to learn more about them.