Paper and Board
wood is made up of cellous fibres that are bounded together by lignin. in order to produce paper , these fibres must be seperated from one another to form a mass individual fibres called wood pulp.
the logs of coniferous trees are saturated with water and de-barked. the wood is ground down. this softens the lignin and the mechanised forces seperate fibres to form groundwood pulp. this pulp is screened to accept 1-2mm pieces with larger pieces being re-circulated for additional screening.
After de-barking hard and soft wood logs are cut into 2cm chips along the grain. these are pounded into fragments and are screened. the resulted pulp is stored and treated with either acid or alkali to break down the lignin.
starts with the wood pulp diluted to 99% water and 1% fibre. a continous stream of slurry is pumped through an ajustible slit onto a moving guaze wire belt that vibrates to drain off some of the water and allow the fibres to interweave.
nip presses or rollers that wring out the majority of excess water from the pulp and stretches out into a rough paper.
dries the paper using a series of steam-heated rollers by removing the moisture.
paper is fed into a series of rollers to smooth it out and give it a thickness. the amount of pressure determines the finish of the paper.
contains mainly ferrite or iron. almost all are magnetic
contains no iron. not magnetic
Formed by mixing two or more metals.