Paper that will receive a printed design, such as gift wrapping, requires a particular formula of sizing that will make the paper accept the printing properly.ģd Plants Made From Recycled Materials Pictures Pulp to paper A variety of sizings, generally rosins and gums, is available depending on the eventual use of the paper. A sizing such as starch makes the paper resistant to water-based ink (inks actually sit on top of a sheet of paper, rather than sinking in). Without any sizing at all, a paper will be too absorbent for most uses except as a desk blotter. Sizing affects the way the paper will react with various inks. These additives will influence the opacity and other qualities of the final product. At this point, various filler materials can be added such as chalks, clays, or chemicals such as titanium oxide. Inside a large tub, the pulp is subjected to the effect of machine beaters. 2 The pulp is next put through a pounding and squeezing process called, appropriately enough, beating.Bleach may be added at this stage, or colorings. The chips dissolve into pulp in the solution.
The chips are fed into the digester, and then boiled at high pressure in a solution of sodium hydroxide and sodium sulfide. This is done in huge vats called digesters. In the chemical process, wood chips from de-barked logs are cooked in a chemical solution. The pulp is filtered to remove foreign objects. The logs are then sent to grinders, which break the wood down into pulp by pressing it between huge revolving slabs.
In the mechanical process, logs are first tumbled in drums to remove the bark.
1 Several processes are commonly used to convert logs to wood pulp.Other materials used in paper manufacture include bleaches and dyes, fillers such as chalk, clay, or titanium oxide, and sizings such as rosin, gum, and starch.
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