Paper trail

1.Logs are cut to even-sized wood chips.

2. Wood chips are cooked with caustic soda (sodium hydroxide) at high temperature to separate lignin (the natural glue which holds wood fibres together) from cellulose in the pulp. A liquid residue, black liquor, is recovered to retrieve used chemicals and burned to generate steam and power.

3. Unbleached pulp is refined in a series of washers and screens.

4. Pulp is bleached in a sequence of treatments lasting as long as 15 hours. The Elemental Chlorine Free bleaching process uses oxygen, chlorine dioxide and hydrogen peroxide to whiten the pulp.

5. Bleached pulp is blended with various additives and chemicals.

i. Fillers and coatings: Clay, calcium carbonate (chalk) and titanium oxide are added to enhance paper opacity, whiteness and smoothness.

ii. Sizing agents: Starch, resin, alum, gelatine or latex are used to increase water repellence, prevent ink blotting and reduce fibre dust, which can clog printing machinery.

iii. Biocides: To prevent bacterial growth in the pulp and finished paper products.

6. Blended wet pulp is drained through a moving belt of woven nylon mesh to form thick mats. Next, a series of presses remove more water and thins the sheets. Steam-heated dryers dry the sheets.

7. The paper sheets are rolled into bales, sprayed with starch to obtain a smooth, glossy surface and then passed through a calender to be scrubbed into even thickness.

8. Jumbo reels of white paper are cut to size.