Federation Of Paper Trader's Associations of India, Paper Testing Defects

General Defects in Paper:
Papermaking Has Heterogeneity : Papermaking, is a statistical process wherein furnish containing fibers, fines, colloidal suspensions and emulsions are spread on endless running wire, to form a sheet. Heterogeneity of furnish & process variables in sheet forming, pressing, drying, calendaring like winding, slitting, finishing, packing, transportation and storage are liable to develop some defects in paper. The defect in final product observed during inspection/quality control, can thus be classified from their point of origin viz
Defects due to furnish - composition like : Dirt Shives, Slivers Surface size Specks Spots due to dye, resin, starch Shadow marking Defects due to winding and slitting like : Uneven edges Adhesive tape adhering Slitter dust Hard or soft spots Loose edges Bump or dent on reel belly, deformation Scraps or sample cuts or snapping of paper Poor joint Rough slitting Wrinkles Baring or piping Waviness due to tension variation and joints Knife jumping, Telescopic due to loose paper/core Defects due to formation-effect of machine components like : Pin holes Wet streaks Wire line Water/Condensate dripping Felt crushing Dryer picking Seam marks Calendar stamping Hard and soft spots Air, bubbles, foam Surface and structural sidedness Dandy picking Fluff loose fibers Cloudy formation Calendar Blackening Uneven caliper, moisture, basis weigh Defects due to packing and storage : Dirt Piercing from floor before wrapping Cracked edges.
General Terminology used in defects of paper: Cockle : Local deformation of a sheet of paper due to unequal shrinkage giving a slightly crumpled appearance. Composition of Paper : Nature and proportions of the components fibrous and non-fibrous constituents of the paper, as determined by suitable analysis. Cooking : Treatment of fibrous raw material by heat in presence of water with added chemicals with or without pressure to product pulp. Contraries : Any visible matter that may be present and which is unwanted in the pulp (prior to stiff or stock preparation), stuff or paper under consideration . Crushing : Defect in paper , in the form of a local clotting caused by disturbances of the formation of already formed wet web by pressure or excessive moisture at the web end . Curl : Deformation of a sheet of paper or board, over all its surface which therefore tends to roll up into the form of a cylinder . Dusting : The separation of particles from the dry sheets by simple agitation or rubbing. Felt mark : Imprint left on the paper by the paper -machine felt due to the pressure of the felt in it . Fluff : Loose particles removed from the surface and the edges of paper by agitation or rubbing (see also dusting). Foam marks : A defect in paper caused by the presence of foam in the stock as it comes from the head box on to the paper wire machine. It is also called "Froth spots " . Rattle : The sound produce when a sheet of paper is shaken . It is used as a rough and ready method of judging quality . Show-through : The condition where printing on one side of the sheet can be seen from the other side when it is viewed by reflected light . Translucent paper (show-through) : Paper which permits the partial transmission of light but through which objects can be distinguish visually only when the paper is in direct contact with them. Two -Sidelines : An unlimited difference of varying degree in surface texture or shade existing between the two faces of a sheet of paper or board , which is inherent in the method of manufactures