KNOWLEDGE SHARING ABOUT PAPER
1. What is Grammage?
This parameter relates to available surface area of paper or its weight. It is important due to several reasons: (i) It is the surface of paper that is used in nearly all its applications- be it writing, printing, packaging or tissue paper. (ii) Paper is sold on weight basis and the daily turnover of a mill is also indicated in units of weight.
What is Dimensional Stability?
Dimensional Stability is the ability of paper to retain its shape when subjected to varying degrees of temperature, moisture, pressure, or other stress. For example, the rate of absorption and de-absorption of moisture by paper affects its print quality. All papers expand with increased moisture content and contract with decreased moisture content and the extent of this change will vary from paper to paper.
What is Moisture?
Moisture is the amount of water present in the paper which is usually expressed as a percentage. Paper is made from a water suspension, or slurry, of fibres normally ranging in concentration or consistency from 0.5 to 1.0% solids. The thicker the slurry, the heavier will be the basis weight, or grammage, of the sheet of paper. Hence, the moisture content is important in calendaring, printing and converting.
What is Bulk?
Bulk is a term used to indicate the thickness of paper in relation to its weight.
What is Brightness?
Brightness is an attribute of visual perception in which a source appears to emit or reflect a given amount of light. It is a gauge of how well the lignin component of paper has been removed from the paper pulp and a means with which to measure the age of the paper. It is expressed as a percentage of the reflectance of blue light at a wavelength of 457 nm. The brightness of a piece of paper is typically expressed on a scale of 1 to 100 with 100 being the brightest. Papers with large amounts of residual lignin will have lower brightness.
What is Formation?
Formation describes the distribution of fibres and fillers across a sheet of paper. It is one of the most important parameters which effect other properties like Caliper, Opacity, Strength and Printing properties. For example, a glossy paper formation is caused by a non-uniform distribution of fibers in the paper, and in the extreme, this can result in poor, uneven printing and calligraphic reproduction.
What is Opacity?
Opacity is an attribute of how much light is kept away from passing through the sheet. It is an important parameter for printing paper and books.
What is Smoothness?
Smoothness is an attribute of the paper’s surface. It is important for writing as it affects the ease with which a pen can travel over the paper’s surface.