Paper Density

The paper density of a type of paper or cardboard is the collection of the product per unit of area. Two ways of expressing paper density are usually used:

* Expressed in grams per square metre (g/m²), paper density is also called as grammage. This is the evaluate used in most parts of the world.

* Expressed in conditions of the mass (in pounds) of a ream of 500 (or in some cases 1000) sheets of a specified (raw, still uncut) basis size, paper density is called as basis weight. The base size and area used here based on the product type. This convention is used in the United States, and (to a lesser degree) in a very little number of other countries that use United States paper sizes. Japanese paper is articulated as the weight in kg of 1000 sheets.

Photographic Paper

Until the beginning of digital photographic processes, the sole meaning of photographic paper was paper coated with light-sensitive chemicals.

So-called photo papers of today are often especially coated papers for use in inkjet or laser printers to make digital prints. This article focuses on conventional photographic papers.

Photographic paper may be showing to light in a controlled manner either by placing a negative in contact with the paper directly (contact printing) or by using an enlarger (enlarging) in order to create a latent image. Photographic papers are subsequently developed using wet chemicals to make a visible image.

Obsolete And Special-Purpose Printing Technologies

The following technologies are either obsolete, or limited to particular applications though most were, at one time, in widespread use.

Thermal printers work by selectively heating regions of particular heat-sensitive paper. These printers are limited to special-purpose applications such as money registers and the printers in ATMs and gasoline dispensers. They are also used in some older reasonably priced fax machines.

Impact printers rely on a forcible impact to transfer ink to the media, like to the action of a typewriter. All but the dot matrix printer rely on the use of shaped characters, letterforms that represent each of the characters that the printer was capable of printing. In addition, most of these printers were restricted to monochrome printing in a single typeface at one time, although bolding and underlining of text could be done by overstriking, that is, printing two or more impressions in the same character position. Impact printers varieties contain, Typewriter-derived printers, Teletypewriter-derived printers, Daisy wheel printers, Dot matrix printers and Line printers. Dot matrix printers remain in general use in businesses where multi-part forms are printed, such as car rental service counters.

The real facts about Earth

The Earth's surface is exceptionally young. In the relatively short (by astronomical standards) time of 500,000,000 years or so erosion and tectonic processes destroy and restructure most of the Earth's surface and thus eliminate almost all traces of earlier geologic surface history (such as impact craters). Thus the very before time on history of the Earth has mostly been erased. The Earth is 4.5 to 4.6 billion years old, but the oldest recognized rocks are about 4 billion years aged and rocks older than 3 billion years are rare. The oldest fossils of presented organisms are less than 3.9 billion years old. There is no evidence of the critical period when life was first getting in progress.

The Earth's environment is 77% nitrogen, 21% oxygen, with draws of argon, carbon dioxide and water. There was perhaps a very much bigger amount of carbon dioxide in the Earth's atmosphere when the Earth was first created, but it has since been nearly all incorporated into carbonate rocks and to a smaller extent dissolved into the oceans and consumed by living plants. Plate tectonics and biological processes now keep a frequent flow of carbon dioxide from the atmosphere to these various "sinks" and back over again. The little amount of carbon dioxide occupant in the atmosphere at any time is very important to the maintenance of the Earth's surface temperature through the greenhouse effect. The greenhouse consequence raises the average surface temperature regarding 35 degrees C above what it would if not be (from a frigid -21 C to a comfortable +14 C); without it the oceans would freeze and life as we know it would be impossible.