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Ink Eraser
An ink eraser is an instrument used to scrape away or chemically bleach ink from a writing surface. This is a more involved process than removing pencil markings. Pencil marks can be gradually adhered to natural rubber fragments by rubbing the mark with a pencil eraser (this action is what prompted Joseph Priestley to give solidified latex its Natural rubber, common name). Ink, however, readily penetrates the fibers of most papers and is therefore more difficult to extract by mechanical action. Older ink erasers are therefore small knives designed to scrape off the top few microns of a sheet of paper, removing the ink that had penetrated. In concert with bladed ink erasers, an eraser similar to those at the end of pencils was also used, with additional abrasives, such as sand, mixed into the rubber. Fibreglass ink erasers also work by abrasion. These erasers physically remove the ink and the paper it has marked from the larger sheet. The chemical ink eradicator contains a subst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelikan
Pelikan Holding AG is a German manufacturing company of writing, office and art equipment. Credited with the invention of the differential-piston filling method, the original company was founded in Hanover in 1838 before it went bankrupt and restarted. Through a reverse takeover on 8 April 2005, Pelikan Holding AG is now an Aktiengesellschaft company (limited by share (finance), shared ownership), part of the Pelikan Group Gesellschaft mit beschränkter Haftung, GmbH. Pelikan manufactures a wide range of products including writing implements, list of art media, art materials and office goods. History The roots of the company can be traced to 1838, when chemist Carl Hornemann founded a paint and ink factory in Hanover, Germany. The date of the first price list of the company, 28 April, is set as the company's foundation date. In 1863, Guenther Wagner obtained the position of chemist and plant manager. He took over the company in 1871. Wagner also designed the company's fir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Writing Implements
A writing implement or writing instrument is an object used to produce writing. Writing consists of different figures, lines, and or forms. Most of these items can be also used for other functions such as painting, drawing and technical drawing, but writing instruments generally have the ordinary requirement to create a smooth, controllable wikt:line, line. Another writing implement employed by a smaller population is the stylus used in conjunction with the Slate and stylus, slate for punching out the dots in Braille. Autonomous An autonomous writing implement is one that cannot "run out"—the only way to render it useless is to destroy it. Without pigment The oldest known examples were created by incising a flat surface with a rigid tool rather than applying pigment with a secondary object, e.g., Chinese jiaguwen carved into turtle shells. However, this may simply represent the relative durability of such artifacts rather than truly representing the evolution of techniques, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eraser
An eraser (also known as a rubber in some Commonwealth countries, including South Africa from which the material first used got its name) is an article of stationery that is used for removing marks from paper or skin (e.g. parchment or vellum). Erasers have a rubbery consistency and come in a variety of shapes, sizes, and colors. Some pencils have an eraser on one end. Less expensive erasers are made from synthetic rubber and synthetic soy-based gum, but more expensive or specialized erasers are made from vinyl, plastic, or gum-like materials. At first, erasers were invented to erase mistakes made with a pencil; later, more abrasive ink erasers were introduced. The term is also used for things that remove marks from chalkboards and whiteboards. History Before rubber erasers used today, tablets of wax were used to erase lead or charcoal marks from paper. Bits of rough stone such as sandstone or pumice were used to remove small errors from parchment or papyrus documents ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deinking
Deinking is the industrial process of removing printing ink from paperfibers of recycled paper to make deinked pulp. The key in the deinking process is the ability to detach ink from the fibers. This is achieved by a combination of mechanical action and chemical means. In Europe the most common process is froth flotation deinking. Paper is one of the main targets for recycling. A concern about recycling wood pulp paper is that the fibers are degraded with each cycle and after being recycled 4–6 times the fibers become too short and weak to be useful in making paper. History Before the invention of the paper machine in 1799 the most common fibre source was recycled fibres from used textiles, hence the name rag paper. The rags were from hemp, linen and cotton. It was not until the introduction of wood pulp in 1843 that paper production was independent of recycled materials. Recycling of used paper before the industrialisation of paper production, rag paper was recycled to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldehyde
In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are a common motif in many chemicals important in technology and biology. Structure and bonding Aldehyde molecules have a central carbon atom that is connected by a double bond to oxygen, a single bond to hydrogen and another single bond to a third substituent, which is carbon or, in the case of formaldehyde, hydrogen. The central carbon is often described as being sp2- hybridized. The aldehyde group is somewhat polar. The bond length is about 120–122 picometers. Physical properties and characterization Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes such as formaldehyde and acetaldehyde are solubl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon
Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. Carbon makes up about 0.025 percent of Earth's crust. Three Isotopes of carbon, isotopes occur naturally, carbon-12, C and carbon-13, C being stable, while carbon-14, C is a radionuclide, decaying with a half-life of 5,700 years. Carbon is one of the timeline of chemical element discoveries#Pre-modern and early modern discoveries, few elements known since antiquity. Carbon is the 15th abundance of elements in Earth's crust, most abundant element in the Earth's crust, and the abundance of the chemical elements, fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon's abundance, its unique diversity of organic compounds, and its unusual abi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxide
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. The corresponding electrically neutral compound HO• is the hydroxyl radical. The corresponding covalently bound group of atoms is the hydroxy group. Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry. Many inorganic substances which bear the word ''hydroxide'' in their names are not ionic compounds of the hydroxide ion, but covalent compounds which contain hydroxy groups. Hydroxide ion The hydroxide ion is naturally produced ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfite
Sulfites or sulphites are compounds that contain the sulfite ion (systematic name: sulfate(IV) ion), . The sulfite ion is the conjugate base of bisulfite. Although its acid (sulfurous acid) is elusive, its salts are widely used. Sulfites are substances that naturally occur in some foods and the human body. They are also used as regulated food additives. When in food or drink, sulfites are often lumped together with sulfur dioxide.SeREGULATION (EU) No 1169/2011 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL/ref> Structure The structure of the sulfite anion can be described with three equivalent resonance structures. In each resonance structure, the sulfur atom is double-bonded to one oxygen atom with a formal charge of zero (neutral), and sulfur is singly bonded to the other two oxygen atoms, which each carry a formal charge of −1, together accounting for the −2 charge on the anion. There is also a non-bonded lone pair on the sulfur, so the structure predicted by VSEPR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Blue
Royal blue is a deep and vivid shade of blue. It is said to have been created by a consortium of mills in Rode, Wiltshire (in Somerset as of 1937), which won a competition to make a robe for Queen Charlotte, consort of King George III. In winning the prize, a business in the village invented the dye and received a certificate to sell it under that name. Brightness The ''Oxford English Dictionary'' defines "royal blue" as "a deep vivid blue", while the '' Cambridge English Dictionary'' defined it as "a strong, bright blue colour", and the ''Collins English Dictionary'' defines it as "a deep blue colour". US dictionaries give it as further towards purple, e.g. "a deep, vivid reddish or purplish blue" (''Webster's New World College Dictionary'') or "a vivid purplish blue" (''Merriam-Webster''). By the 1950s, many people began to think of royal blue as a brighter color, and it is this brighter color that was chosen as the web color "royal blue" (the web colors when they wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pointe Effaceur
Pointe technique ( ) is part of classical ballet involving a technique that concerns ''pointe work'', in which a ballet dancer supports all body weight on the tips of fully extended feet when wearing pointe shoes. A dancer is said to be ''en pointe'' () when the body is supported in this manner, and a fully extended vertical foot is said to be ''en pointe'' when touching the floor, even when not bearing weight. Pointe technique resulted from a desire for female dancers to appear weightless and sylph-like. Although both men and women are capable of pointe work, it is most often performed by women. Extensive training and practice are required to develop the strength and technique needed for pointe work. Typically, dance teachers consider factors such as age, experience, strength and alignment when deciding whether to allow a dancer to begin pointe work. Technique Pointe technique encompasses both the mechanical and artistic aspects of pointe work. In particular, it is concerned ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Priestley
Joseph Priestley (; 24 March 1733 – 6 February 1804) was an English chemist, Unitarian, Natural philosophy, natural philosopher, English Separatist, separatist theologian, Linguist, grammarian, multi-subject educator and Classical liberalism, classical liberal Political philosophy, political theorist. He published over 150 works, and conducted experiments in several areas of science. Priestley is credited with his independent discovery of oxygen by the thermal decomposition of mercuric oxide, having isolated it in 1774. During his lifetime, Priestley's considerable scientific reputation rested on his invention of carbonated water, his writings on electricity, and his discovery of several "airs" (gases), the most famous being what Priestley dubbed "dephlogisticated air" (oxygen). Priestley's determination to defend phlogiston theory and to reject what would become the chemical revolution eventually left him isolated within the scientific community. Priestley's science was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
