"applied at an angle. When excess vertical pressure is applied on the lead, the lead is automatically retracted inwards. Higher-end mechanical pencils often feature a lead hardness grade indicator and sometimes feature a retractable lead guide pipe. This allows the lead guide pipe to retract back into the pencil body, which will keep it protected in storage and during transit and makes it 'pocket-safe'. In spite of the name, pencil leads do not contain the toxic chemical element lead, but are typically made with graphite and clay, or plastic polymers. Compared to standard pencils, mechanical pencils have a smaller range"
"for the outer coating could contain high concentrations of lead, and this could be ingested when the pencil was sucked or chewed. The lead of the pencil is a mix of finely ground graphite and clay powders. Before the two substances are mixed, they are separately cleaned of foreign matter and dried in a manner that creates large square cakes. Once the cakes have fully dried, the graphite and the clay squares are mixed together using water. The amount of clay content added to the graphite depends on the intended pencil hardness (lower proportions of clay makes the core softer),"
"and the amount of time spent on grinding the mixture determines the quality of the lead. The mixture is then shaped into long spaghetti-like strings, straightened, dried, cut, and then tempered in a kiln. The resulting strings are dipped in oil or molten wax, which seeps into the tiny holes of the material and allows for the smooth writing ability of the pencil. A juniper or incense-cedar plank with several long parallel grooves is cut to fashion a ""slat,"" and the graphite/clay strings are inserted into the grooves. Another grooved plank is glued on top, and the whole assembly is"
"below. The more common lead sizes are 0.5 mm and 0.7 mm, whose line widths provide a favourable balance between precision and strength. Less common lead sizes can range from 0.2 mm up to 5.6 mm. Pentel has also previously demonstrated a prototype 0.1 mm pencil. Pencils with sub-millimeter leads can usually hold multiple leads at the same time, reducing the frequency of refills. One exception was the Pentel 350 E, possibly Pentel's first mechanical pencil, which could only hold a single stick of 0.5 mm lead. Refill leads can be bought in small tubes and inserted into the barrel"
"a lead-based metal alloy that leaves dark markings on paper by abrading small pieces of core onto the surface. However, most modern ""lead pencils"" have a nonpoisonous core of greyish-black graphite mixed with various proportions of clay for consistency, enclosed within an outer wooden casing to protect the fragile graphite from being snapped apart or from leaving marks on the user's hand. White chalk has been traditionally used in schoolrooms to write on a main blackboard at the front of the room. In the 19th century, and indeed well into the 20th century, when paper was less readily available, individual"
"Yard-O-Led continues to produce fountain pens as well as pencils; most of which are made from hallmarked sterling silver. Yard-O-Led The Yard-O-Led Pencil Company was founded in London, England in 1934 by a Mr Brenner to produce his patent propelling pencils which contained twelve three inch leads (that is to say, 36 inches or a yard of lead). After the Second World War the company merged with Sampson Mordan Ltd whose founder had patented the first mechanical pencil in 1822. They built a new factory in Birmingham and took over Edward Baker Ltd, another pencil maker. Until 2015, the company"
"as needed. As with non-mechanical pencils, the leads of mechanical pencils are available in a range of hardness ratings, depending on the user's desired balance between darkness and durability. A commonly-used mechanical pencil lead is identical in density, but not in thickness to a traditional HB (US #2) pencil lead. Mechanical pencils with colored leads are less common, but do exist. Crayola's ""Twistable"" product line includes two different types of colored pencils (erasable and non-erasable) with mechanical feed mechanisms, but does not offer refill leads. Several companies such as Pentel, Pilot, and Uni-ball (Mitsubishi Pencil Co.) currently manufacture colored refill"
"what they call Nero pencils, which are similar in composition. Prismacolor also manufactures a lead-based black pencil that is very close in composition. Negro (lead pencil) Negro is the name of an artist's drawing medium, consisting of black pencil lead often encased in a wooden or paper tool. Its history and uses are common knowledge among illustrators and historians interested in illustrative art. The word ""Negro"", translates to ""black"" in Spanish and Italian, and is a term commonly used to describe artists' media and pigments that are black or dark in color. Negro lead was originally composed of a mixture"
"appear to be true.” Conté invented the modern pencil lead at the request of Lazare Nicolas Marguerite Carnot. The French Republic was at that time under economic blockade and unable to import graphite from Great Britain, the main source of the material. Carnot asked Conté to create a pencil that did not rely on foreign imports. After several days of research, Conté had the idea of mixing powdered graphite with clay and pressing the material between two half-cylinders of wood. Thus was formed the modern pencil. Conté received a patent for the invention in 1795, and formed la Société Conté"
"characterized by stainless steel shafts and hardened plastic grips. The 401 has the same stainless steel shaft with a rubber grip. Finally, the flagship pen, the 701 has a knurled grip and is completely stainless steel. A mechanism employed in the ""DelGuard"" system developed by Zebra, causes the lead sleeve in a mechanical pencil to extend outward when excessive pressure is applied at an angle. When excess vertical pressure is applied on the lead, the lead is automatically retracted inwards. Thus, the lead is protected (within certain limits) in both cases. In Japan, 0.3 and 0.7 versions of the DelGuard"
"barrel of the pencil. This was the most common type in the earlier part of the twentieth century. Many of these have a locking mechanism one way to allow the lead to be pushed back into the pencil. A clutch pencil (or leadholder) tends to use thicker leads (2–5.6 mm) and generally holds only one piece of lead at a time. A typical clutch pencil is activated by pressing the eraser cap on the top, to open the jaws inside the tip and allow the lead to freely drop through from the barrel (or back into it when retracting). Because"
"the lead falls out freely when the jaws are opened, its forward movement cannot be controlled except by external means. This can be easily done by keeping the tip of the pencil a few millimeters above a work surface or the palm of one's hand. Some clutch pencils do have mechanisms which incrementally advance the lead, such as the Alvin Tech-Matic leadholder, but these are not normally considered to be in the same category as most pencils with propelling mechanisms. Ratchet-based pencils are a variant of the clutch pencil, in which the lead is held in place by two or"
"tip so that the lead would not break as easily. Despite the original PD345 being widely replaced by the A variant, many users prefer it, finding it more comfortable and long lasting. Other classic designs from this period are the PS535 and the PS513. Pentel PD345 The Pentel PD345 is a mechanical pencil. It was first produced by Pentel in the 1980s, and is now available primarily online. Design features include a lead advance button on the side of the pencil body, a housing capable of holding dozens of leads at once, and a relatively wide eraser for heavy erasing."
"of marking types, though numerous variations exist. Most mechanical pencils can be refilled, but some inexpensive models are meant to be disposable and are discarded when empty. Mechanical pencil mechanisms use only a single lead diameter. Some pencils, such as the Pentel Function 357, place several mechanisms within the same housing, so as to offer a range of thicknesses (in this case three: 0.3, 0.5 and 0.7 mm). 1.00 mm leads also exist, but they are very rare. (See table below.) Different sizes of lead diameters are available to accommodate various preferences and pencil builds, as shown in the table"
"""The Poisoner's Poison"" and ""Inheritance Powder"" (alongside arsenic). Lead is a main-group element in the carbon group with the symbol Pb (from ) and atomic number 82. Lead is a soft, malleable other metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a liquid. Lead is used in building construction, lead-acid batteries, bullets and shots, weights, as part of solders, pewters, fusible alloys and"
"Koh-i-Noor Hardtmuth Koh-i-Noor Hardtmuth a.s. is a Czech manufacturer and one of the world's largest producers and distributors of art supplies, writing equipment and stationery. It was founded in 1790 by Joseph Hardtmuth of Austria. In 1802, the company patented the first pencil lead made from a combination of kaolin and graphite. In 1848, Joseph's sons, Karl and Ludwig, took over the family business, and the production was relocated to the Bohemian town of Budweis, within the current Czech Republic. The products were given awards in many world exhibitions, including in 1855 in New York City, 1856, 1900 and 1925"
"end. These can be divided into two groups: propelling pencils use an internal mechanism to push the lead out from an internal compartment, while clutch pencils merely hold the lead in place (the lead is extended by releasing it and allowing some external force, usually gravity, to pull it out of the body). The erasers (sometimes replaced by a sharpener on pencils with larger lead sizes) are also removable (and thus replaceable), and usually cover a place to store replacement leads. Mechanical pencils are popular for their longevity and the fact that they may never need sharpening. Lead types are"
"Yard-O-Led The Yard-O-Led Pencil Company was founded in London, England in 1934 by a Mr Brenner to produce his patent propelling pencils which contained twelve three inch leads (that is to say, 36 inches or a yard of lead). After the Second World War the company merged with Sampson Mordan Ltd whose founder had patented the first mechanical pencil in 1822. They built a new factory in Birmingham and took over Edward Baker Ltd, another pencil maker. Until 2015, the company was part of the Letts Filofax Group, and has now re-established itself as Imperial Yard Ltd. Under this brand,"
"Minium (pigment) Minium, also known as red lead, is a bright orange red pigment that was widely used in the Middle Ages for the decoration of manuscripts and for painting. It was made by roasting white lead pigment in the air; the white lead would gradually turn yellow, then into an orange lead tetroxide. The color varied depending upon how long the mineral was roasted. During the Roman Empire, the term minium could refer either to the pigment made from ground cinnabar or to the less expensive red lead. The name came from the river Minius in Iberia (now forming"
"to distinguish between this and ""true"" ""pastiglia"", or white lead pastiglia which is defined as being made from white lead powder, made by combining powdered lead and vinegar in an anaerobic environment, bound with egg white. White lead bound with oil or egg yolk was also the most common pigment for white paint. White lead pastiglia is very delicate and used for small areas only, but can produce very fine detail. It was mainly used on small caskets and boxes. Sections were typically pre-moulded, doubtless from metal matrices to judge from the crisp detail, and glued on when hard. This"
"Negro (lead pencil) Negro is the name of an artist's drawing medium, consisting of black pencil lead often encased in a wooden or paper tool. Its history and uses are common knowledge among illustrators and historians interested in illustrative art. The word ""Negro"", translates to ""black"" in Spanish and Italian, and is a term commonly used to describe artists' media and pigments that are black or dark in color. Negro lead was originally composed of a mixture of wax and charcoal and was often used in combination with heavily textured coquille paper. The intention was to create sturdy pencil line"
"result. Paper or plastic surfaces require their own lead types. In most cases, the final drawings are drawn with ink, on either plastic or tracing paper. The pen is generally a Rapidograph-type technical pen, a marker pen that draws lines of consistent width (so-called steel marker pen). The pen has an ink container which contains a metal tube, inside which is a thin metal needle or wire, the soul. Ink is absorbed between the needle and the tube wall, preventing an excessive amount of ink from being released. The needle has a weight and by waving the pen back and"
"of sound studios. Organ pipes are often made from a lead alloy, mixed with various amounts of tin to control the tone of each pipe. Lead is an established shielding material from radiation in nuclear science and in X-ray rooms due to its denseness and high attenuation coefficient. Molten lead has been used as a coolant for lead-cooled fast reactors. The largest use of lead in the early 21st century is in lead–acid batteries. The reactions in the battery between lead, lead dioxide, and sulfuric acid provide a reliable source of voltage. The lead in batteries undergoes no direct contact"
"three small jaws inside a ring at the tip. The jaws are controlled by a button on the end or the side of the pencil. When the button is pushed, the jaws move forward and separate, allowing the lead to advance. When the button is released and the jaws retract, the ""lead retainer"" (a small rubber device inside the tip) keeps the lead in place, preventing the lead from either falling freely outward or riding back up into the barrel until the jaws recover their grip. Other designs use a precisely-fitted metal sleeve to guide and support the lead, and"
"Diachylon Diachylon (from Latin ""diachȳlōn"", representing Greek ', ""[a medicament] composed of juices""), also rendered diachylum or diaculum""', was originally a kind of medicament made of the juices of several plants (thus its name), but now commonly the name for lead-plaster, ""emplastrum plumbi""—a plaster made of lead oxide boiled together with olive oil and water. It is applied to sheets of linen, and works as an adhesive plaster when heated. Historically, several different types of diachylons have been described. White, or simple, diacyhlon is compounded of common oil, litharge of gold (litharge mixed with red lead), and adhesives drawn from"
"do not need a rubber retainer. In one type of ratchet-based pencil (developed by Tombow Pencil Co.), shaking the pencil back and forth causes a weight inside the pencil to operate a mechanism in the cap. A button may be present on the top or side of the pencil, to allow the user to advance the lead manually when necessary. Another variation advances the lead automatically. In this design, the lead is advanced by a ratchet but only prevented from going back into the pencil, just held from falling by a small amount of friction. The nib is a spring-loaded"
"to emphasize them. He will use photographic reference when appropriate, as when he draws things that he is not accustomed to. Because a significant portion of his income is derived from selling his original artwork, he is reluctant to learn how to produce his work digitally. Artist Jim Lee is known to use F lead for his pencil work. Artist J. Scott Campbell does his pencil with a lead holder, and Sanford Turquoise H lead, which he uses for its softness and darkness, and for its ability to provide a ""sketchy"" feel, with a minimal amount of powdery lead smearing."
"Lead paint Lead paint or lead-based paint is paint containing lead. As pigment, lead(II) chromate (Pb Cr O, ""chrome yellow""), Lead(II,IV) oxide, (Pb O, ""red lead""), and lead(II) carbonate (Pb C O, ""white lead"") are the most common forms. Lead is added to paint to accelerate drying, increase durability, maintain a fresh appearance, and resist moisture that causes corrosion. It is one of the main health and environmental hazards associated with paint. In some countries, lead continues to be added to paint intended for domestic use, whereas countries such as the U.S. and the UK have regulations prohibiting this, although"
"pencil. There is a wide range of grades available, mainly for artists who are interested in creating a full range of tones from light grey to black. Engineers prefer harder pencils which allow for a greater control in the shape of the lead. Manufacturers distinguish their pencils by grading them, but there is no common standard. Two pencils of the same grade but different manufacturers will not necessarily make a mark of identical tone nor have the same hardness. Most manufacturers, and almost all in Europe, designate their pencils with the letters ""H"" (commonly interpreted as ""hardness"") to ""B"" (commonly"
"broadened the testing to 400 lipsticks that were available on the U.S. market at the time. This study was done by Frontier Global Sciences, Inc. using the same testing method as 2009. This study found an average of 1.11 ppm compared to the 1.07 ppm average in the 2009 study. The maximum lead level found was 7.19 ppm in Maybelline’s Color Sensational 125 – Pink Petal. This is over two times the maximum limit found in the 2009 study. Lead is not listed as an ingredient in lipstick, but trace amounts can be found in the mineral based additives. Lead"
"away during work. The following table lists the prominent manufacturers of wood-cased (including wood-free) pencils around the world. Pencil A pencil is an implement for writing or drawing constructed of a narrow, solid pigment core inside a protective casing which prevents the core from being broken and/or from leaving marks on the user’s hand during use. Pencils create marks by physical abrasion, leaving behind a trail of solid core material that adheres to a sheet of paper or other surface. They are distinct from pens, which instead dispense liquid or gel ink onto the surface being marked. Most pencil cores"
"Pentel PD345 The Pentel PD345 is a mechanical pencil. It was first produced by Pentel in the 1980s, and is now available primarily online. Design features include a lead advance button on the side of the pencil body, a housing capable of holding dozens of leads at once, and a relatively wide eraser for heavy erasing. Due to the side mounted lead advance button, the pencil was marketed as the ""Quicker Clicker"" as the user didn't have to stop writing to advance the lead. The successor to this pencil is the PD345-A with a wider, ""ergonomic"" grip and a redesigned"
"pure linseed oil, and in this form is supplied to the painter. Barium sulfate is the chief adulterant used in the manufacture of white lead. White lead has greater covering properties and is more durable than the other bases. Paints having white lead for a base darken with age, and become discolored when exposed to hydrogen sulfide, which exists to a greater or lesser extent in the air of all large towns. Zinc white, zinc oxide, is of a purer white color than white lead. It is lighter, but does not possess the same durability or covering power. It is,"