Chalkboard

picture info	Chalkboard A blackboard (also known as a chalkboard) is a reusable writing surface on which text or drawings are made with sticks of calcium sulphate or calcium carbonate, known, when used for this purpose, as chalk. Blackboards were originally made of smooth, thin sheets of black or dark grey slate stone. Design A blackboard can simply be a board painted with a dark matte paint (usually black, occasionally dark green). Matte black plastic sign material (known as closed-cell PVC foamboard) is also used to create custom chalkboard art. Blackboards on an A-frame are used by restaurants and bars to advertise daily specials. A more modern variation consists of a coiled sheet of plastic drawn across two parallel rollers, which can be scrolled to create additional writing space while saving what has been written. The highest grade blackboards are made of a rougher version porcelain enamelled steel (black, green, blue or sometimes other colours). Porcelain is very hard wearing, and blackboar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Chalkboard Art Chalkboard art or chalk art is the use of chalk on a blackboard as a visual art. It is similar to art using pastels and related to sidewalk art that often uses chalk. Chalkboard art is often used in restaurants, shops or walls. Characteristics Chalkboard art is ephemeral. Chalkboard artists Chalkboard artists include Catherine Owens Katherine, also spelled Catherine, and other variations are feminine names. They are popular in Christian countries because of their derivation from the name of one of the first Christian saints, Catherine of Alexandria. In the early Chris ..., Chris Yoon, Maggie Choate, Bryce Wisdom, C. J. Hughes, Scrojo. References Sources Visual arts media {{art-technique-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Chalkboard Scraping Scraping a chalkboard (also known as a blackboard) with one's fingernails produces a sound and feeling which most people find extremely irritating. The basis of the innate reaction to the sound has been studied in the field of psychoacoustics (the branch of psychology concerned with the perception of sound and its physiological effects). Physiological response Brain stem reflex In response to audio stimuli, the mind's way of interpreting sound can be translated through a regulatory process called the reticular activating system. Located in the brain stem, the reticular activating system continually listens, even throughout delta-wave sleep, to determine the importance of sounds in relation to waking the cortex or the rest of the body from sleep. Chalkboard scraping, or noises that elicit an emotional response have been known to trigger tendencies from the fight or flight response which acts as the body's primary self-defense mechanism. Emotional response Distinct emotion A stu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Chalkboard Eraser A chalkboard eraser is a special type of eraser specifically used to erase chalk markings on slating paint (used on chalkboards and slates). It is most commonly made of felt strips attached to a handle. Chalkboard erasers are typically broad and rectangular, intended to clear large areas for new content as part of a lecture or presentation. History Chalkboard erasers were invented around 1863 by John L. Hammett, who owned some stores that sold and created school products in Rhode Island and then later in Boston. Mostly slates were sold there as well as chalk and so on. At the time, rags or old cloths were used to erase and get rid of the chalk markings on slates in schools, offices, and for the most part, everywhere. Hammett created the chalkboard before the invention of the chalkboard eraser by creating ''slating paint''. Hammett then, during a presentation on his chalkboard "discovered" that wool felt strips wiped off the chalk writing better than rags. Following this discovery h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Whiteboards A whiteboard (also known by the terms marker board, dry-erase board, dry-wipe board, and pen-board) is a glossy, usually white surface for making non-permanent markings. Whiteboards are analogous to blackboards, but with a smoother surface allowing for rapid marking and erasing of markings on their surface. The popularity of whiteboards increased rapidly in the mid-1990s and they have become a fixture in many offices, meeting rooms, school classrooms, and other work environments. The term ''whiteboard'' is also used metaphorically in reference to features of computer software applications that simulate whiteboards. Such "virtual tech whiteboards" allow one or more people to write or draw images on a simulated canvas. This is a common feature of many virtual meeting, collaboration, and instant messaging applications. The term ''whiteboard'' is also used to refer to interactive whiteboards. History Photographer Martin Heit and Alliance employee Albert Stallion have been cre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Slate Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. Foliation may not correspond to the original sedimentary layering, but instead is in planes perpendicular to the direction of metamorphic compression. The foliation in slate is called "slaty cleavage". It is caused by strong compression causing fine grained clay flakes to regrow in planes perpendicular to the compression. When expertly "cut" by striking parallel to the foliation, with a specialized tool in the quarry, many slates will display a property called fissility, forming smooth flat sheets of stone which have long been used for roofing, floor tiles, and other purposes. Slate is frequently grey in color, especially when seen, en masse, covering roofs. However, slate occurs in a variety of colors even from a single locality; for ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]