STEAM VOCABULARY GUIDE
STEAM VOCABULARY GUIDE
Arts Institutes and the Lawrence Arts Center Taught by professional artists, the Lawrence Arts Center Art Institutes program offers a place for young people to immerse themselves in an environment to research new concepts, put ideas into practice, discover art outside of academics, learn new skills, explore innovative techniques and envision their future. Art Institutes offer instruction in visual arts, dance, theater, and digital media for beginners through advanced students in an accepting, inspired, creative atmosphere. In addition to developing artistic skill, the focus is on building initiative, self-direction, productivity and leadership, with support to make the real world connections that young people need to succeed. In an effort to connect studio practice with the science, technology, engineering and math concepts employed in the arts, the Lawrence Arts Center developed this science instructional guide for art instructors working with students in 6th-12th grades. This guide is intended to provide a foundation for lesson plans and classroom materials, to expand how young people understand the connections between science, art and innovation.
Arts Institutes Innovation Team MARGARET WEISBROD MORRIS Chief Program Officer, Lawrence Arts Center
JESSICA CONNER Art Educator, Shawnee Mission Public Schools
NEAL BARBOUR Director of Youth Education, Lawrence Arts Center
JOSHUA CONNER Science Teacher, Olathe Public Schools
LAURIE MCLANE HIGGINSON Education Curator, Lawrence Arts Center
ANN FOSTER Science Teacher, Lawrence Public Schools
KYLA STRID Director of Residencies and Adult Education, Lawrence Arts Center
HANNAH HURST Art Educator, Lawrence Public Schools
RACHEL VON WAGONER Studio Manager, Lawrence Arts Center ASHELY BOYACK Dance Educator, University of Utah
LARRY MITCHELL Actor & Playwright GRACE PETERSON Visual Arts Coordinator, Salina Arts & Humanities
The mission of the Lawrence Arts Center is to enrich individuals and the community by nurturing love of the arts through exhibitions, performance, and arts education. The Arts Center has been serving the community of Lawrence, Kansas since 1975 with arts programs and services for individuals of all ages, interests and backgrounds. All material in this book is subject to copyright and cannot be reproduced without permission of the Lawrence Arts Center. However, the Lawrence Arts Center seeks to actively support the STEAM movement everywhere. If you are interested in learning more about the ideas or materials in this booklet, the Arts Institutes programming, or how to start a program in your area, contact Margaret Weisbrod Morris, margaret@lawrencearstcenter.org.
CALL 785.843.2787
BROWSE lawrenceartscenter.org
VISIT 940 New Hampshire Street, Lawrence, KS 66044
CERAMICS
CERAMICS
Ceramics Clay: the feldspar group of minerals comprise around 60% of the earth’s crust. They are aluminum silicates, also incorporating alkali and/ or alkaline earth metals. Over the geological timescale a great deal of feldspar has been eroded through a weathering process, mainly through the action of water such as rivers. Although these rocks seem solid and eternal, over millions of years the effect of rain dissolves some of the alkali and alkaline earth metal oxides leaving the silicon and aluminum oxides forming clay. Clay is found where it was formed, or it can be carried by rivers and deposited elsewhere. When transported by water the particles continue to be ground finer and finer by other rocks and settling. As a result, clay is a major component of soil all over the world, with a variety of properties according to the precise conditions that applied during its formation. The important mineral in pottery is kaolinite, which is made up of silicon and aluminum oxides. Glaze: is essentially a thin coating of glass over a fired ceramic object. Glaze is used for aesthetic and practical reasons because t makes clay waterproof or “food safe”. The glaze usually has three main components: 1) silicon dioxide to provide the main body, 2) aluminum oxide to enhance the viscosity of the glaze by crosslinking the silica networks, 3) fluxes, generally alkali or alkaline earth metal oxides, to lower the melting point of the mixture to the temperature of firing. Alumina silicate: is a fibrous material made of aluminum oxide and silicon dioxide. These are glassy solid solutions rather than chemical compounds used in ceramic glaze. The compositions are often described in terms of % weight of alumina and silica. Temperature resistance of the glaze increases as the % alumina increases. Bisqueware: is unglazed, ceramic ware. The related term, biscuit, refers to pottery that has been fired but not yet glazed. The porous nature of biscuit earthenware means that it readily absorbs water. The temperature of biscuit firing is usually at least 1000°C, although higher temperatures are common. The firing of the ware that results in the biscuit article causes permanent chemical and physical changes to occur. These result in a much harder and more resilient articles which can still be porous, and this can ease the application of glazes. Ceramic Change: the slow process of clay becoming ceramic. Clay which is exposed to temperatures of 600oC / 1112oF, loses its chemically bound water molecules and can no longer be broken down by water. Once this change has occurred it cannot be reversed. Deflocculate: to disperse the particles in a slip so that less water is required to make the slip fluid. Eutectic: means “of greatest fusibility.” In chemistry this is said of an alloy or mixture whose melting point is lower than that of any other alloy or mixture of the same ingredients. In ceramics, this refers to a mixture of two substances in clays or glazes that creates the lowest melting point in the whole series of possible compositions. Firing: heating ceramic clays and glazes to their maturity point, creating a permanent object. Feldspar: One of the predominant naturally occurring fluxes used primarily in stoneware glazes. The three most commonly used feldspars are Potash feldspars, Soda Feldspars, and Lithium Feldspar. Flocculate: In chemistry, flocculate refers to the process by which fine particulates are caused to clump together into a “floc” (think birds). The floc may then float to the top of the liquid (creaming), settle to the bottom of the liquid (sedimentation), or be readily filtered from the liquid. In ceramics, this process refers to thickening and mixing of glazes and slips.
Flux: The word flux means the action or process of flowing or flowing out. A flux is a substance, which causes or promotes melting. In ceramics, a ceramic flux promotes partial liquification in clay and glazes. Fluxes are used in glazes to lower the high melting point of the glass formers silica and boric trioxide. The most commonly used flux in glazes contain lead, sodium, potassium, lithium, calcium, magnesium, barium, zinc, strontium, and manganese. In clay, a flux creates a limited and controlled amount of glass, which works to cement crystalline components together and reduces the melting point. The most common fluxes used in clay potassium oxide and sodium oxide which are found in feldspars. Frit: A combination of materials that have been melted into a glass, cooled, and reground into a powder prior to being added to a glaze recipe. Fuse: To melt and bind together. Iron Oxide: is a common colorant in ceramics. When combined with the right glaze and firing iron oxide can produce greens, browns, blacks, yellows, oranges, subtle blues and grays. The best colors in iron glazes happen in a reduction firing. Kaolin: primary clay in its purest form. Maturing Point: The time and temperature needed to completely fire a glazed or clay object. The maturing point is the point at which the ceramic ware becomes a permanent object. Oxide: Any element combined with oxygen. Oxidation: A firing where there is either no combustion occurring, such as in an electric kiln, or where there is sufficient oxygen in the kiln to allow the fuel to burn cleanly. The atmosphere of the kiln (oxidation or reduction) dramatically affects the resulting clay and glaze colors, for example; copper in oxidation is green (as in copper oxide) in reduction it becomes red (more like the metal copper).
CERAMICS Permanence: the state or quality of lasting or remaining unchanged indefinitely. In ceramics, this is the opposite of plasticity: it means the clay material no longer has plasticity. Plasticity: the quality of a material that makes it easily shaped or molded. In physics and materials science, plasticity describes the deformation of a material undergoing changes of shape in response to applied forces. In ceramics, this refers to the quality of clay which allows it to be manipulated, shaped and molded without cracking or crumbling. The plastic properties of clay are principally determined by the size of the platelets. The smaller the platelets the more plastic the clay is. Porosity: a measure of the empty (i.e., “void”) spaces in a material. It is a fraction of the volume of these empty spaces, or “voids”, over the total volume. The measure is read as a number between 0 and 1, or as a percentage between 0 and 100%. There are many ways to test porosity in a substance or part, such as industrial CT scanning. The term porosity is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, earth sciences, soil mechanics and engineering. Reduction: a situation where too much fuel is introduced into the kiln to be able to burn with the available oxygen, consequently oxygen is ‘stolen’ from the pots in the kiln, it affects the clay and the glaze color. For example, even a tiny amount of iron present in porcelain changes it hue from a creamy color in oxidation to a slight gray blue in reduction. Refractory: resistant to heat. Shrinkage: the proportionate decrease in dimensions or volume of a material, usually as a result of a change in temperature. This term can apply to many materials, such as metal, concrete or wood, and is used in fields such as engineering and materials science. In ceramics shrinkage refers to the decrease in the size of a clay object due to drying and firing. Dry shrinkage is reversible with the return of water, but firing shrinkage is permanent due to chemical and physical changes clay undergoes when exposed to heat. Silica: is the primary glass-forming oxide used in pottery. A glass-forming oxide must be present for a glaze to work because as silica’s melting point is 1800oC, 3272 oF, so a flux is always present to reduce the melting point to a workable range. Soluble: means capable of being dissolved in water. The solubility of a substance fundamentally depends on the properties of the solute and solvent as well as the temperature, pressure and the pH of the solution. In ceramics, this term is used most often in reference to mixing slips and glazes. Thermal Shock: thermal shock occurs when a change in temperature change causes different parts of an object to expand by different amounts. This uneven expansion - differential expansion – causes points of stress or of strain. When this stress exceeds the strength of the material, cracks form. In ceramics this refers to breakage of a ceramic piece caused by sudden temperature changes. Vitrify: means to convert (something) into glass or a glasslike substance, typically by exposure to heat. In ceramics, this is the processes that happens with glazed ceramicware in the kiln. Viscosity: the ability of a liquid to flow, the term is used in ceramics in relation to molten glazes, glaze suspensions, and slips. A stiff molten (liquid) glaze is one of high viscosity, while a runny molten (liquid) glaze is one of low viscosity.
CERAMICS
DIGITAL MEDIA
Digital Media Aggregator: a web site where headlines and other content are collected for easy viewing, like Yahoo News. Avatar: a two or three-dimensional icon that represents a computer user or gamer. Blog: a web page usually updated by one person; most allow viewers to post comments Digital footprint: all information that can be found online about a person; posted by the person or others, on purpose or accidentally. Digital media: computers, cell phones, digital video, social networking sites, that allow users to create, communicate and interact with each other. Digital native: a person in whose life there have always been computers, video games and the Internet. Fauxtography: misleading images that are changed, modified or manipulated to trick the viewer. Flaming: the act of making mean comments online; usually in all CAPITAL LETTERS, and often with intent to hurt.
DRAWING
Social network: a web site, like Facebook, that connects people and allows them to share information. Tag (or Hashtag): a short label that can be attached to a blog, a photo, or other content to be easily found by those searching for it. Text message: also known as SMS; a fewer than 160 character message sent from a cell phone. Troll: someone who posts unwanted ads (spam) on online message boards. Virtual world: a computer environment where users are themselves or avatars and interact in real time with other users. Wiki: a web site that can be changed and edited by anyone who has access to it; subject can be any interest or community. MMS: a text message that contains an attached multimedia file such as a song, image or video.
Drawing
Flame wars: when two or more people participate in mean, hurtful comments back and forth.
Vectors: an object that has both a magnitude and a direction. In geometery, a vector is a line with a direction, starting at a point and ending with an arrow indicating the direction. The direction of the vector is determined from its tail, or starting point, to its head.
Mash-up: a remix or blend of songs, videos, or other media into one product.
Euclidian Geometry: a form of math that was the first system to define space as points, lines and planes.
MMOG: a massive multiplayer online game; an online virtual world that many players play in together.
Parallel: parallel lines are lines in a plane which do not meet, intersect or touch at any point. By extension, a line and a plane, or two planes, in three-dimensional space that do not share a point are also said to be parallel.
P2P: (peer-to-peer) a network, like Skype, that allows for sharing of information directly between two computers. Persistent: lasting a long time, sometimes forever; information that a person posts online that does not go away.
Isometric: in an isometry, the distance between any two points in a figure is the same as the distance between their corresponding images in the transformed image.
Phishing:the illegal act of sending messages that appear to come from real sources, but really come from spammers to get people to share personal information.
Reflection: transformation in which a geometric figure is reflected across a line, creating a mirror image. That line is called the axis of reflection.
Pitfall: a trap or unnoticeable danger; using the Internet can lead to these if not used wisely.
Rotation: a motion of a shape around a fixed point.
Podcast: a downloadable digital video or audio file; can be narrated or contain music and video.
Translation: is a transformation of a plane that slides every point of a figure the same distance in the same direction.
DRAWING Two dimensional: a shape that only has width and height, and no thickness. Squares, Circles, Triangles, etc are two dimensional objects Three-dimensional: an object that has height, width and depth, like any object in the real world. The human body is three-dimensional. One point perspective: exists when the scene is composed entirely of linear elements that intersect only at right angles. If one axis is parallel with the picture plane, then all elements are either parallel to the painting plate (either horizontally or vertically) or perpendicular to it. All elements that are parallel to the painting plate are drawn as parallel lines. All elements that are perpendicular to the painting plate converge at a single point (a vanishing point) on the horizon. One vanishing point is typically used for roads, railroad tracks, or buildings viewed so that the front is directly facing the viewer. Any objects that are made up of lines either directly parallel with the viewer’s line of sight (like railroad tracks) or directly perpendicular (the railroad slats) can be represented with one-point perspective. Da Vinci’s The Last Supper is an excellent example of one point perspective. Two point perspective: can be used to draw the same objects as one-point perspective, rotated, such as looking at the corner of a house, or looking at two forked roads shrink into the distance. One point represents one set of parallel lines, the other point represents the other. Looking at a house from the corner, one wall would recede towards one vanishing point, the other wall would recede towards the opposite vanishing point. Linear perspective: a mathematical system for creating the illusion of space and distance on a flat surface that turns drawing into an exercise in geometry. The system originated in Florence, Italy in the early 1400s. The fundamental idea of linear perspective is to treat the painted picture as a window, and trace sight lines from the viewers eye through the window and onto the scene. Three-point perspective: usually used for buildings seen from above (or below). In addition to the two vanishing points from before, one for each wall, there is now one for how those walls recede into the ground. This third vanishing point will be below the ground, and is known as a nadir, the vanishing point for vertical lines in the down direction. Looking up at a tall building is another common example of the third vanishing point. This time the third vanishing point is high in space, and is known as a zenith: the vanishing point for vertical lines in the up direction. Golden ratio: also known as the divine proportion, golden mean, or golden section, Golden ratio is a number often encountered when taking the ratios of distances in simple geometric figures such as the pentagon, pentagram, decagon and dodecahedron. The Golden ratio is found by dividing a line into two parts so that the longer part divided by the smaller part is also equal to the whole length divided by the longer part. It is exactly equal to (1+√5)/2, and is approximately equal to 1.618. The Greek letter “phi” is often used as a symbol to represent the golden ratio.
JEWELRY & METALSMITHING Foreshortening: the visual effect or optical illusion that causes an object or distance to appear shorter than it actually is because it is angled toward the viewer. Additionally, an object is often not scaled evenly: a circle often appears as an ellipse and a square can appear as a trapezoid.
Jewelry & Metalsmithing Acid: a chemical substance that neutralizes alkalis, dissolves some metals, and turns litmus red; typically, a corrosive tasting liquid. On a molecular level, a substance is an acid when it produces hydrogen ion h+1 in a water solution. Alloy: a material composed of two or more metals or a metal and a nonmetal. Alloys are used in some applications, where their properties are superior to a pure element. Examples of alloys are steel, solder, brass, and pewter. Annealing: in metallurgy and materials science, is a heat treatment that alters the physical and sometimes chemical properties of a material to soften and prepare it for further work, such as shaping, stamping, or forming. It involves heating a material to above its glass transition temperature, maintaining the temperature, and then cooling. Annealing can induce ductility, soften material, relieve internal stresses, and refine the structure by making it homogeneous. In the cases of copper, steel, silver, and brass, this process is performed by heating the material (generally until glowing) for a while and then slowly letting it cool to room temperature in still air. Copper, silver and brass can be cooled slowly in air, or quickly by quenching in water, unlike metals containing iron, such as steel, which must be cooled slowly to anneal. Anodizing: an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant finish. It is an electrolytic process used to increase the thickness of the natural oxide layer on the surface of metal parts. The process is called anodizing because the part to be treated forms the anode electrode of an electrical circuit. Aluminum is well suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized. Brass: is an alloy made of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. It is used for decoration for its bright gold-like appearance; for applications where low friction is required such as locks, gears, bearings, doorknobs, ammunition casings and valves; for plumbing and electrical applications; and extensively in brass musical instruments such as horns and bells where a combination of high workability (historically with hand tools) and durability is desired. Bronze: an alloy of copper, tin, zinc, phosphorus, and sometimes small amounts of other elements that has long been used in art for casting, engraving, and forging. Bronzes are harder than brasses and are produced by melting the copper and adding tin, zinc, and other substances. Bronze is used for coins, medals, steam fittings, and gunmetal and was formerly used to make cannons. Because of its particularly sonorous quality, bell metal, containing from 20% to 24% tin, is used for casting bells and other musical instruments. Casting: is a process by which a liquid material is poured into a mold, which contains a hollow cavity of a desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is broken out of the mold to complete the process. Casting materials are usually metals or various materials that cure after mixing two or more components together; examples are epoxy, concrete, plaster and clay. Casting is most often used for making complex shapes that would be other-
JEWELRY & METALSMITHING
JEWELRY & METALSMITHING of printed circuit boards and semiconductor devices on glass, and in the preparation of metallic specimens for microscopic observation. Ferrous: a term that means “containing or consisting of iron”. Ferric Chloride: a commonly used acid to etch zinc and copper. Ferric chloride is a strongly acidic chemical and gloves, vapour mask and good ventilation are required. Firescale: a layer of oxides that forms on the surface of metal when a certain level of heat is applied. Firescale commonly occurs during the soldering process in jewelry manufacture, such as soldering a bale onto a finished pendant. The firescale stain can only be removed with further polishing, or removal of affected metal. Flux: the action or process of flowing or flowing out. In metalsmithing, flux is a material used during the soldering process, that is painted onto the join to absorb oxygen during soldering, keeping the silver clean and preventing it from oxidizing. Forging: is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer or a die. Forging is often classified according to the temperature at which it is performed: cold forging, warm forging, or hot forging. Forged metals parts are widely used in mechanisms and machines wherever a component requires high strength; such forgings usually require further processing (such as machining) to achieve a finished part. Today, forging is a major worldwide industry. Friction: the resistance that one surface or object encounters when moving over another. In metalsmithing, friction is used to decorate, clean or prepare metals for other processes, such as abrasion, sawing, sanding, grating, rasping, and scraping.
wise difficult or uneconomical to make by other methods. Casting is a 6000 year old process. The oldest surviving casting is a copper frog from 3200 BC. Citric acid: a naturally occurring acid that is a solid at room temperature, melts at 153°C;, and decomposes at higher temperatures. It is responsible for the tart taste of various fruits such as lemons, limes, oranges, pineapples, and gooseberries. It can be used in metalsmithing as an organic, low toxicity pickle. Copper: reddish-brown, ductile, malleable metallic element that is an excellent conductor of heat and electricity with the chemical element of atomic number 29. Commonly used in printmaking, its malleability, or softness, is what causes it to lend itself well to the etching process. Ductility: ability of a metal to change shape without breaking or fracturing, with the cohesion between the molecules remaining sufficient to hold them together. In metalsmithing, ductility is important in wire drawing and sheet stamping. The metal must neither break nor be scraped off during these processes. Platinum, steel, copper, and tungsten have high ductility. Ductility is a focus of rheology, the study of how materials deform and flow in response to force. Enamel: an opaque or semitransparent glassy substance applied to surfaces for ornament or protective coating. Etch: to cut, bite, or corrode with an acid; etched areas develop furrows that when charged with ink will give an impression on paper. Etching occurs as a result of chemical surface corrosion, usually conducted in a controlled fashion on a polished surface of a material such a metal or glass. In metalsmithing, etching is the process of using strong acid to cut into the parts of a metal surface to create a decorative design. In modern manufacturing, other chemicals may be used on other types of material. Etching is used in the manufacturing
Iron: is a lustrous, ductile, malleable, silver-gray metal, number 26 on the periodic table. It is known to exist in four distinct forms. The most common is the alpha form, often called ferrite. Iron is attracted by a magnet and is itself easily magnetized. It is a good conductor of heat and electricity. Iron rusts easily in moist air, forming a complex mixture of compounds called ferrous or ferric oxide. Iron is biologically important because it is a component of hemoglobin, a red oxygen-carrying pigment of the red blood cells of vertebrates. Milling: is the machining process of using rotary cutters to remove material from a workpiece. It covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes in industry and machine shops today for machining parts to precise sizes and shapes. Milling can be done with a wide range of machine tools. The original class of machine tools for milling was the milling machine (often called a mill). Nickel silver: a silver-white alloy composed of 52-80% copper, 10-35% zinc, and 5-35% nickel; sometimes also contains lead and tin. It is also known as German silver and nickel brass. Oxidation: any chemical reaction in which a material gives up electrons, such as when the material combines with oxygen. Burning is an example of rapid oxidation; rusting is an example of slow oxidation. Plastic Deformation: the permanent change in shape of a metallic body as the result of forces acting on its surface, such as hammering. Resistance: ability of a material to resist damage, or change, by chemical action. Metalsmithing makes use of a variety of materials’ resistance to each other in order to create metal objects. Silver: metallic chemical element that in its pure form is
JEWELRY & METALSMITHING
PAINTING
nearly white, lustrous, soft, very ductile, malleable, and an excellent conductor of heat and electricity. In many of its properties it resembles copper and gold, the elements above and below it on the periodic table. Sodium bisulphate: commonly used “pickle” or solution used to clean metal and remove oxides and flux from the soldering process, and can be neutralized with baking soda. Solder: an alloy metal used to create a permanent join between two or more pieces of metal using. The solder has a lower melting point than the metal and with the use of flux and heat, it flows to make a join. The different grades of solder are hard, medium, easy, and extra easy, (there is also an extra hard/IT for enameling). Each grade flows at a different temperature, which is determined by the quantity of zinc in it. Solder can be purchased as sheet, strip, or wire. Sulphuric acid: an acid, commonly used as “pickle”, or the solution used to clean metal and remove oxides and flux from the soldering process. It easily absorbs copper and other materials to strip & clean and finish metal. Can be neutralized with baking soda. Work hardened: also known as strain hardening or cold working, is the strengthening of a metal as the result of forces acting on its surface with the use of heat. This strengthening occurs because of dislocation movements and dislocation generation within the crystal structure (molecular structure) of the material.
Painting Carbon: a chemical element with symbol C and atomic number 6. Carbon, in the form of graphite, is the most commonly used pigment to make the color black. Carbon is one of the few elements known since antiquity, and naturally comes in three forms: graphite, diamond and amorphous (gaseous) carbon. It is present in all life forms and is an element that forms the chemical basis of all known life. Iron oxide: iron oxides are chemical compounds composed of iron and oxygen, sometimes called ferrous oxide. In painting, iron oxides are most often used as a pigment for colors in the red and brown family. Graphite: a naturally occurring form of carbon used as a pigment to make the color black. It is used in paint, charcoal, pencils. Gypsum: a soft sulfate mineral composed of calcium sulfate dehydrate. Naturally white in color, it is the main constituent in many forms of plaster and clays as well as in chalk and gesso. It can be used in making fertilizer, tofu and beer. Zinc / Zinc Oxide: a bluish-white, lustrous metallic element, atomic number 30, that is brittle at room temperature but becomes malleable with heating. In the form of zinc oxide, it is commonly used as a white pigment, substituting for the more toxic lead. Commonly found listed in paint as the color “Chinese white”, considered to be the whitest and least toxic white paint on both oil and watercolor. However, it is less opaque, slower to dry, and brittle than lead white, which if used without adding other mediums or colors leads to cracking. Titanium / titanium dioxide: is the naturally occurring oxide of titanium, an element with the chemical symbol T. When used as a pigment, it is called titanium white. Cadmium: a chemical element with the symbol C, it forms a class of pigments in the color family of yellow/orange/ red. Brilliantly colored, with good permanence and tinting power, Cadmium Yellow, Cadmium Orange, and Cadmium
Red are the most familiar cadmium colors. Cadmium yellow is cadmium sulfide (CdS), Cadmium sulfoselenide is a solid solution of CdS and CdS. that forms oranges and reds Pigment Red 108 is obtained. Zinc cadmium sulfide is a greenish, solid solution of CdS and ZnS. Cadmium yellow is sometimes mixed with viridian to give a bright, pale green mixture called cadmium green. Cobalt: is a chemical element with symbol Co that is used to form pigments in the blue color family such as Cerulean Blue, a color which is a mixture of copper and cobaltous oxides forming hues in a range between blue and cyan. Ultramarine: consists primarily of a mineral containing small amounts of sulfur. It occurs in nature as the semi-precious stone lapis lazuli. Ultramarine is the most complex of the mineral pigments, as a complex sulfur-containing sodium, silicon, lapis lazuli and chloride. The blue color is rooted in the atomic structure of the sulfur. Pigment: is a dry insoluble substance, usually pulverized, which when suspended in a liquid vehicle becomes a paint, ink, etc. used to color matter or substance. Carbon, cadmium, cobalt and ultramarine are pigments used in creating paint. Lead carbonate: a white crystalline compound, of lead and carbon, PbCO 3, used as a paint pigment known as Lead White. It is toxic, and insoluble in water and alcohol. There have been claims that it is partly responsible for darkening in paintings over time, reacting with trace amounts of hydrogen sulfide in the air to produce black lead sulfide that sits on the painting surface. Overtime, it has been replaced by the more stable titanium white. Lead white occurs naturally as a mineral known as hydrocerussite. Chromatics: is the science of color. It includes the perception of color by the human eye and brain, the origin of color in materials, color the-
PAINTING
PHOTOGRAPHY
ory in art, and the physics of electromagnetic radiation in the visible range (that is, what we commonly refer to simply as light).
are absorbed or “subtracted” from white light, so light of another color reaches the eye.
ROY G BIV: is an acronym for the colors of the visible spectrum, or spectral colors: the sequence of hues commonly described as making up a rainbow: Red, Orange, Yellow, Green, Blue, Indigo and Violet. Isaac Newton was the first scientist to divide the visible spectrum into these colors. He chose seven colors out of a belief, derived from ancient Greece, of there being a connection between colors, musical notes, the known objects in the solar system, and the days of the week Visible Spectrum: the visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in the visible spectrum wavelengths is called visible light, or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm. In terms of frequency, this corresponds to a band in the vicinity of 430–790 THz.
Photography
Additive Color: generally referred to as RGB color, is light created by mixing together light of two or more different colors. Red, green, and blue are the additive primary colors normally used in additive color systems such as projectors and computer terminals, often referred to by the acronym RGB. Subtractive color: generally referred to as CMYK color, subtractive coloring uses dyes, inks, and pigments to absorb some wavelengths of light and not others. The color that a surface displays comes from the parts of the visible spectrum that are not absorbed and therefore remain visible. Without pigments or dye, fabric fibers, paint base and paper are usually made of particles that scatter white light (all colors) well in all directions. When a pigment or ink is added, wavelengths
Arts Institute student photo
Emulsion: light sensitive coating on photo paper. The emulsion contains small “grains” called halides (salts). These halides usually are made up of Silver Bromide, Silver Iodide or Silver Chloride. Developer: a chemical solution used to convert the image on film to make it visible. The developer causes the exposed silver halides to reduce to metallic silver when the film is placed in the developing bath. The silver halides that received the most light when the camera shutter was operated reduce to the largest amounts of metallic silver, this is how density is controlled during the exposure of the film. The more “active” a developing agent is the faster it reduces these salts to silver. Some of the more common reducing agents include; Hydroquinone, Metol also known as Elon, Phenidone, and para-phenylenediamine. Fixer: a chemical solution use to remove the silver salts form negatives and prints. After development, many unexposed silver halides are still in the emulsion and are still light sensitive. If we were to turn on the lights immediately after development the unexposed halides would then be exposed to light and since there is still developer in the emulsion they will turn dark and render the image useless. The job of the fixer is to eliminate all of the unexposed silver salts, stop all further development, and often times to shrink or “harden” the swollen emulsion. The most common fixing agent is sodium thiosulfate which dissolves silver bromide, silver chloride and silver iodide.
PHOTOGRAPHY Photosensitive: a material that is chemically of physically changed by light. Silver chloride, bromide, and iodide are photosensitive and used in darkroom photography. Stop bath: a rinse that dilutes the fixer and washes remaining chemicals from the print. Often a low level of acetic acid is added to speed the rinsing process. Stop bath accounts for the characteristic vinegar-like odor of the traditional darkroom.
Printmaking Acid: a chemical that neutralizes alkalis, dissolves some metals, and turns litmus red; typically, a corrosive tasting liquid. On a molecular level, a substance is an acid when it produces hydrogen ion h+1 in a water solution. It is considered the chemical opposite of a base. Base: any substance that produces hydroxide ions, OH-1, in a water solution. It is considered the chemical opposite of an acid. Buffer: a solution containing ions that react with acids or bases to minimize their effect on pH values. Caustic: a substance that is able to burn or corrode organic tissue by chemical action. The acids used in printmaking, and the gases that are produced in the printmaking processes are caustic, so printmakers must take multiple precautions to protect themselves such as wearing breathing masks, gloves and protective eyewear. Copper: reddish-brown, ductile, malleable metallic element that is an excellent conductor of heat and electricity. Commonly used in printmaking, its malleability, or softness, is what causes it to lend itself well to the etching process. The atomic number for Copper is 29. Concentrate: an acid or base that has much more acid or base within the solution than water. Corrosive: means “eating away gradually”. Dilute: a solution containing a relatively small quantity of solute as compared with the amount of solvent. This term is the opposite of “concentrated”. In printmaking, “dilute” refers to an acid bath that contains very little of the acid because it has been weakened by the etching process, which increases the water in the solution. Emulsion: an emulsion is a mixture of two or more liquids that are usually unblendable, usually by agitation or applying heat. In printmaking, it refers to the photosensitive material used in screenprinting that is a mixture of light sensitive material in a viscous medium. Etch: to cut, bite, or corrode with an acid; etched areas develop furrows that when charged with ink will give an impression on paper to create an image. Etching occurs as a result of chemical surface corrosion, usually conducted in a controlled fashion on a polished surface of a material such a metal or glass. In printmaking, etching is traditionally the process of using strong acid to cut into the unprotected parts of a metal surface to create a design in intaglio (relief ) in the metal. In modern manufacturing, other chemicals may be used on other types of material. As a method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today. Etching is also used in the manufacturing of printed circuit boards, on glass, and in the preparation of metallic specimens for microscopic observation. Ferric Chloride: a commonly used acid to etch zinc and copper plates. When used to etch copper plates, the products of the chemical etching processes are a deposit of cupric chloride and a solution of ferrous chloride. Ferric chloride is a strongly acidic chemical so gloves, vapor mask, and good
PRINTMAKING
PRINTMAKING ventilation are required. Etching zinc plates with ferric chloride is also common, but is a more toxic process, as this process gives off bubbles of hydrogen gas which is explosive in air and produces a deposit of iron, which forms a crust over the etched surfaces. The used solution contains zinc chloride which is more toxic and corrosive than ferric chloride. The bubbles of hydrogen require removal with a feather to prevent an uneven bite. Flux: means the action or process of flowing or flowing out. In printmaking this term is used when applying heat to a metal plate that has been coated with powdered resin, called aquatint, so that the powder melts onto the plate. These droplets form a resistant barrier to the acids, which cause the acid to corrode only the uncoated areas of the plate.
PRINTMAKING Solvent: the part of a solution that acts as a dissolving agent. In solutions of solids or gases in a liquid, the liquid is the solvent. In all other solutions (i.e., liquids in liquids or solids in solids) the solvent is the component that is present in larger quantity. The most familiar and widely used solvent is water. Solvents commonly used in printmaking are acetone, alcohol, kerosene and turpentine. Solvents are often organic compounds. They may be divided into polar and nonpolar types. Polar solvents, of which water is an example, have molecules whose electric charges are unequally distributed, leaving one end of each molecule more positive than the other. Nonpolar solvents, of which carbon tetrachloride is an example, have molecules whose electric charges are equally distributed.
Nitric Acid: an acid used most commonly to etch steel. As a highly volatile and corrosive substance, this acid is now used sparingly in print studios, if at all.
Polarity: the property or characteristic that produces unequal physical effects at different points in a body or system, as a magnet or storage battery that determines how a compound reacts with other materials. A molecule can be ionic, polar or non-polar. A polar molecule is formed when one end of a molecule has a positive charge and the opposite end has a negative charge, thus creating electrical poles. A non-polar molecule does not have charges at the ends as the electrons are distributed more symmetrically and cancel each other out. When trying to create a solution, a polar molecule does not mix with a non-polar molecule. An example of this is seen with water, a polar molecule and oil, anon-polar molecule; the two molecules cannot mix to form a solution. However, water and alcohol can mix to form a solution as they are both polar molecules.
Oxidize: to convert an element into an oxide; combine with oxygen often resulting in the production of oxide, or rust. In printmaking, the chemical reaction between copper and ferric chloride is also common, gives off bubbles of hydrogen gas produces a deposit of rust.
Colloid: the definition of a colloid is a combination of molecules mixed through other substances that will not settle out or join with the other substance. In printmaking, screen printing emulsions, hard ground and soft grounds are all colloid solutions.
pH: the presence of hydronium ion relative to hydroxide that determines a solution’s pH. The molecules in pure water dissociate into hydronium and hydroxide ions. If there is an equal number of hydroxide and hydronium ions, it has a neutral pH of 7. A pH value less than 7 indicates an acidic solution, and a pH value more than 7 indicates a basic solution.
Viscosity: the thickness, or a measure of how resistant a liquid is to flowing. The thickness of a semi-fluid liquid such as maple syrup is an example of viscosity. All printmaking inks are viscous. Their viscosity is adjusted to fit the process being used.
Hydronium: when an acid dissolves in water, hydrogen ions combine with water molecules to form Hydronium, H30. It is the amount of Hydronium present in a solution that determines its pH value. Neutralize: a chemical reaction in which an acid and a base react quantitatively with each other to “cancel” each other out. A neutral pH value is 7. In printmaking, baking soda (a base) is often used to neutralize acid baths.
Resistance: ability of a material to resist damage, or change, by chemical action. Printmaking makes use of a variety of materials’ solvency and/or resistance to each other in order to to create images.
Zinc: a bluish-white, lustrous metallic element that is brittle at room temperature but becomes malleable with heating. It is the second most commonly used type of metal in etching, often used in conjunction with the aquatint process. The atomic number for zinc is 30.
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