• Pattern: An approximate duplicate of the final casting used to form the mold cavity.
• Molding material: The material that is packed around the pattern and then the pattern is removed to leave the cavity where the casting material will be poured.
• Flask: The rigid wood or metal frame that holds the molding material.
  • Cope: The top half of the pattern, flask, mold, or core.
  • Drag: The bottom half of the pattern, flask, mold, or core.
• Core: An insert in the mold that produces internal features in the casting, such as holes.
  • Core print: The region added to the pattern, core, or mold used to locate and support the core.
• Mold cavity: The combined open area of the molding material and core, there the metal is poured to produce the casting.
• Riser: An extra void in the mold that fills with molten material to compensate for shrinkage during solidification.
• Gating system: The network of connected channels that deliver the molten material to the mold cavities.
  • Pouring cup or pouring basin: The part of the gating system that receives the molten material from the pouring vessel.
  • Sprue: The pouring cup attaches to the sprue, which is the vertical part of the gating system. The other end of the sprue attaches to the runners.
  • Runners: The horizontal portion of the gating system that connects the sprues to the gates.
  • Gates: The controlled entrances from the runners into the mold cavities.
• Vents: Additional channels that provide an escape for gases generated during the pour.
• Parting line or parting surface: The interface between the cope and drag halves of the mold, flask, or pattern.
• Draft: The taper on the casting or pattern that allow it to be withdrawn from the mold
• Core box: The mold or die used to produce the cores.

Cennino d'Andrea Cennini (c. 1370 – c. 1440) was an Italian painter influenced by Giotto. He was a student of Agnolo Gaddi. Gaddi trained under his father, called Taddeo Gaddi, who trained with Giotto.

Cennini was born in Colle Val d'Elsa, Tuscany.

He is remembered mainly for having authored Il libro dell'arte, often translated as The Craftsman's Handbook. At first thought to be written in the early 15th century, the book is a "how to" on Renaissance art. It contains information on pigments, brushes, panel painting, the art of fresco, and techniques and tricks, including detailed instructions for underdrawing, underpainting and overpainting in egg tempera. Cennini also provides an early, if somewhat crude, discussion of painting in oils. His discussion of oil painting was important for dispelling the myth, propagated by Giorgio Vasari and Karel Van Mander, that oil painting was invented by Jan van Eyck (although Theophilus (Roger of Helmerhausen) clearly gives instructions for oil-based painting in his treatise, On Divers Arts, written in 1125).

The dates of Cennini's life are highly speculative. It is often falsely assumed that he was alive in 1437 because that date appears on one of the copies of his manuscript. This is discussed by Daniel V. Thompson in the preface to his authoritative translation of Il libro dell'arte. Thompson himself does not speculate on Cennini's years of life, a sure indication of the lack of evidence on this point. Thus, dating Cennini's book to the "early 15th century" as above is only a guess. The techniques Cennini describes are grounded in the late 13th and mid 14th centuries. There is no evidence in his writing of the exciting developments in oil painting taking place in the early 15th century. This suggests that his book was indeed written sometime in the 14th century.

Cennini's intention was to provide a practical handbook for the apprentice painter. Along with technical methods, Cennini offered advice on the sort of lifestyle to which a young painter should subscribe. "Your life should be arranged just as if you were studying theology, or philosophy, or other theories, that is to say, eating and drinking moderately, at least twice a day, electing digestible and wholesome dishes, and light wines; saving and sparing your hand, preserving it from such strains as heaving stones, crowbars, and many other things which are bad for your hand, from giving them a chance to weary it. There is another cause which, if you indulge it, can make your hand so unsteady that it will waver more, and flutter far more, than leaves do in the wind, and this is indulging too much in the company of women."

According to Victoria Finlay, in her book Colour: Travels Through The Paintbox, the infamous UK forger Eric Hebborn was greatly influenced by Cennino Cennini. The last book Hebborn wrote before he was brutally murdered was The Art Forger's Handbook. Finlay writes that he "used and adapted Cennino's advice extensively - preparing panels, tinting papers different colours, and making brand new works look as if they had been varnished some time before (by beating egg-white, left overnight and then painted on with a brush), just as the master advised."

For example, alloys which are mixed 14 parts gold to 10 parts alloy create 14-karat gold, 18 parts gold to 6 parts alloy creates 18 karat, and so on. This is often expressed as the result of the ratio, i.e.: 14/24 equals 0.585 and 18/24 is 0.750. There are hundreds of possible alloys and mixtures, but in general the addition of silver will color gold white, and the addition of copper will color it red. A mix of around 50/50 copper and silver gives the range of yellow gold alloys the public is accustomed to seeing in the marketplace. A small amount (0.2%) of zinc can be added to harden the alloy.

The most common grades of gold, in addition to pure 24K, are 22K (92%), 18K (75%), 14K (58%) and 9K (38%).

Colored golds can be classified to three groups:

• the Au-Ag-Cu system, producing white, yellow, green and red golds; typically malleable alloys
• the intermetallic compounds, producing blue and purple golds, as well as other colors. These are typically brittle but can be used as gems and inlays
• the surface oxide layers, such as black gold; mechanical properties depend on the bulk alloy, and the colored surface is prone to wear

White gold is an alloy of gold and at least one white metal, usually nickel, manganese or palladium. Like yellow gold, the purity of white gold is given in karats.

White gold's properties vary depending on the metals and proportions used. As a result, white gold alloys can be used for many different purposes; while a nickel alloy is hard and strong and therefore good for rings and pins, gold-palladium alloys are soft, pliable and good for white gold gemstone settings, sometimes with other metals like copper, silver, and platinum for weight and durability, although this often requires specialized goldsmiths. The term white gold is used very loosely in the industry to describe karat gold alloys with a whitish hue. Many believe that the color of the rhodium plating, which is seen on many commercial pieces, is actually the color of white gold. The term "white" covers a large spectrum of colors that borders or overlaps pale yellow, tinted brown, and even very pale rose. The jewelry industry often hides these off-white colors by rhodium plating.

A common white gold formulation consists of 90 wt.% gold and 10 wt.% nickel. Copper can be added to increase malleability.

The strength of gold-nickel-copper alloys is caused by formation of two phases, a gold-rich Au-Cu, and a nickel-rich Ni-Cu, and the resulting hardening of the material.

The alloys used in jewelry industry are gold-palladium-silver and gold-nickel-copper-zinc. Palladium and nickel act as primary bleaching agents for gold; zinc acts as a secondary bleaching agent to attenuate the color of copper.

About one out of eight people have an allergic reaction to the nickel in some white gold alloys when worn over long periods. A typical reaction is a minor skin rash. Because of this, many European countries do not use nickel white gold. White gold alloys made without nickel are less likely to be allergenic.

Rose gold is a gold and copper alloy widely used for specialized jewelry. It is also known as pink gold and red gold. As it was popular in Russia at the beginning of the nineteenth century, it is also known as Russian gold, although this term has become somewhat rare.

Although the names are often used interchangeably, the difference between red, rose, and pink gold is the copper content – the higher the copper content, the stronger the red coloration. A common alloy for rose gold is 75% gold and 25% copper by mass (18 karat). Since rose gold is an alloy, there is no such thing as "pure rose gold".

A common formulation for red gold is 50% gold and 50% copper.

Up to 15% zinc can be added to copper-rich alloys to change their color to reddish yellow or dark yellow.

The highest karat version of rose gold is also known as crown gold, which is 22 karat. Eighteen karat red gold may be made of 25% copper and 75% gold. For 18 karat rose gold, typically about 4% silver is added to 75% gold and 21% copper to give a rose color. 14 karat red gold is often found in the Middle East and contains 41.67% copper.

Spangold  Some gold-copper-aluminum alloys form a fine surface texture at heat treatment, yielding an interesting spangling effect. At cooling, they undergo a quasi-martensitic transformation from body-centered cubic to body-centered tetragonal phase; the transformation does not depend on the cooling rate. A polished object is heated in hot oil to 150-200 °C for 10 minutes then cooled below 20 °C, forming a sparkly surface covered with tiny facets.

The alloy of 76% gold, 19% copper, and 5% aluminum yields yellow color, the alloy of 76% gold, 18% copper and 6% aluminum is pink.

Green gold alloys are made by leaving the copper out of the alloy mixture and just using gold and silver. It actually appears as a greenish yellow rather than green. Eighteen karat green gold would therefore contain a mix of gold 75% and silver 25% (or 73% gold and 27% silver). Fired enamels adhere better to these alloys.

Green gold was known to Lydians as long ago as 860 BC under the name electrum. Electrum is a naturally occurring alloy of silver and gold.

Cadmium can be added to gold alloys in amount of up to 4% to achieve green color. The alloy of 75% gold, 23% copper, and 2% cadmium yields light green 18ct gold. The alloy of 75% gold, 15% silver, 6% copper, and 4% cadmium yields a dark green alloy. Cadmium is, however, toxic.

Grey gold alloys are made by adding silver, manganese and copper in specific ratios to the gold.

Black gold is a type of gold used in jewelry. Black colored gold can be produced by various methods:

• Electroplating, using black rhodium or ruthenium. Solutions that contain ruthenium give a slightly harder black coating than those that contain rhodium.
• Patination by applying sulfur and oxygen containing compounds.
• Plasma assisted chemical vapor deposition process involving amorphous carbon
• Controlled oxidation of gold containing chromium or cobalt (e.g. 75% gold, 25% cobalt).

A range of colors from brown to black can be achieved on copper-rich alloys by treatment with potassium sulfide.

Cobalt-containing alloys, e.g. 75% gold with 25% cobalt, form a black oxide layer with heat treatment at 700-950 °C. Copper, iron and titanium can be also used for such effect. Gold-cobalt-chromium alloy (75% gold, 15% cobalt, 10% chromium) yields surface oxide that's olive-tinted because of the chromium(III) oxide content, is about 5 times thinner than Au-Co and has significantly better wear resistance. The gold-cobalt alloy consists of a gold-rich (about 94% Au) and cobalt-rich (about 90% Co) phases; the cobalt-rich phase grains are capable of oxide layer formation on their surface.

More recently a laser technique has been developed that renders the surface of metals deep black. A femtosecond laser pulse deforms the surface of the metal forming nanostructures. The immensely increased surface area can absorb virtually all the light that falls on it thus rendering it deep black.

Purple gold (also called amethyst gold and violet gold) is an alloy of gold and aluminum rich in gold-aluminium intermetallic (AuAl₂). Gold content in AuAl₂ is around 79% and can therefore be referred to as 18 karat gold. Purple gold is more brittle than other gold alloys, as it is an intermetallic compound instead of a malleable alloy, and a sharp blow may cause it to shatter. It is therefore usually machined and faceted to be used as a "gem" in conventional jewelry rather than by itself. At lower content of gold, the material is composed of the intermetallic and an aluminium-rich solid solution phase. At higher content of gold, the gold-richer intermetallic AuAl forms; the purple color is preserved to about 15% of aluminium. At 88% of gold the material is composed of AuAl and changes color. (The actual composition of AuAl₂ is closer to Al₁₁Au₆ as the sublattice is incompletely occupied.)

Blue gold is an alloy of gold and indium. It contains 46% gold (about 12 ct) and 54% indium, forming an intermetallic compound AuIn₂, with a clear blue color. With gallium, gold forms an intermetallic AuGa₂ (58.5% Au, 14ct) which has slight bluish hue. The melting point of AuIn₂ is 541 °C, for AuGa₂ it is 492 °C. AuIn₂ is less brittle than AuGa₂, which itself is less brittle than AuAl₂.

All the AuX₂ intermetallics have crystal structure of CaF₂ and therefore are brittle. Deviation from the stoichiometry results in loss of color. Slightly nonstoichiometric compositions are however used, to achieve a fine-grained two- or three-phase microstructure with reduced brittleness. A small amount of palladium, copper or silver can be added to achieve a less brittle microstructure.

The intermetallic compounds tend to have poor corrosion resistance. The less noble elements are leached to the environment, and a gold-rich surface layer is formed. Direct contact of blue and purple gold elements with skin should be avoided as exposition to sweat may result in metal leaching and discoloration of the metal surface.

A surface plating of blue gold on karat gold or sterling silver can be achieved by a gold plating of the surface, followed by indium plating, with layer thickness matching the 1:2 atomic ratio. A heat treatment then causes interdiffusion of the metals and formation of the required intermetallic compound.

Blue gold can be achieved by formation of an oxide layer on an alloy of 75% gold, 24.4% iron, and 0.6% nickel; the layer forms on heat treatment in air between 450–600 °C.

Gold of purity 20–23 carat, when alloyed with ruthenium, rhodium and three other elements and heat-treated at 1800 °C, forms a 3–6 micrometers thick surface layer with a rich sapphire blue color.

Copper  is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.

The metal and its alloys have been used for thousands of years. In the Roman era, copper was principally mined on Cyprus, hence the origin of the name of the metal as сyprium (metal of Cyprus), later shortened to сuprum. Its compounds are commonly encountered as copper(II) salts, which often impart blue or green colors to minerals such as turquoise and have been widely used historically as pigments. Architectural structures built with copper corrode to give green verdigris. Decorative art prominently features copper, both by itself and as part of pigments.

Denatured alcohol (or methylated spirits) is ethanol that has additives to make it more poisonous or unpalatable, and thus, undrinkable. In some cases it is also dyed.

Denatured alcohol is used as a solvent and as fuel for spirit burners and camping stoves. Because of the diversity of industrial uses for denatured alcohol, hundreds of additives and denaturing methods have been used. Traditionally, the main additive is 10% methanol, giving rise to the term 'methylated spirit'. Other typical additives include isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, and denatonium. Denaturing alcohol does not chemically alter the ethanol molecule. Rather, the ethanol is mixed with other chemicals to form an undrinkable mixture. Different additives are used to make it difficult to use distillation or other simple processes to reverse the denaturation. Methanol is commonly used both because of its boiling point being close to that of ethanol and because it is toxic. In many countries, it is also required that denatured alcohol be dyed blue or purple with an aniline dye.

As a sanding aid, as the alcohol helps to more easily remove excess dust because it does not open the wood grain the way that water does. As a solvent in shellac and shellac-based products.

Ductility

Dutch metal

Dutch metal is a form of brass being an alloy of copper, 84% and zinc 16%. It is very malleable and ductile and can be beaten into very thin sheets. It is these sheets that are sold as Dutch Metal, for use as metal leaf or imitation gold leaf. The addition of arsenic produces an alloy with similar properties but coloured white.

Enamel paint is paint that air dries to a hard, usually glossy, finish, used for coating surfaces that are outdoors or otherwise subject to hard wear or variations in temperature; it should not be confused with decorated objects in "painted enamel", where vitreous enamel is applied with brushes and fired in a kiln. The name is something of a misnomer as in reality, most commercially-available enamel paints are significantly softer than either vitreous enamel or stoved synthetic resins, and are totally different in composition; vitreous enamel is applied as a powder of paste and then fired at high temperature. There is no generally accepted definition or standard for use of the term enamel paint, and not all enamel-type paints may use it.

Typically the term "enamel paint" is used to describe oil-based covering products, usually with a significant amount of gloss in them, however recently many latex or water-based paints have adopted the term as well. The term today means "hard surfaced paint" and usually is in reference to paint brands of higher quality, floor coatings of a high gloss finish, or spray paints. Some enamel paints have been made by adding varnish to oil-based paint.

• Floor enamel – May be used for concrete, stairs, basements, porches, and patios.
• Fast dry enamel – Can dry within 10–15 minutes of application. Ideal for refrigerators, counters, and other industrial finishes.
• High-temp enamel – May be used for engines, brakes, exhaust, and BBQs.
• Enamel paint is also used on wood to make it resistant to the elements via the waterproofing and rot-proofing properties of enamel. Generally, treated surfaces last much much longer and are much more resistant to wear than untreated surfaces.
• Model building - This paint is usually sold in 14 ml tinlets.

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a powerful psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a solvent, and as a fuel. In common usage, it is often referred to simply as alcohol or spirits.

"Gesso", also known "glue gesso" or "Italian gesso" is a traditional mix of an animal glue binder, usually rabbit-skin glue, chalk, and white pigment, used to coat rigid surfaces such as wooden painting panels as an absorbent primer coat substrate for painting. Its absorbency makes it work with all painting media including water-based media, different types of tempera, and oil paint. It is also used as a base on three-dimensional surfaces for the application of paint or gold leaf. Mixing and applying it is an art form in itself since it is usually applied extremely thin in 10 layers or more. It is a permanent and brilliant white substrate, used on wood, masonite and other surfaces. The standard hide glue mixture is rather brittle and susceptible to cracking, thus making it suitable for rigid surfaces only. For priming flexible canvas, a emulsion of gesso and linseed oil, also called a "half-chalk ground", is used. In Geology, Italian "Gesso" corresponds to the English "Gypsum", as it is a calcium sulphate compound (CaSO₄·2H₂O).

Modern "acrylic gesso" is technically not gesso at all. It is a combination of calcium carbonate with an acrylic polymer medium latex, a pigment and other chemicals that ensure flexibility, and ensure long archival life. It is sold premixed for both sizing and priming a canvas for painting. While it does contain calcium carbonate (CaCO3) to increase the absorbency of the primer coat, Titanium dioxide or titanium white is often added as the whitening agent. This allows the "gesso" to remain flexible enough to use on canvas. High concentrations of calcium carbonate, or substandard latex components will cause the resulting film to dry to a brittle surface susceptible to cracking.

Acrylic gesso can be colored, either commercially by replacing the titanium white with another pigment, such as carbon black, or by the artist directly, with the addition of an acrylic paint. Acrylic gesso can be odorous, due to the presence of ammonia and/or formaldehyde which are added in small amounts as preservatives against spoilage. Pre-gessoed canvases can be obtained commercially.

Acrylic gesso is a modern art material, and is used as a primer for oil painting and acrylics. Many of the solvents used in oil painting, such as turpentine or odorless mineral spirits (OMS), will leach some oil through a thin acrylic primer coat and damage the canvas underneath just as traditional hide glue sizing did. However, sufficient coverage and penetration of an absorbent support is archivally acceptable.

Although it is generally believed to be acceptable, several painting texts such as The Painter's Handbook state that it is unwise to paint in oils over acrylic gesso because, unlike with time-tested alternatives such as rabbit skin glue, the oil paint will eventually delaminate from the acrylic gesso surface. This effect may not make itself manifest for several decades. The cause for this problem is the inability of oil paint to establish both physical and chemical bonds with the acrylic base. Applied to a canvas that has been primed with rabbit-skin glue, oil paint is able to penetrate the ground (which is porous, unlike acrylic gesso) and establish a permanent bond, both chemical and physical. Manufacturers of commercially sold, pre-gessoed canvases deny that delamination takes place. However, curators in the Smithsonian Museum are not permitted to use acrylic gesso under oil paint, precisely because of the delamination problem.

Soy-based gesso is a low emitting bio-based gesso made from recycled soy content. Soy gesso is made with new bio-based dispersion technology that uses a soy ester with a modified soy-vegetable oil acrylic. The surface is similar to acrylic gesso, but is not a solid acrylic. Soy gesso is made using a thin film of a modified acrylic and the soy ester. The penetration and adhesion of the soy ester to the substrate and the thin film of modified acrylic may have advantages in creating a surface that allows a physical bond between the gesso and the oil paint. In addition, the thinner modified acrylic film is less resistant to cracking than a solid acrylic gesso.

Gesso is also used by sculptors to prepare the shape of the final sculpture (fused bronze) or directly as a material for sculpting. Gesso can also be used as a layer between sculptured wood and gold leaf. In this case, a layer of red shellac called "assiette" is used to cover the Gesso before applying the gold. A collection of gesso sculptures is properly called a gypsotheque.

Gilding metal is a copper alloy, comprising 95% copper and 5% zinc. Technically, it is a brass. Gilding metal is used for various purposes, including the jackets of bullets, driving bands on some artillery shells, as well as enameled badges and other jewellery.