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lossary of Terms

lossary of Terms


This is a Glossary of Terms that David is preparing for use with a basic enameling course.


An organic holding agent made from sea products.
The process of uniting or causing to adhere, as with glue.
The process of gently heating metal that has become work-hardened in order to restore its malleability.
Placing enamel over a textured metal surface, which traditionally would be textured by engraving or chiseling the metal surface.
See Bas-relief.
The process of polishing metal with a hard-surfaced tool, traditionally polished steel or agate.
Ceramic Pigments
These earth pigments will stain the enamel, i.e., color it.  It is necessary to apply another layer of flux or translucent enamel on top of it in order to secure it.
Removing metal from an object so that cells that can hold enamel are made, then enameling in those cells.  Similar to Cloisonné, except the cells are made by removing metal from the object instead of adding wires on top of it.
The technique of punching metal with tools to incise designs into the metal surface.
Creating cells on an object with wire, then enameling in those cells. Similar to Champlevé, except the cells are made by adding wire to the object instead of by removing metal from it.
Coefficient of Expansion
A Coefficient of Expansion is a numeric rating that expresses the percentage of the expansion of the enamel in relation to the temperature.  The higher the number, the more the enamel expands.  If two enamels (or an enamel and it's metal substrate) have coefficients that are too different, they will be incompatible.
Copper Oxide
The black layer that forms on copper when heated.  Also called cupric oxide or calamina.
Counter Enamel
Enamel and metal both expand and contract as they change temperatures.  They do not necessarily expand at the same rate.  Enamel on one side of a piece can cause the piece to warp.  While the enamel is still hot enough to be malleable, this can warp the metal, otherwise it can cause the enamel to fall off.  Counter enamel is enamel placed on the "back side" of the piece to equalize that force.
Depletion Gilding
The process of bringing silver to the surface of sterling silver (by removing copper oxides) from the surface of the metal.
Émail Peint
See Painted Enamel.
Enamel Relief
See Ronde bosse.
Cutting away the surface of a metal object with gravers, a type of chisel.  Gravers can cut grooves or remove an entire, flat layer from a portion of the object's surface.
A liquid similar to an oil, but made from a mixture of hydrocarbons and plant extractions.  They are very volatile and are used as an agglutinate for vitreous paint, liquid gold or silver, and for Limoges white.
The process of removing selected portions of a metal object's surface by the use of an acid.  The areas that are not intended for removal by the acid are covered with a substance that will resist the acid's corrosive effects.  Such a substance is called a Resist.
Fire Scale
The brownish-red oxide that forms on heated copper.
Firing is the process of combining time and temperature.  It is not suffcient to bring enamel to a specific temperature, it is important to do so for a sufficient length of time.  Any one firing will typically run from 1 to 5 minutes, depending upon the size of the work, the hardness and thickness of the enamel, the type and thickness of the metal, the size of the kiln compared to the piece, etc.
A clear enamel used as an under (or over) coat for other enamels, or as a filler.
Extremely thin metal sheets.  In an enameling context, they are embedded between layers of enamel (with translucent colors on top of it).
See Fusion Point.
Fusion Point
The point at which a solid will suddenly change to a liquid state at a given temperature.  Unlike metals, enamel (like all glass) does not suddenly flow.  Glass is technically a solid liquid that moves very, very slowly.  (That is why old window panes are thicker at the bottom.)  When glass is heated, it just flows more quickly.
This technique uses a single translucent light color on a dark background.  As one applies additional layers of the light color, one gets a shaded, relief effect.
The hardness rating of enamels lists a broad temperature range at which the enamel will melt.  Modern enamels are rated as being soft, medium or hard.  Soft enamels melt in the 1200 to 1290 ˚F range, medium enamels melt in the 1380 to 1560 ˚F range, and hard enamels melt in the 1560 to 1740 ˚F range.
Holding Agent
A holding agent fixes the enamel grains in place until the firing process is completed.  It is burned away during firing.
Structurally, cooled enamel is an isotropic material.  It's physical properties are constant in all directions, unlike some crystalline structures.  This allows enamel to form walls.
Lily Root
An agglutinate that is used to hold cloisons onto non-horizontal surfaces.
Limoges White
Liquid Enamel
Enamel suspended in water and formulated so it can be applied by painting, spraying, dipping or pouring onto the piece.  Ceramic pigments can also be mixed into the liquid enamel.
Melting Point
The point in time when the enamel is completely melted and free flowing.
Metallic Lusters
Fine particles of gold or palladium that are suspended in an organic medium (that burns off during firing), leaving a metallic sheen to the finish.
A small piece, very detailed, using vitreous paint on a smooth, fired opaque enamel support.
An opaque enamel has a solid color that cannot be seen through.
An opalescent enamel has a visual sheen similar to that found on opals.
Orange Peel
As enamel grains start to melt, they flow together.  Enamel that is almost, but not quite done, takes on a texture similar to that of an orange peel.
Pigment mixed with flux. The pigment does not become glass until fired with the flux.
Painted Enamel
Applying enamels in a similar manner to that of paint.
Painting on Enamel
The technique of producing painted enamel.
Enamels, though one can approximate the appearance of a painting, are not paints. Not all enamels are compatible with one another. Palettes are used to test (and later document for re-use) how different combinations of enamels respond to one another.
Particle Size
Enamel grains can be purchased in standard size ranges.  They are separated into size bands using mesh screens using progressively finer meshes.  Typical modern ranges are 100, 200 and 325 mesh.
The process of removing oxides and oils from the metal using corrosive chemicals. This is done before enamel or flux is applied (and when the enameling is done and the piece is to be cleaned and polished).
A plank-like support for enameled pieces in and out of the kiln, typically made out of ceramic.
This technique is similar to Cloisonné in that the enamel is applied within cells made out of wire applied to the metal. However, the cells have no backing so the enamel within them is visible from both sides of the piece.
The fired piece is removed from the kiln and placed into a sealed metal container filled with combustible material.  This produces an oxygen-reduced atmosphere which can affect the color of the enamel.
Relief Enamel
See Ronde Bosse.
Ronde Bosse
Enamel affixed to a three dimensional object that has high relief embossing or repoussé designs on it.
Scratching through a layer of unfired enamel to reveal the metal or enamel underneath it.
Softening Point
The point in time at which the viscosity of the enamel is overcome and the enamel starts to become fluid and adhere to the metal.
Removing enamel from the piece by using abrasives, typically fine stones. Stoning is done when the piece is wet.
Sugar Firing
Purposely under-firing the topmost enamel layer to produce a gritty texture in the enamel.
Tool & Die
A translucent enamel, though not clear, can be seen through if it is not too thick. This allows the metal (or air) behind the enamel to be seen as part of the design.
A metal or ceramic support that is used to hold the piece to be enameled. It is shaped so that it (mostly) touches the sides of the piece and not the top or bottom surface.
This is the resistance of a fluid to flowing freely.  As enamel heats up over time, it flows more freely.
A material that will melt and then become glassy.
Vitreous Paint
Paint that melts and then becomes glossy.
Watercolor Enamel
Ground enamel suspended in water so that can be painted on.
The process of applying enamel grains that are wet, as opposed to dry.


Most of the above definitions were adapted from the following excellent sources:


  1. Grains of Glass
  2. López-Ribalta, Núria and i Miró, Eva Pascual. Enameling on Metal: The Art and Craft of Enameling on Metal Explained Clearly and Precisely. Barron's, 2010.