Here's another entry from Dick Johnson's Encyclopedia of Coin and Medal Terminology.
Preparing the three-dimension relief of a new coin or medal design in some permanent form, usually of hard substance as plaster of Paris. The artist or modeler may first work in a more pliable substance – as clay, plastecine or wax – then cast this in plaster. Or the modeler may work in plaster alone. The coin or medal design is modeled oversize, from three to nine times or more the size of the intended piece. The final model must be a somewhat permanent substance to pass along to the mint or medalmaker: plaster is ideal for this.
After the artist is satisfied his model is complete and perfect it is submitted to the mint or medalmaker. Once the design and relief is approved, they will process it by making an even more substantial copy in harder material: copper by electroforming or epoxy by casting. This pattern, then, will be mounted on a die-engraving pantograph to reduce and cut a die to the required size. Virtually no definition of detail is lost in this process. Medal makers say:
If the design is in the model, it is in the medal.
General Modeling Considerations
Modelers, whether preparing a clay or plaster model, can work in the positive or negative. The relief design is formed by adding to the positive, or carving in the negative. The modeler can go back and forth from positive to negative at will (since it changes with each casting) by repeated plaster casting. Clay can be added to a plaster model to build up relief at any stage of this modeling, or the plaster can be carved away (also creating relief in the negative model), to form the design. Plaster of Paris is ideal since it can be easily formed, cast, modified and touched up at any time.
Lighting is very important to a modeler, working is best done near a northern window. Since the relief will be viewed as reflected light and shadows, the modeler will often tilt his model or change a light source to view his relief. (Light from the top of the model – as if it were sunlight –is most useful, particularly if the model bears a human portrait.)
At all stages the modeler must keep in mind special requirements for coin and medal modeling: (1) the interspacial relationships of all elements,( 2) no undercuts (absolutely prohibited if the item is to be diestruck),(3) a bevel on all relief (so the ultimate die can retract from the struck piece), (4) the height of the relief, (5) the state of the surface of the media, 6) elimination of possible congruent mass with the design on the opposite side, 7) do not model a crevice deeper than its width, and 8) the creation of as artistic a design as possible appealing to the greatest number of viewers with varying artistic sensibilities. The task is certainly a challenge.
It is useful if the modeler is familiar with the techniques that will be used to make a die from his model. The sculptor should not model a crevice, for example, that a tracing point cannot enter; this is the reason not to form a crevice that is deeper than its width. The artist should study the mechanics of the reduction process (see entry pantograph) and observe this machine in action if possible.
The work order or commission the modeler receives should spell out the height of relief (particularly for the type of press for striking), if the item will have proof surface or the type of finish, and this accompanied by the approved drawing of the design (if the modeler was not the original designer).
How coin and medal modeling is done.
Once a sketch of a proposed coin or medal design is approved, the next step is to prepare this in a three-dimensional bas-relief form. The preparation is much like that of a sculptor molding a statue by adding clay a little at a time to form the model. Unlike sculpture in-the-round, however, an armature or core support is not necessary. Instead the relief design is created on a smooth flat surface or platform, called a background plate (or one that is slightly dished or domed, called a basin).
The modeler then works in his chosen media – clay, plastecine, paraffin, wax. Or the modeler can carve the relief in plaster of Paris.
Background plate. The base for the background plate, usually wood, must be quite sturdy and be four or five inches larger than the intended model. It does not have to be round, even if the modeler is preparing a round model. The two models, for obverse and reverse, should be the same diameter. But the size of the model is not that critical (since it will be mechanically reduced) but ideally should be a size that will fit the pantograph. (But even that is not necessary, should the artist want to work in extreme oversize – an intermediate reduction can be made – and even though this is extra cost, it is sometimes required for coin models.) After all is said, the model and the background plate should be a size the artist is comfortable with.
There is one exception to this, for models to be prepared for a series where the size must be uniform for all items in the series. Then standard background plates are prepared and furnished to the modeler. One master background plate is prepared and plaster casts are made of this and furnished to the modeler for each side. The modeler then prepares his designs on these standard background plates knowing they will be uniform with all others, irrespective of the number he creates, or other artists create.
Size of model. To produce a ½-inch diameter coin – the ideal pattern for a single reduction would be 1 ½ to 4 inches (three to eight times the intended die size). This, obviously, is impractical, so coin models are prepared from, say six to nine inches; medal models are larger, ten to eighteen inches. The reason this does not have to be a very prescribed size is because the die-engraving pantograph can cut a die to a very exact size by a prescribed ratio from a model of virtually any size, say, below eighteen inches. (See pantograph for more on this ratio.)
Border. If a border is required for the design this is usually prepared first. By the use of a template and a pivot in the center of the design (for a round model) the template is guided along a field of clay around the pivot, pushing ahead the removed clay and leaving behind a perfect trail of clay to the configuration of the design in the template. Or, the border can be modeled if necessary (or a combination of both). Once the artist has a desirable border the modeler will often cast this completed border in plaster to form a plaster background plate and build his design upon this plaster form. By doing this he does not have to worry about deforming a clay border while preparing the relief inside the border.
Device. The device is the next to be modeled. It is here where the modeler must build up the design in modulated relief, forming the rises and falls of the surface, what will be the surface of the relief in the end product, the coin or medal. He can make the three-dimensional design by molding a large mass of material, or he can build it by repeated adding of little bits of clay (or the media he is working in). These little bits are called pellets. The modeler then works the surface of this with fingers, a wire tool or a boaster to shape the surface and give it the necessary contour and detail.
Often he will modify the relief from the original design sketch as his mind constantly appraises the relief he is forming with his fingers and tools. The sketch is an overall plan, forming the relief is the execution. Changing the surface is quite easy because the media is so pliable. It can be moved, altered, raised, lowered, shaped, textured, smoothed, detailed, whatever comes to his mind. It is here where experience and knowledge of bas-relief is the model maker's best guide.
Adding detail and ornamentation. The character of the surface is most important. As the artist adds the detail in the clay or other media, he sees in his mind how this will look to the viewer of the final coin or medal. He sharpens up the detail (keeping in mind the ratio of reduction – very tiny detail will disappear with great reduction). At this point he may also add ornamentation to add charm to the total work. Usually this movement of surface clay is done with the wire tool, a steady hand and a very perceptive eye.
Lettering. Generally the last to be completed on the model is the lettering. The artist may model each letter and figure, he can form relief lettering by adding letters made of clay to the positive pattern. Or he may use a template, carved in plaster, to form the letters to be placed into position, or, preformed letters may be used (least advisable because they probably lack harmony with the rest of the design, see form letters). Or the artist may carve the letters in reverse on the negative plaster.
Positioning each letter is an indication of the experience of the modeler. An imaginary base line must be maintained, and the letters must not be tilted. The size and shape of the letters, their typestyle, must be harmonious with the design and with each other. The spacing between the letters (normally called letterspacing) is critical. This interletter spatial relationship must be pleasing to the viewer with no obvious gaps between letters (as less space between OC than between MN for example).
Lettering is the most difficult to model. Even seasoned sculptors, who can design and prepare models of high quality, falter with the lettering. Infrequently admitting this shortcoming they ask others for help. This can be a fellow sculptor or the factory artist where the struck pieces will be made. An example is the Roche Jaune National Park Centennial Keystone Medal of 1972. Frank Hagel prepared the models, Joseph Di Lorenzo did the lettering.
Final touchup. The artist refines his design at every step of modeling. But for a final touchup he has one last opportunity to perfect his design. Modeling imperfections (should there be any) are lessened when the pattern is reduced, but these can easily be corrected in the clay or plaster at this stage. Hairlines, perhaps, are deepened. A sharpness is added to the eyes. Folds in clothing is softened. Texture is replicated where necessary. In all, the final touchup is the artist's last occasion to add charm and sharpness of detail to his model.
A final plaster cast is made. This includes a flange around the model of one to two inches (necessary to fasten the model to the pantograph). After the plaster is thoroughly dried it is then submitted to the mint or medalmaker.
Ten Most Important Factors To Consider
In Preparing A New Coin or Medal Model
1) How to be produced – struck or cast?
2) Height of relief?
3) Model size vs. Coin/Medal size?
4) Degree bevel required with no undercuts?
5) Kind of border?
6) Texture on any surface?
7) If struck, will congruent mass be a problem?
8) How wide a flange on final model?
9) Reduce tiny tall projections (champs levée)?
10) Eliminate deep crevices, must be wider than their depth.
Of course, much of such work can be done with software and automation today, but this is how coins and medals were created for hundreds of years - the coins and medals so many of us collect today.
To read the complete entry on the Newman Numismatic Portal, see:
Wayne Homren, Editor
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