Chasing. The technique of working the surface of metal with chasing tools, finishing up and smoothing out the surface of castings, electroforms, galvanos and struck medals by removing small imperfections. It is said the chaser "moves metal around" but it is more than this in that it includes a variety of techniques – almost all handwork and performed at a bench – with a variety of tools, to produce an attractive and desirable metal surface.The chaser's job is two kinds: flat chasing creating in effect a design or relief on the front of a flat metal surface, as a cisele item; and finish chasing, a smoothing of cast or formed relief where needed, as on repousse or cast and chased items. The aim of such work is to emphasize the existing design; the chaser is the artisan or craftsman who makes the artist's design look even better in sculptural form. He receives the work from the foundry, the casting mold, the electroforming tank or the pressroom and he hand tools each piece to eliminate imperfections – to "remove the warts" – and make it look the best it can be.From the chaser's bench the completed work usually goes to the finishing department which applies color and lasting patina. If the end product looks smooth where it should be smooth, textured where it should be textured, and sharp where it should be sharp, then the chaser has done his job well. Often this is so subtle it is undetectable. Thus, the public seldom learns of the skilled handwork of the chaser and his effort is mostly unnoticed and unsung.Wide Variety of Chasing Tools The chaser uses some of the same tools as the engraver – burins, gravers, scorpers and chisels – but has some unique tools of his own: chasers, liners, tracers, raisers, dapplers and matting tools. In addition he uses a variety of files, rifflers, punches, mallets, burnishers, grinders, stones; and chasing hammers.All told a chaser could have 50 to 100 different tools at his disposal. Chasing tools are available commercially, or the experienced chaser will make his own. The chasing hammer is universally used – it is small with a flat head. In use the chaser watches the end of the chasing tool and not the hammer, thus the reason for the broad head.The size of the piece and the area to be worked dictates the selection of the tool to be used, some of which are described below in what the tool accomplishes.Removing Raised Lines, Bosses & BurrsThe nature of casting, no matter what size or kind, is such there are always tiny flaws that need to be removed from the surface. These are generally caused by dirt, trapped gasses, mishandling or accident during the casting. Thus every roughcast has to be chased to remove such surface imperfections. Mostly these are raised bosses, which usually appear near large detail, rims and edges of lettering and detail.Raised lines, lumps, blisters, bosses and burrs can be chiseled away, ready for smoothing. Dirt causes blisters. Trapped gas that caused pits in the pattern will cause bosses on the piece cast from that pattern. Electroformed or galvano pieces all need attention. Any piece that has been machined, trimmed or sawcut may have burrs that need to be removed. All these receive the attention of the chaser.While not as prevalent as in casting, diestruck pieces can also have raised imperfections (particularly from older dies). Diecracks, diebreaks and fractures in the die causes lines on the struck piece. Holes or dents in the die causes raised bosses. Rusted dies have rust pits in the die and raised nodules on the struck piece. Medals with insert dies need to be cleaned up generally (a line usually forms around the insert where it seated in the die).Chisels are used foremost to remove raised lines of bosses. Smoothing is then accomplished by burnishers, by grinders, by stoning or by emery cloth. Removing Pits, Holes & NicksPinholes and more serious dents, gouges, holes and pitting are removed by burnishing. The concave area is filled by moving adjacent surface metal toward, and filling in the unwanted depression, feathering the surrounding area until the depression is no longer perceptible to the human eye.Removing a hole in the field where the surrounding area is flat is less difficult than repairing a hole where this is in the detail or relief. Care must be exercised so the artistic effect of the detail is not lost to the viewer. Edge nicks are a more serious problem also, because of the difficult of drawing metal from the area surrounding the nick.Planchet flaws infrequently present work for the chaser. Cracked or defective planchets, laminations or alloy imperfections generally leave sunken furrows with sides folded over from die striking. If it is necessary to save the piece (rather than rejecting it and striking another) the chaser can remove the imperfections by burnishing and smoothing.Diestruck pieces may also have "lint" marks, ghosting (or suction) marks, or more serious impressed foreign objects (dirt, scrap, diechips or such) which need to be removed and chased.The burnishing tool is most used for this work. It is slightly curved, comes to a point, has a polished surfaces and is very hard.Patching HolesFor the most serious holes where it is impractical to draw metal from the surrounding area, a patch or plug must be made. Undercuts are made all around the hole to build a mortise. A plug of the same metal as the piece being filled is hammered in, cut off and smoothed out flat with the surrounding area.Deepening ReliefIncised detail can be emphasized by the chaser. Here he would use some of the engraver's tools to carve out metal where lines and crevices need to be deepened. He can enhance lettering by sharpening up their from and serifs. Specifically for diestruck pieces he can work on clogged letters and filled dies. Tiny projections on a die (like the open top of a cap A) are susceptible to breaking off in the die leaving a filled area on the struck piece. These are cleaned out by the chaser. (This work could have been prevented by the champs levee process.)An annealing distortion or worn die may leave indistinct detail on the struck piece. If it warrants, the chaser can deepen this, as well as enhance lettering, monograms and small relief. He may also work on the die itself – recutting, reengraving or refurbishing the die (if an engraver is not available to do this).Any tool that can "bite in" can be used for deepening relief: burins, gravers, chisels and such; often with a mallet.Smoothing SurfacesThe grainy surface of a casting most often needs to be smoothed out; this occupies more time of a chaser than any other activity. Smoothing of a flat field is easy for the experienced chaser, more care needs to be exercised for surface detail and relief. Smoothing usually removes all tool marks and other small imperfections. In addition to finishing pieces, smoothing is also done on metal patterns and some molds.The smoothing is accomplished by burnishing, by filing, by lapping, by grinding (both hand and mechanical), with emery or oil stones, or by hand with emery cloth, or by polishing with any of several polishing compounds. Matching or Adding TextureBy the use of special tools medallic surface may be given texture or background design. When a large detail is smooth, for instance, the artist may want texture in the field for contrast. The chaser can accomplish this in a variety of textures: crosshatched, checkered, dappled, matte, mottled, pebbled, shaded, speckled, stippled and striated.Most of this is performed in the field of the piece; when chasing work is done in the relief the chaser must, of course, match the molded relief or adjacent texture, whatever that is.Each of these surface textures has its corresponding tool and here is where matting, dappling and chasing tools come into play; again often used with the mallet.Trimming & Miscellaneous Work Some trimming is done in the pressroom with trimming dies – all other trimming is done by hand and this is the responsibility of the chaser. The openwork, piercing, silhouetting is done by a chaser with a jeweler's or coping saw on small pieces, band saw on larger pieces. He must remove the burrs after this, of course, and continue with normal smoothing and chasing where needed.A variety of other functions can be done by the chaser, although these are infrequently called for. These might include brightcut or surface scraping for a jewelry finish) or such chores as inlay work.Chasing Repair & RestorationImpaired medals may be repaired (coins are seldom repaired other than plugging a hole). The chaser can plug holes, remove spots and corrosion, repair dents, gouges, scratches and edge nickels – provided these are not too advanced or too serious.The first step is to delacquer and clean, then determine the base metal of the piece to be repaired – (usually an experienced chaser can do this by observing color and testing hardness). If the piece is plated he must first do a reverse plating (stripping away the plated material) before proceeding.Then he performs his chasing work on the base metal; replating (if necessary) then applying the finish – antique or whatever – and finally relacquering. Generally this restoration work is on a small area (or small medallic item) and the tools used by the chaser reflect these size requirements.EnchasingCreating raised relief design – not by striking or embossing – but by raising a design on the surface of metal is called enchasing. The surface is brought up by chasing tools, creating raised bosses, or by indentations, called flutes. Examples of this might be a watch case, but this would only be for a one-of-a-kind item, because of the ease of producing this form of relief by embossing.
excerpted with permission from
An Encyclopedia of Coin and Medal Technology
For Artists, Makers, Collectors and Curators
COMPILED AND WRITTEN BY D. WAYNE JOHNSON
Roger W. Burdette, Editor