Polymetaal

A technical dictionary of printmaking, André Béguin. EN

In printmaking, many are the tools and instruments that need to be sharpened. Knives, gouges, and dry point tools must always be perfectly sharpened. Points must be rolled upon a whetstone until the tip becomes very sharp at which point one must draw a series of circles (first a big one and then smaller ones) on a sheet of cardboard while holding the point vertically. A dry point can also be sharpened in facets so that the triangle it forms will cut a clean line into the metal plate.
Sharpening must be particularly well done in line engraving using gravers. The precision with which gravers, echoppes, and scrapers* are sharpened will determine, to a large extent, the success of an engraving.
The sharpening procedure for a graver is almost ceremonial and requires a good deal of experience.
The bevelled edge must be placed on the stone covered with mineral oil. Make sure that it lies perfectly flat and keep it in place firmly so that there will be no rocking motion. Rub the graver back and forth thirty to fourty times. What is hardest to do is to maintain the same inclination throughout the job which is why the hand must not be moved while the sharpening is being done. The graver can be rubbed on the stone either by keeping one's hand raised or then by keeping one's hand on the table and sliding it along the little finger. When the bevelled side has been rubbed! enough to renew it the time will have come to rub the two lateral faces of the tool (i.e. the faces on the side of the tip). The lateral faces must be rubbed while being kept perfectly flat, held down withia finger of the left hand. Each surface must be rubbed about ten times back and forth so as to get rid of the burr formed by rubbing the bevelled side.
The choice as to what kind of whetstone to use in sharpening a graver is quite personal and depends very much on the type of engraving to be done. The first sharpening is usually done with a fine-grained synthetic stone. The rotten stone used to rub copper plates can also be used. The finishing touches are given with Arkansas stone, which is extremely fine grained and produces a very good result.
lnsofar as concerns work on copper plates, l prefer carborundum sheets rather than stones. l begin with a medium grain for a first sharpening and then go on to a fine grain [abrasives]. Carborundum wetted with mineral oil and somewhat worn down gives a good edge which, however, will not make the tip of the graver excessively sharp. ln fact, the tip must not be too sharp when cutting copper plates since it can penetrate too deeply and even get stuck. When this happens people often think that the sharpening is insufficienl. when, in fact, it is really too well done. Furthermore, carborundum sheets lie quite flat and can be changed very easily when they are worn down. A last advantage of such sheets is that the graver being sharpened will be at the same height as the hand which simplifies the sharpening procedure.
When used on a steel plate a graver must be extremely sharp. Sharpening must be done on quite a hard stone and must be repeated very frequently, sometimes after cutting only two or three lines if the steel plate is very hard.
To check whether a graver is well sharpened its tip should be placed on a finger nail and held at a 30° angle. If the graver slips whithout catching it means that it is not sufficiently sharp or then at least not sharp enough to cut deep lines or for work on steel plates. For work on copper or maybe even on zinc one can try "soft" sharpening which will not catch on the finger nail. Sharpening can also be varried somewhat in function of how deeply or a how shallow a line needs to be cut.
When cutting a plate the grain is usually held at a 55” angle. lf the angle is too great the graver will be too steep and the tip will penetrate too deeply and will catch. Too low an angle will, on the other hand, make it hard to cut the plate.
An echoppe may have a flat or rounded sweep and, although echoppe sharpening is done in much the same way as for gravers (keeping in mind the difference in profiles) their angle must be sharper, ranging from about 25° to 30°. Lining tools, on the other hand, should be sharpened with a 45° angle.
The scraper ur mezzotint scraper (which has three sides and ends in a point) is used to cut the burr produced along the lines dug by a dry point tool. When it is well sharpened it should be able to cut the burr at plate level with a clean edge and will not scratch the plate. To achieve such a sharpness each side must be sharpened in turn beginning the iob with a grained stone and finishing it off with an oiled Arkansas stone.
The sharpening of the rockers* used in mezzotint* work is hard to do because ul the curvature of the blade which must be perfectly maintained. The cutting angle of a rocker should be of about 40° to 45°.
The knives used for cutting stencíls in serigraphy are sharpened on fine grained stones. Some of the blades used are sharpened by the manufacturer and are such that, when the blade ís worn, it can be broken off and a new one will fall into place automatically.