The original stone with rounded bottom.
This section follows the progress of a simple in-the-round marble carving from start to finish. The block is one of the two salvaged from the badly split block shown earlier.
Carvings are usually planned in advance. The great sculptors of past ages worked from small clay or wax models, and many went further, executing each piece full size in clay as well. Ordinary wet clay is fragile wet or dry, and falls apart even when carefully handled. Plasticine is much better because it doesn't dry out, and so remains easy to repair or modify indefinitely. It's a dead looking material, but you can spray paint it.
Wax is less frequently used now than in the past, but it's a better choice in every way. It's less fragile than plaster or Plasticine, extremely permanent, and easy to modify or repair. If you opt for wax, a sculptor's wax such as brown microcrystalline wax is good. This kind of wax is beautiful without any finishing, looking very much like bronze. Microcrystalline wax is a petroleum derivative made from the refinery byproducts. Beeswax-based waxes are also good, smell better, and are environmentally benign. Recipes for beeswax-based sculptor's waxes with various properties may be found in Methods and Materials of Sculpture pages 159-16133. Another advantage to wax is that if you like the maquette for it's own sake, it's easy to make a cire perdu mold directly from it, or if you prefer to have it cast by a foundry, you can simply send them the maquette. Wax is also reusable indefinitely, even if it picks up dirt, which you can remove easily by melting it and filtering the liquid wax through cheese cloth.
Your model should be complete, especially anywhere that one mass overlies another. As you work on the model, moving masses around and adding back clay, you realize how hard getting it right the first time, in stone, would have been. Some artists then whittle a second version out of a block of hard Plasticene, wax, or other material, in order to solidify their understanding of the form.
In the roughing-out phase, you can knock off corners of the stone with a heavy chisel or handset, but after that, the bulk of the stone is removed with the punch. If you are using the punch straight in, driving the punch with a manual hammer is very effective. For the oblique stroke, the choice of manual v pneumatic is a matter of taste and working style. The pneumatic hammer is vastly faster than a manual hammer when using claw chisels, edged chisels, or the bush hammer, but the speed difference is less dramatic with the punch, unless your pneumatic driver is large, with a long stroke.
The choice may come down to the degree to which you are carving directly. In direct carving, blocking out is a critical part of the creative process. Therefore, manual punching, with its slower pace, and reduced need for protective gear, makes it easier to view the masses as they develop, and allows the artist more opportunity to refine his or her vision of the piece. An artist working from an exact model has different priorities. When working in this way, with more of the decisions are made up front, in clay, the artist is more likely to see blocking out as simply a chore to be gotten out of the way. With mechanical copying, there is no issue--faster is better, period.
The pictures above show the stone to be carved with the bottom side up. This irregular piece is an off-cut salvaged from a tile-factory, and none of the sides are flat. A punch is used to incise a straight line near the edge, with the bottom of the groove on the desired plane of face. A section of hacksaw blade from a Sawzall, or even carpenter's crosscut saw (not one you intend to use again on wood) can be used to clean up the chiseled lines. Check it for straightness with a steel straightedge.
A similar line is cut on the other side of the block. The lines do not need to be parallel, but they must be on the same plane, i.e., not skewed with respect to each other. If two straight lines intersect, then by the laws of geometry they define a unique plane. The punch is pointing at one line, and the other is the white line edge opposite and to the right. If your lines do not intersect, check for skew by laying straightedges in both grooves and sighting along the tops. If the lines are not skewed, you should be able to find an angle at which the two straight edges line up perfectly. Check visually that the plane defined by the two lines passes through stone at every point you care about.
If the base covers a large area, it can be helpful to cut some extra straight lines across the area to be leveled, intersecting with the two reference lines. In this way, the surface can be chopped into small fields, each of which is bounded by lines precisely on the correct plane. Use the punch to rough out the stone in the plane between the two lines as closely as possible and extend the plane, to cover the entire side. The pictures above shows the use of the punch to flatten the area between the lines. When the base is as close to flat as you can make it with the point, switch to a coarse claw to even it out. Minor high spots can be identified with a piece of plywood covered in colored chalk. The board will rock on any high points, leaving them chalked. Cut them down the marked areas and repeat until the surface is flat. An useful hand tool for the final flattening is the "saw rasp" manufactured by the Shinto Industrial Company. Seen here, this is a modern version of the traditional mason's drag. The face of the tool is an expanded grid of hacksaw blades arranged so that all their edges form a plane.
A faster but dustier way to do the final flattening is with a cup wheel on an angle grinder. Unlike other grinding head shapes, the cutting edge of a cup wheel will automatically seek a flat surface if it is kept moving.
The method described above is an general way to make a flat surface. If the block has flat sides, there's an easier way. The plane of a flat surface can marked on the outside of the block by placing the block, bottom down, on the work surface and using wedges to get the desired plane parallel to the bench top. The picture above illustrates how to use a block of wood to scribe a constant distance from the work surface all the way around the block. The desired plane can then be defined cleanly by cutting along the line on all sides with a rotary saw. For many blocks, the saw will only reach part way to the middle of the block, but it doesn't matter; the resulting leaves of stone can be broken off with a hammer and punch, and the flat sawn surfaces extended by hand as described above. For even greater precision, you can tack a six inch wide board to two equal height spacers, and use it to support a circular saw, with which you can cut perfect lines to the same depth across the remaining unleveled area in the middle.
Use either the pitching tool or tracing tool to knock off large chunks from the corners. To use the pitching tool, hold it at an angle to the stone, rap it once or twice with the hammer to set the sharp edge in the stone, then hit it with a solid blow using a heavy hammer.
The tracing tool or other wide heavy chisel does a similar job. Score the entire intended cut line with several light blows. Then, hold the trimmer in the resulting groove and hit it solidly. The illustration shows the kind of chunks you can easily take off with either technique. The break shown was done with a tracing tool, seen in the background, which was ground from an old brick chisel. A commercially made version of either of these tools, with a carbide edge, is an expensive item.
With the bottom flattened and the big corners removed, the real carving starts. Using the model as a guide, start removing the bulk of the stone with the punch. You can still come in from the edges with the punch, but take small bites--tangerine-slice size at most. Whether coming in from the edge or from a surface, punches will tend to break if you use them deeply enough into the stone that they stick like a stake in the ground. They are intended to be used at a depth where you usually get a chip for each time you strike it. We will be using the oblique stroke only because this is marble, and bruises easily.
A one and a half or two pound hammer is plenty heavy. Feel for the best combination of angle and force for your stone. With marble or limestone, the chips should fly.
You should be removing chips ranging from the size of a quarter to size of a matchbook. If you find that you are often hitting the chisel repeatedly before getting a chip you are probably going in too steeply.
Carving completely reverses this, because stone can only be removed. Even in the crudest blocking-in stage, the sculptor must be always be acutely conscious of the finished surface, because nothing can be put back. In the conception of the work, and in the model, it is the masses are important, but in the execution, the surface is everything. Even at the crudest stage of rouging out, the sculptor must never cut below the level of even the the most superficial details, and thus, must be have an accurate picture of the finished piece from the first stroke of the punch. The more complex the composition, the more precisely the sculptor must understand the masses before the carving starts, because there is nothing in the stone that is analogous to the cartoon that the painter draws on he canvas, and then paints on top of. Because the finished piece must be imagined so accurately at the outset, refinement of the overall desgin does not really occur in the carving stage, except in the simplest, monolithic pieces.
Ironically, though sculpture is ostensibly about mass, the actual process of carving stone deals first and foremost with surfaces, and while painting is ostensibly about a two-dimensional surface, the painting is built up from the inside out. Only when sculpting the simplest monolithic forms does the sculptor work like the painter, continually refining a basic shape into something more precise. This is the essence of why Michelangelo, arguably the greatest painter, and certainly the greatest sculptor of his time, categorized modeling in clay as a branch of painting, and considered sculpture limited to carving.
If there are multiple masses, getting them in the right relationship is unintuitive. The roughed-in masses are much larger than the forms they enclose will be when finished. As each mass is carved smaller and smaller, their positions in space relative will change relative to the other masses, or instance, If two masses just touch in the rough, they will be separated by a significant distance when fully carved.
Undercuts irrevocably commit the masses involved to a particular relationship, so always put them off for as long as possible. Instead, as far as possible, come straight in from the outermost surface of the raw stone toward the imaginary center of the carving. When the roughing-out is done, the center of each mass must be the same absolute distance from where it will finish, not the same relative distance.
The coarse punch work in the example was done using both hand and pneumatic hammering. Air is not really necessary at the pointing stage, but it can speed things up, especially as the work gets finer. As the rough carving proceeds further, a pneumatically driven punch will be used more.
The punch leaves the surface so rough that it is hard to tell what the true shape of the piece is. A coarse claw chisel leaves a more even surface, in which you can begin to see the forms. You'll want to go back and forth between the two tools; as the shape of the piece is better and better defined, one can remove stone with more confidence. To bring the piece to the state pictured below should take less than a day.
In the coarse clawing stage, continue to refrain from making undercuts anywhere that masses will touch or come close together,for example, where the hands rest on the skull, until the surface of the major mass is fully defined. An undercut committs the masses that it separates to a certain range of relationships. Nevertheless, the big undercuts can be opened up carefully with the drill. Hammer-drill only when there is plenty of surrounding stone, and never hammer drill within several inches of the bottom, as the drill can blow out a large chunk on exiting.
A drill can be used to honeycomb out the stone in deep cuts, but there is a danger of splitting the piece when you remove the webbing, and danger of the bit breaking the webbing between two holes as you drill, jamming, and wrenching the pieces apart.
After using a drill to honeycomb stone to be removed, before using a chisel to clear the webbing between holes, first cut the webbing with a saw or grinder. A die grinder, air powered grinder, or a flexible shaft tool, with a coarse carbide burr is good for this. A Kutzall brand structured carbide bit, shown here is perfiect. For fine work, a rasp with teeth on the edge is good. Even a thin web has a lot of compressive strength. if you do use the chisel, use a cape chisel, seen here, with the wedge perpendicular to the holes, so that it will not wedge the stone apart.
It is much better to saw or grind through the webbing of stone that is left between the holes. A die grinder or flexible shaft tool with a coarse carbide burr is good for this. On fine work, a rasp with teeth on the edge is good.
Carbide burrs cut through marble quickly, and leave a fairly smooth cut, but you have to be careful in a tight spot, lest the tool bind, which can damage both the bit and the piece. A burr with a round head was used to dig out the eye sockets after drilling two one-half inch holes to almost full depth for guidance. The tooth chisel was used to finish carving the spaces opened up with the grinder.
Eye sockets are tricky--they are not at all round in the back as one would imagine, but instead form cones that run deep into the skull.
The fine toothed-chisel has made the forms clear enough to show some serious problems. From the angle shown, one is particularly visible. Something seems very wrong with the base of the right thumb--it's way too long. The knuckle at the base of the thumb is too close to the wrist, the three sections are all too long, and somehow depressed towards the palm. Fortunately, there's still enough stone left to correct these defects, as can be seen in the next picture, below.
A crayon of magic marker is very useful. Any area to be cut down can be marked using a simple notation. I use a solid line to indicates the boundary of the cut, with perpendicular lines mark the direction to cut, and parallel lines serve as a contour map, the closer the spacing, the steeper the cut.
The piece is fully roughed out when the claw has been used to get most of the piece to within an eighth of an inch or so of the final surface. The last eighth of an inch is where the real action is--about half the work remains to be done at this point.
An eighth of an inch all around is still a lot of stone--it's the difference between your little finger and a hotdog. To this standard, two masses in the rough can end up as much as a quarter of an inch out of place when finished.
In this step we move from finer tooth chisels to the flat chisel for the main areas. Working over the entire surface with the flat chisel shows the final shape very clearly--at this point its possible to start doing the critical undercuts beneath the fingers confidently, so long as the lower surface is very close to its final dimensions first.
Chiseling the undercuts is dangerous. The chisel is a wedge, and tapping it into an enclosing space, even lightly, can break of the piece you are undercutting. A tiny tap in a tight space can knock off a large chunk of stone. Even a rasp, if it twists or jams can do this.
The safest way to do the undercuts is to use a grinder with a conical carbide or diamond tip having the shaft at the point, with the the bottom of the cone smooth, to cut away the bulk of the stone. Use a rasp to go deeper.
The chisels, roundels, droves, etc., are best thought of as the final step between claw chisel and finishing. They clarify the surface left by the fine claw, but they are a little crude for truly finishing the stone. For carving that will be finely finished, they are best used when the amount of stone to take off is under an eighth of an inch. Any more, and a fine claw is better. For the last sixteenth of an inch or so, rasps or push chisels are better.
The critical thing with flat chisels and roundels is not too try to take too much at one pass, lest the chisel "grab" at the stone and snatch craters into it, obliging you to take that much more stone from a wide area. A sixteenth inch at a time is the most you should be taking at this point in the carving.
As with tooth chisels, the pneumatic hammer is a tremendous time saver at this point, for shaving the piece down to its final shape. Keep the chisels sharp and the power low, and be extremely wary of cutting into undercut areas or gaps. Roundels can be useful for hollows.
You can develop your own set of roundels by grinding the flat chisels to suit as needed. Do not try to turn a straight chisel into one with a curved edge by wearing away at the existing bevels. It's a bad method for two reasons: firstly, it's hard to get the shape accurately, and secondly, all the grinding is done with the steel at its thinnest, making it almost certain that you'll burn the steel See Figure *. The only way to recover from burning the tip is to re-harden and temper the steel.
Instead, shape the curve on the grinder with the tool held perpendicularly to the wheel, quenching frequently. Only when it is fully shaped should you bevel the finished shape, Touch edged tools up frequently with a whet stone as you work.
Working over the surface with the straight chisel will clarify the shapes visually, and you'll undoubtedly discover areas where you want to take off a lot more stone. Switch back and forth between a fine tooth chisel and flat chisel for this. If you have a good idea of what you're after, the size of the errors you discover should shrink rapidly as you approach the final form. Notice the subtle changes that took place between the piece as shown in this section and the next, particularly in the heel and thumb of the left hand and the left side of the skull.
At the stage shown in the picture below , most of the carving has been done with punches and chisels that are struck with a mallet or used with air power. Rasps have been used to some extent on big curves like the skull, and an electric drill, followed by the die grinder, has been used to get into deep recesses such as the eye sockets, under the hand, and the zygomatic arch of the cheek bone. The basic shapes have all been defined at this stage, but the surface is blank, with no details such as dimpling, creases, muscles, tendons, and veins. At this stage, there is about a 1/16-inch of stone left to remove from the surface--it's time to put down the hammer and chisels and switch to rifflers and push chisels. Note that many sculptors would use rasps and rifflers for the work that is being done here with push chisels. It's a matter of taste--either method works. The biggest advantage of push chisels is that unlike rasps, they do not leave scratches that must be sanded out. The subsequent sanding that must be done on a rasped surface removes enough stone to significantly change the shape of the surface, and how it interacts with light. When using a rasp, you allow for this, of course, but sandpaper is a relatively blunt instrument for this kind of delicate work, and slow.
The basic push chisels should have the corners ground slightly round so as not to incise step-like lines at the edge of the cut. The most useful ones for softer surface modulations will have a roundel shape. For large outer curves, a straight edge is better. If you are right handed, you'll hold the metal part of the tool with your left hand, and the handle with your right. It's usually best to hold your upper arms tightly to your body and use your body and shoulders to drive and control the tool, rather than extending your arms. This gives you more control and power, and makes the tool less likely to lurch out of control and gouge something. Don't try to take much stone at a time, just shave it away.
The critical things are that the cutting edge should have an angle of close to ninety degrees, rather than the acute angle of striking chisels, and that they be kept sharp. Touch up the edge on the water wheel every few minutes, as necessary, and don't hone them. They work better just as they come off the grinding wheel.
Keep the work wiped clean with a damp cloth, and use good lighting. At this stage, even minute changes to the surface have a huge visual effect because of the way they can move the shadows around.
Almost all of the modulations to the larger surfaces of this piece, including structures like creases, veins, fingernails, and tendons were done with push chisels. Rifflers were used primarily in smaller areas, and places where there are tight curves. Carving inside cavities and tight spots, such as inside the nose bones, was done mostly with small silicon carbide stones in the die grinder or Dremel tool.
At this point, carving is no longer about mass, but entirely about how light hits the surface; tiny gradations of the surface move shadow and highlight around almost like painting. Therefore, it is important to use lighting as good as you'd want in a gallery.
Grinders are used only for carving small details and in tight spaces--using any kind of power tools on the larger surfaces will grind the life out of your piece when carving at this scale. Push chisels remove stone quite quickly, in a very well-controlled way, and will usually usually shave off the full depth of scratches from a rasp in one stroke. Another danger of using the grinder at any stage is that the eye easily picks up the characteristic semi-circular curves that result, and senses the use of the tool. For no obvious reason, while tool marks from the punch and chisel can enhance the sense of the stone-ness of a carving, evidence of the power tools always seems like a hack.
Decisions must be made at this point about the final surface: will it be polished, tooled to the natural matte surface of the stone, and will the final work any exhibit tool marks? The push chisel leaves a matte surface that is about as smooth as paper. For some pieces, this is may be as smooth as you want it, because some marbles become much more transparent when they are smoothed beyond this level, which can change the appearance greatly. Seeing into the stone obscures the surface modulation, hides details, and exposes internal variations in the stone. Notice the difference between the surface quality at this stage and how it looks in the final picture, when it has been smoothed a little further with sandpaper, exposing smoky streaks in the stone that were completely invisible beneath the matte finish. If this stone were fully polished, these streaks would be much more visible.
The picture below shows the piece sprayed with water. Almost the entire surface has been worked with a push chisel-there has been no use of sandpaper yet. The die grinder has been used in a few places, like the eye sockets and inside the nose area. The apparent shine is the damp surface.
At this point, the problem has ceased to be how to get the stone off, and become one of restraint. The stone begins to seem almost plastic because the surface can be modulated to show shadows and highlights so easily. Rinse the piece frequently, and view it wiped with a barely damp rag to expose scratches and tool marks. This final carving must remove all marks that you do not intend to leave. All bruises should be long gone by now, but you may still discover some. They show as milky areas under the surface.
If you're planning a smooth finish, you must shave down the stone until any bruises are completely gone--they run much too deep to sand away. The marble used in this piece is very hard and rather transparent, and shows bruises very easily. Wetting the stone revealed a bruise that had gone unnoticed with the stone dry--it can be seen in the picture in the middle of the top of the skull. It is nearly invisible when the stone is dry, but it won't be when the piece is smoothed further. This bruise is in too obvious a place to leave, and much too deep to shave away with the push chisel, leaving no choice but to revert to the chisel, and remove approximately an 1/8th inch of stone from the top of the skull. Even this did not entirely remove the bruise, but fortunately, the bone areas of this piece are not to be polished, and the matte finish makes sub-surface flaws much less apparent.
The teeth have not yet been carved.
If the preceding step has been done thoroughly, there should be little to sand. Sanding, beyond what is necessary to unify the surface for polishing is to be avoided--it wrings the life out of a piece. If the work with push chisel and rasp in the preceding step is careful enough, very little unevenness should remain on the surface than cannot be removed quickly with 120-grit aluminum oxide paper.
Follow the carved contours very carefully lest you flatten out the fine detail. If you're familiar with finishing wood, don't be mislead by the coarseness of 120-grit paper. It leaves a better surface on marble than it does on wood, and may even be smooth enough for the final surface of many pieces.
Stopping at 120-grit has the advantage of obscuring minor sub-surface defects and hiding slight color and darkness variations inside the translucent stone. For subtly carved surfaces, suppressing the details of the stone with a matte finish highlights the surface detail. The flesh in this piece will be finished smoothly, but without gloss.
This particular marble can yield an almost spooky flesh, because of its translucence, but if its finished too highly it begins to show too much of the smokey internal variations.
The bone will have a different texture from the hands in the finished piece. The realistic bone texture on the face will be achieved by texturing the chiseled surface slightly by just touching it with a very small rotary grind stone. Marble isn't perfectly homogeneous--it is made of tiny crystal grains in a softer matrix. When abraded with something too small to bridge across the hard grains, a very slight lumpiness emerges because the softer stone wears away faster. For this marble, the lumpiness is so on the scale of very fine sand, and it looks very much like the texture of bone. A small light stone was allowed to barely dance on the surface. A similar effect can also be achieved with a rotary wire brush on a Dremel tool, or even by striking the surface with a the bristles of the brush. The wire bristles break off and can be thrown quite hard, so wear your glasses.
The teeth were entirely carved with a very sharp 1/8-inch carbide-tipped lettering chisel, used without a mallet. The outline of each tooth was scratched in with the corner of the chisel, and then the chisel was simply pushed up to the scratched line repeatedly to shave out the shape of the tooth. Despite the fine detail, this was quick--about an hour. The view below shows the piece with everything that will be sanded finished to the 120-grit level.
Don't think of 120-grit sanding as polishing--think of it as the finest level of carving--a swipe with this grit removes a few 1000ths of an inch of stone, and the effect can be very visible, greatly altering the way shadows fall on subtle features. Vary the lighting as you work to be sure of the surface. This is the step that determines the final exposed surface of the stone. Tear the paper into strips with a straightedge (sandpaper destroys scissors). Fold the strip so it has several layers. The sandpaper on the back will provide enough traction that you can retain fine control when you push it. Do not use any kind of rubber block, as it will ride over all the details. The folded sandpaper grips you skin nicely, but after a while it scours the skin off your finger tips leaving an painful raw strawberry. To avoid this, wipe your finger tips with white or yellow carpenters glue, like Elmer's Wood Glue. Blow on the glue until it is tacky, and then dust them with fine sawdust or marble dust. Repeat a few times until you have tough skin that will protect your fingers all day. When you're finished, it peels off like sunburn or washes off with water.
Keep inspecting for scratches, dings, and steps left by the push chisel. Further sanding with finer paper will not remove them--you must get them all out now. Use light across the piece to highlight the surface. If you started with 100-grit, repeat the process with 120-grit or 150-grit aluminum oxide dry paper. It should be faster this time, but continue to be scrupulous. If you want the surface smoother still, switch to black wet-or-dry paper, starting with 220 grit. Keep a bowl of water next to the work to dip in, and keep it wet, refreshing the water often. You can feel when your exposed piece become dull, so change often; wringing every square centimeter of smoothing out of a one dollar sheet of sandpaper is a poor use of your time. Unfortunately, the glue trick doesn't work with wet paper, which still wears away at your skin. But if you've done the first steps carefully, the 220 step should be quick. When you're done, wash again and examine as before.
Scrubbing with 220 can still remove a noticeable amount of stone, so its important to keep your eyes open and follow the contours. Beyond 220, the effect of a single sanding is very small, so one need not be quite so scrupulous. Proceed this way through the grits: 220, 320, 500, 600, 1000, until the surface is as shiny as you want it. 1000-grit leaves it almost glassy. You can roll the polish back by reverting to a coarser grit if you find you've gone too far. Finishes similar to 1000-grit were popular for flesh in the Renaissance and Baroque. The Christ in Michelangelo's Roman Pietá has a finish somewhat finer than 1000-grit (It was actually done with shark skin, not sand paper). This piece will have a 600-grit finish for the flesh, and 120-grit for the dome of the skull. The texturing of the face was described above. To give it a finished appearance, it was gently scrubbed with 320 grit paper that has already been used and is thus very flexible. This gives a very slight luster to the highlights without removing any of the texturing.
No areas of this piece were polished, but after the 1000-grit step, paste rouges can be used to obtain a mirror finish. Like sandpaper, they come in a range of grit fineness.
Marble stains and yellows easily when touched, and people cannot keep their hands off it. Treat the finished washed and dried piece with marble sealer.
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