Techniques - StonePrint this page

Techniques - Stone

  1. The working environnement
  2. The tools
  3. The different types of stones
  4. The stages of a sculpture in direct cut technique
  5. References

Définition

The direct cut is a technique of sculpture consisting in working a material by removing from the material in a direct way, which means without reproducing a model previously realized, contrary to the reproduction techniques. It is a very pleasant technique because it allows to be guided by the material, here the stone.

I will explain on this part, in a totally subjective way, the approach I've adopted to work on stone, a way for me to share this wonderful experience, the direct cut sulpture.

The conception

Working with the stone

There are two methods to work a stone in directcut: define a project and choose a stone which corresponds to it, or choose a stone and decide from its shape which sculpture arisesin your mind. For my part, I work most of the time from the stone, inspiring myself from its shape or an element in it to find the inspiration. The trigger can be the shape, an element of color either a part of the particularly beautiful rough stone.

For this stage it is necessary to observe the stone under all its angles by placing it in diverse positions (propping it up well with sandbags and/or wooden wedges) to get familiar with its shape until one of these positions suits. For my part I take time for this stage, I keep the stone not far on a turntable and I look at it day after day. Sometimes the inspiration comes immediately, sometimes it is longer, but it is necessary to free its spirit without preconceived ideas.

It is then necessary to make sure that the global shape (from all angles) gets well in the volume of the stone because in direct cut, you can only remove the material and not add it. It is possible to draw with a chalk on the stone on each of the faces to visualize more easily how you're going to position the sculpture in the existing volume.

Working with the faults

Certain stones can contain faults or parts difficult to work because fragile or turning into dust when hitten (because of the infiltrations of water). The damaged parts must be identified at the beginning of the sculpture to choose the best way of handling them and avoid any disaster afterward. For certain stones as marble or limestone, the presence of faults in the block can be identified by banging the surface of the stone with the hammer, if the sound is clear it means the block is healthy and can be thus worked confidently.

The parts turning into dust or too much damaged must be removed at the beginning of the conception so that the chosen subject takes into account the new shape of the stone. They must be removed of course by working in plan, and not by digging a hole! Once all the damaged parts are gone, the work can begin. You shall proceed the same way for faults of an important size or situated in border of the stone, it is often better to break voluntarily a fault during the design phase than to having a stone which splits in two at the end of the work when it is generaly too late to reposition the subject...

If you wish to keep some of the faults or for slightly damaged zones, you'll have to work with a special delicacy, always in the direction of the fault to avoid opening it. To limit the risks of break, it is also possible to use as a precautionary measure some liquid cyanolite glue you'll make flow into the fault so that it spreads in the stone and solidifies it. This operation must be regularly redone when you take away material because the glue does not penetrate deep into the fault. Be also careful when polishing the stone with water because the water penetrating into the fault weakens deeply the stone, most of the breakages I had to go along with occurred during this phase when manipulating the stone to polish every angle.

If the stone has already broken, you have two solutions: modify the subject to adapt it to the new volume or restick carefully both pieces. If the break is too important (stone broken in the middle of the subject) you'll probably have to change your subject because you won't be able to hide the crack. Generally I keep all the broken pieces in my workshop for later when I shall want to make a small sculpture. If the break is in a corner, it is necessary to try to see if a minor modification could adapt the subject to the new volume. When the broken piece is essential, you can try to use glue on the stone. I use a specific glue called Stéacolle who makes the job very well, even if I ignore what its exact properties are... For an optimal result it is necessary to work again a little the zone stuck after drying (knocks of tools or polishing) to hide the limit between both parts.

Drawing on the stone

Examples of drawing the axis of the subject on the stone Examples of drawing the axis of the subject on the stone
Examples of drawing the axis of the subject on the stone

Throughout the realization of the sculpture, it is important to draw on the stone to avoid loosing the shape and the plans, in particular when you need to work the stone in a position which is not its final position. You can use chalks (for the soapstone I use Crayola because they are bold and stand out well), paper pencils (there are specific ones, green, to draw on the stone). To note that there are also tungsten or diamond pencils to draw finely on hard and smooth stones, but they are mainly used for engraving.

The drawing has several main objectives: at first mark the places where you musn't work anymore by drawing an outline with a cross in the middle (the outline a little wider than the exact zone to be certain not to go too far) to be sure not to tuch these zones. Then you can draw the various axes of the sculpture, in particular when working on a subject with a central axis (as a face or an animal for example), it allows to make sure not to divert the axis during the work, what could be very problematic. For the face you can also draw the big zones as the forehead, the nose and the chin (vertical division in three parts) to make sure that the volumes and the plans will be in correct position.

Later in the progress of the sculpture, we can use the drawing to mark more precise points of the sculpture and be able to make sure before realization if they are correct. By continuing on the example of the face, we shall draw eyeballs and we shall make sure that they are well both of the same size, we shall draw the mouth and make sure that it is not twisted... Then we will be able to follow these drawings to realize these elements.

To summarize, the drawing has to accompany all the process of sculpture in every stage because it is the only way for the sculptor who works in direct cut to make sure that his idea will be accurately realized because the stone is sometimes misleading and what you see is not always the truth (a cloud or a difference of color in the stone is enough for the eye to be deluded), while with a pencil you can draw with a ruler or a square edge you might feel or see if there are deviations in the lines. Of course, as you're removing material, it is necessary to redraw the lines when they disappear.

Making a model

Marble sculpture and it's clay model
Marble sculpture and it's clay model

Before beginning a stone sculpture, it is possible to make a model, for example in clay, which will be a useful guide. If this model is made to be transcripted exactly in the stone (by taking measures etc.) then it's not a direct cut sculpture. A model is however very useful to visualize the subject, in particular if it's a complicated one. It also serves to show the project before realization to someone like a teacher for example.

I think it is important not to be imprisoned by the model because major differences exists between clay and stone and it would be a pity not to take advantage of it's specificities. The model must be considered only as a global approach of the volumes that may guide you through the rough-hewing steps of the sculpture.

Roughing and planes

Importance of the planes

Importance of the planes
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Importance of the planes
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Importance of the planes
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Importance of the planes
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Importance of the planes
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Importance of the planes
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Importance of the planes
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The most essential thing in the direct cut technique is the notion of planes because, contrary to the modelling, you can't put back a volume which would have been removed by mistake, nor to move an element which would have been badly placed. The better way to avoid such problems is not to create the forms, the volumes, the blacks and the details at firts but to concentrate on the global volume of the sculpture by forming it by planes (a curve is difficult to define and to visualize while a plane is always clear). Thus the global form of the sculpture will be created by a serie of planes gradually more and more precise.

Still with the example of the face, here some steps of work to help understanding this approach:

  1. First I draw the vertical axis in the middle of the face and I do an inclined plane on both sides.
  2. I divide the face in three equally large horizontal parts and I draw the horizontal axis from the higher point (the top of the nose, two thirds above, one third below) and I do an inclined plane on both sides.
  3. I redraw the three parts and I create a flat plane for the forehead (upper third) which allows me to incline more the plane of the nose.
  4. I create the planes for the mouth from it's horizontal axis (half way between the top of the nose and the bottom of the chin) and for the chin, the planes on both sides of the nose (in a triangle shape) and the axis of the eyes on the axis of the upper third of the face (being careful that eyes are balls with an important volume).
  5. I draw the sides of the face and I create the sharp planes that will surround the face, but I'm careful not to remove the volume of the cheekbones.
  6. I incline more the planes and bend them when necesary until I'm close to the real volumes.
  7. Only now I begin to do the details of the sculpture.

Working with the tools marks

Exemples of tool marks on the fur and the mane
Exemples of tool marks on the fur and the mane

Every shock received by the stone leaves a more or less deep track according to the strength and the angle it is given. It is thus important during all the stages of the work to pay attention not to leave too deep tracks in the stone, because they would need to take off a lot of material to be erased. If the piece is afterward polished, it's necessary to take away all the marks of tools with the riffler, it can be a long work because the marks can be very deep,and some parts of the sculpture might even have to be redone...

If the sculpture doesn't need to be polished, the marks of tools will create what's called a writing, which means a set of tracks that leads the eye of the spectator through the volumes of the sculpture. It is thus important to create a beautiful writing, which means in accordance with the volumes of the sculpture. To get used to it, it is important from the very beginning of the work (even if you are still very far from the final volume) to work always in the direction of the volume. Then you will also be able to stop your work as soon as the volume is right, without having to remove more material to create a nice writing.

To make sure to create a beautiful writing and to limit the visible marks before the polishing, there are several useful advice to be respected. First of all find a regular and relaxed movement which will assure the regularity of the writing and will avoid you to create too strong knocks. The hand holding the tool must be relaxed, the tool can slide in the hand easily, muscles are not wrinkled, the arm holding the hammer is also relaxed in a large movement. When the hammer strikes the tool, both arms continue the movement. This way of working assures the quality of the knocks, but also allows to work for long hours without getting tired and to avoid aches or bad vibrations that may cause articulatory problems.

The angle of the tool on the stone is an essential parameter to avoid deep marks or even breaks of the stone, the tool must never hit the stone with a straight angle, but always slide on its surface and remove a little bit of material at every passage.

Last but not least, attention never to work at the angles of the stone towards the outside, always put the tool towards the inside of the stone to avoid the breakage of the angle.

The volumes and the blacks

Once the planes are set up, time has come to work on the volumes to give to each part of the face its definitive volume (a little bigger because the polishing will use the volumes). It is a very important step because volumes and blacks have to be placed on right places.

The creation of the volumes will form "blacks", which are the shadows created by the meeting between two volumes. The work on the blacks is particularly important because it is them that will emphasize the volumes of the sculpture, they must be thus drawn well, which is a rather long work. Make sure before creating them that they are placed well because otherwise it will be necessary to re-level all the surface and to begin again the volumes and the blacks. That might represents a lot of work and a big loss of material!

Refining the shape and erasing tools marks

A range of rifflers from biggest to smallest...
A range of rifflers from biggest to smallest...

Once the general shape of the sculpture created, it's time to refine it to approach the final appearance, taking care to remove the deepest marks of tool in the stone. It is obviously important to avoid as possible creating new deep marks of tools that you would have to remove later...

If the marks are deep, it will be necessary to remove them with a chisel used delicately not to leave new marks. Then you will make sure to remove all of the marks on the sculpture (in particular in the blacks!) before using the rifflers and begin the polishing.

If the marks are shallow, if they were already partially removed or if the stone is very soft, you can directly use a riffler. The riffler is going to rub the surface of the stone to remove a little bit of material and will be leaving light tracks which it will be necessary to remove with a smaller rifloir and so on... As this work might sometimes appear long and boring, it is important to make sure before beginning that there are no deep marks that would require to remove a lot of material because then it is easier to begin with the chisel.

Polishing

Once the definitive shape done and the marks of tools erased, the polishing, last stage of the sculpture, can begin.

I often make a stage of polishing during the work of the sculpture, so I can see the appearance and the color of the stone before having totally fixed the shape of the sculpture and then it's possible to modify slightlythe sculpture to get along with the material. The use of the strongest sandpaper or carborundum stone is important to get an idea of the result (generally the 320 is perfect for that, by rubbing energetically you can get a good idea of the appearance of the sculpture once polished). It is particularly interesting when working on soapstones which often reserve surprises of colors and for alabaster to reveal clouds in the stone.

Once the work of volume of the sculpture is done, thus arrives the stage of the final polishing which must be very carefully realized because it is what will reveal the shine of the stone and will emphasize all the work of volumes and blacks by leading the light on the surface.

The polishing is made by successive passages of carborundum stones and/or sandpapers of more and more fine grains. The grains I generally use go from 220 (the roughest) to 1200 (the finest). It is this succession of more and more fine grains that polishes the stone, the first paper removing the marks of riffler, then each paper removing the marks of the previous one. The most important papers are the first one, because it has to remove all the deep marks made by the riffler (the following papers are too fine to do that), and the last one that will give to the sculpture its shining. You will thus have to use them with special care and a longer work. If when using the 1200 paper, you notice that there is a still a mark of riffler, you'll have to redo the whole polishing work from beginning... That's the reason why the first paper has to be used very carefully to make sure that there are no more deep marks before the passage of the following paper. Attention on the fact that once the stone is wet, the marks become often invisible and will appear only when the stone will be dry. It is thus necessary to dry the stone with a soft cloth to make sure that there are no marks left before going to the following paper.

Small advice (but very important): change of water and clean well your sculpture between every grain of paper so that there is no dough of the previous passage that might create new marks as it is what you try to remove! Attention also not to creeate marks with the edge of the paper... Finally, you can use supports on which to place the sandpaper, for example small sticks which will allow to reach the blacks (I like very much plastic tools for Plasticine because they do not risk to scratch the stone if the paper tears apart. You can also place your paper on a shoe's inner sole what will allow you to press more hardly when the stone is hard (very important for marble stone!)

Pay attention to always follow the volumes of the sculpture when passing various sandpapers because, although it does not seem like it, quite a lot of material is removed during this stage (especially on soft stones), then it is important to follow the shapes defined during the work, it is how you will obtain a sculpture on which the light hangs on harmoniously.

This stage ends with the passage on the sculpture of a protective product as polishing paste or wax. The aim of these products is to make the stone shine and protect it. It is necessary to pay special attention to apply these products on a totally dry stone, I got used to always wait at least one night between the end of the polishing and the application of the product, because if the stone is not very dry, the product will not penetrate and will leave marks on the stone. The wax can be applied with a simple cloth and, once dry, polished with a woolen cloth. Avoid to let wax surpluses, especially in the blacks of the sculpture (contrary to wood, the stone doesn't absorb the wax) and pay special attention to use a colorless wax (a lot of so called colorless wax are really yellowy), for instance an antics wax.

About the polishing paste, you shall apply it with a cotton disk fixed on a drill, you press the disk on the stick of polishing paste to soak it, then on the whole sculpture to make it shine. Attention not to bang the sculpture with the drill or the axis of the disk! I used the polishing paste for alabasters and wax for all other stones.

To be notices that some stones, as limestone for instance, can't really be polished, then after sandpaper the best is to apply a water repellent product to protect them.

The base

Choosing a base

Sculpture the position of which is given by its base and which has therefore been worked considering it
Sculpture the position of which is given by its base and which has therefore been worked considering it
Sculpture on an ash base
Sculpture on an ash base

A sculpture is generally placed on a base that allows to position it and to highlight it. The base is an essential component of the sculpture of which it is completely a part (the measurements of the sculpture integrate the base). The base also isolates the sculpture of the element on which it is put, for example a white sculpture on a white base might not be well seen, the advantage of the base is that its shape and its color are chosen to correspond at best to the sculpture. Not to put a base in a sculpture is possible if this one is stable and is self-sufficient. The base might also be a sculpted part of the material of the sculpture.

Choosing a base for a sculpture is an important artistic decision, sometimes the base is chosen from the beginning of the work on the sculpture (in particular when it modifies it's position, it is then important to work the sculpture in it's final position) as in other times it is only chosen at the end of the work, but if possible not totally at the end because the base can force you to do some modifications on the sculpture.

The base can sometimes be a simple wooden or stony plate (that you can find in any stone or wood shop, in particular in their scraps) which completes the sculpture or maintains it in position.

Finding the right base for the right sculpture is not always easy, the size, the shape, the color, the aspect of the base have to match the sculpture, it is necessary either to cut it at the right size (stone, wood, metal, glass, Plexiglas), or be lucky enough to find the good element, where from the interest to collect elements whenever possible (wooden pieces, stones found during walks, pebbles, paved etc.) what will give you a lot of choice.

Drilling

Once the base found and the sculpture ended (the best is just before the end of the polishing, because the drilling can create marks on the sculpture which will require to re-polish, so you can drill before the last polishing phase), it is necessary to assemble them.

It is possible to simply position the sculpture on the base if this one is perfectly flat and the sculpture perfectly stable, in this case no drilling is necessary. When it is not the case, it is necessary to fix the sculpture with its base, either definitively or temporarily. Generally systems of stalks or tubes are used, they can be in brass, aluminum or steel, of a diameter which depends on the weight of the sculpture. They will be stuck in the base and in the sculpture to maintain them together. It is generally better not to fix definitely the stalk in the sculpture and the base, so that you can separate them during transports, what makes them lot easier especially when the sculpture is heavy. It is then necessary to take a lot of care if you want to move the sculpture and the base together to make sure they don't split with your both hands...

The drilling phase which will allow to insert the stalk between the base and the sculpture is a very delicate one because the drilling has to be made in the good axis so that the sculpture rests on its base with the right angle. It is particularly complicated in the case of heavy, and thus difficult to manipulate, sculptures, very small sculptures, very hard bases (granites, stonewares, schists) or of complicated forms or axes.

It is necessary to determine the diameter of the stalk that will be used, it obviously depends on the weight of the sculpture, but also on the pressure it will apply (a sculpture in height will have to have a bigger stalk). The standard stalks go from diameter 4 (for very small sculptures) to 10 (for medium-sized but in height sculptures or large-sized without any pressure), but you can also get bigger stalks for larger sculptures. It should be noticed that tubes are, in equal diameter, always more solid than full stalks. The choice of the metal especially seems to depend on the desired look if the stalk is visible. Precise information on the respective qualities of the brass, the aluminum and the steel in terms of resistance and expansion coefficient to the heat can be collected on specialized websites.

At that stage, you'll have to drill successively the base and the sculpture in the same axis.

  1. It is necessary to determine first of all where the base and the sculpture will be drilled, for that you need to place a mark on one of the two on a place where they make contact if the sculpture rests on its base (like that the stalk will not be seeable) or of a place in balance if the sculpture is positioned in height.
  2. It is then necessary to place the sculpture on its base in the good axis to take vertical marks, for that you can use a mason's square rule to draw axes on the four sides of the sculpture or use a bubble level with a laser projection you will then only have to follow with the pencil.
  3. Then you can separate the sculpture and its base to begin the drilling, always beginning with the base (so that in case it breaks, the sculpture can be adapted to another base) that you put on a very flat surface and drill in (if possible without percussion because there is a risk of break) with the appropriate drill. Note that for very hard stones there are diamond drills which work very well and make holes much more precise (it is necessary to pay attention to spray wellthe drill with water to avoid that diamonds burn under the influence of the heat, what would be pity given their high price). About the deepth of the hole, it is to be decided according to the thickness of the base and the pressure exercised by the sculpture on the stalk.
  4. We can then get to the drilling of the sculpture. It is a little more complicated than for the base because this time we cannot simply put it on a plane surface because it is necessary to turn it over and because its top isn't generally regular. You can place sandbags in a bucket or a basin to help positioning the sculpture upside down. You'll have to find the right position for ths axes drawn previously to be vertical and to prop the sculpture up well so that it doesn't not move during the drilling. According to the type of stone, you can use for soft stones drills for wood, or for hard stones drills for concrete or diamond drills (in this last case, do not forget to make a pre-hole with a point chisel because the end of the drill risks to slide).
  5. The last stage is to measure the deepth of each hole, to add them and to cut the stalk at the right length (don't forget to take off burrs not to mark the sculpture).

The display

The sculpture is now finished and the next step is to display it in different events or exhibitions.

Transportations

The transport is one of the most annoying and stressing aspect of sculpture, especially for stone sculptures because of the weight and the fragility of the material. It is thus important to protect well your sculptures, either with manila paper or clean blankets (I insist on the cleanliness because dirts can mark the material). It is interesting to use transportation boxes, but the difficulty is to find solid enough boxes for the weight of the sculpture. It is possible to create your own wooden boxes with handles. You can also use (it is what I'm doing for stones) thick plastic bin for cement with solidly fixed handles, the advantage of these is that they can be used for a large scale of sculptures.

Pedestals or presentation bases

Wooden presentation base ready to paint
Wooden presentation base ready to paint

Sculptures are generally presented on what is usually called bases, which are high presentation boxes. I prefer to call them pedestals to differentiate them from the base of the sculpture I wrote about above. These pedestals are generally made from wood, closed on 4 sides and paint in white (it is even obligatory for numerous exhibitions, so it's easier to follow that rule). The choice of the dimensions of the pedestal of a sculpture is very important because it is what is going to determine the way the visitor will perceive the sculpture, if the sculpture is too low or too high, the effect might be completely missed!

To note that there are ready to paint pedestals on sale at Boesner (especially in the Champigny store) for those who do not want do odd jobs or in case of emergency. They exist in a large range of dimensions. They are very solid and practical, with simply two wrong things: they are difficult to transport because voluminous (they cannot get dismantled nor put in each others) and they are difficult to hold (I've created handles by drilling a 10cmx2cm hole in the top and the bottom of the pedestal, enough to be able to put the hand which is very handy!).

For the brave ones who want to make their own pedestals, it is necessary to choose some rather solid wood and to take care to assemble the elements well so that the pedestal can support the transports and the weight of the sculptures. To note the big interest to create pedestals that can be put in each others or can be dismantled because bases represent the main part of the volume in a transport of sculptures.

Lighting

The lighting of a sculpture is a major element in the display, it is unfortunately too often neglected in the exhibitions. It can be interesting to create a special lighting set for certain sculptures, especially when these are translucent. The pedestals can be equiped with lights. Don't forget that the natural light is generally the most appropriate for stone sculptures, then if possible get the best from windows and glass roofs!

 

 

The different types of stones Read more: The different types of stones

Read more: References References

 

 

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