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

Creating a working space

Choosing a turntable

Height adjustable turntable for modeling
Height adjustable turntable for modeling
Turntable for modeling to put on a table
Turntable for modeling to put on a table

The sculptor generally uses a turntable to put his sculpture at the correct height to work. Furthermore, turntables allows him to easily turn the sulpture during the work.

It's better not to use turntables to put on a table because they don't allow to adjust the height to the sculpture, which is a problem for the strength an the accuracy of the use of the tools, and it may cause back pains. Furthermore, they are so light that the stone might fall during the work!

Never work in a constraint position (twisted or curved back, bended head, curled legs...) for too long, it might hurt at the end of the day, it's better to adjust the height of the turntable.

I also advise to take breaks regularly and do some stretching exercises (with a brush stick for instance) to stretch your muscles from the tiring and contractions of an enthusiastic work.

Low and solid turntable for large-size sculptures
Low and solid turntable for large-size sculptures
Height adjustable turntable for sculpture with a crank
Height adjustable turntable for sculpture with a crank

There are many different types of turntables to be used for sculpture, to work on stone, the main quality to look at is the stability because of the weight of stones and the vibrations created by the work. It's important to respect the maximum weight written in the technical instructions. For large-size sculptures there are low height turnables which allows to work comfortably.

Some turntables have cranks to adjust the height easily even with heavy stones. They allow a very comfortable work always at the correct height.

Wooden wedges and sandbags

Stone sculpture held in position with sandbags
Stone sculpture held in position with sandbags
Stone sculpture held in position with wooden wedges
Stone sculpture held in position with wooden wedges

When working on a stone, all necessary precautions should be taken for the stone not to fall and break (some bones might also break...). The stone should be manipulated with precautions but it's important to make sure that, when placed on the turntable, it doesn't move, even during the work. That's the reason why you need to stabilize the stone and never work on it if it moves even slightly!

A useful way to stabilize the stone is to use sand, which can be put in canvas bags to be easier (and cleaner) to use. It's a good idea to create different sizes of bags to use the bag that fit the best to put the stone in the needed position.

Wooden wedges can also be useful to put the stone in a good position. If you simply need to put the stone in it's final position, wedges can be used directly, if you want to work on the stone, don't put them in a direct contact with the stone, always put a clothe or a sandbag between the stone and the wedge.

Workshop equipment

The workshop of a stone sculptor requires to be equipped with a number of useful tools, which can be acquired according to needs.

Bench grinder

Bench Grinder
Bench Grinder
Silicon carbide grindstone
Silicon carbide grindstone

A bench grinder is an essential tool in a workshop because the tools used for sculpture, as points, scissors, gradines, quickly wear out when used. As it is often difficult to find a professional to sharpen them, the sculptor should rather do it himself with a bench grinder and some grindstones.

Bench grinders are generally equipped with a grindstone with big grain and one with finer grain, both being used to sharpen steel tools. To sharpen tungsten carbide tools, it will be necessary to get a specific grindstone of silicon carbide, generally the color of this grindstone is green.

SThe sharpening tools is a delicate operation because you should not bent the sharp edge of the tool, it is thus important to use the supports in front of the grindstones and to use your fingers as marks to determine the angle of approach of the tool. Furthermore, with steel tools, it is necessary to be very careful not to warm the metal because then the tempering of the tool risks to disappear and the metal will become soft again. It is thus necessary to proceed by quick and ferm movements or to keep close a glass of water to dip the tool as soon as it warms up (but it is often already too late).

Hoists and lifting tables

When working on large size stones, it is often problematic to manipulate them, in particular to lift them up the turntable they will be worked on. It is then recommended to choose a device adapted to lift heavy loads and thus avoid injuring yourself when lifting them.

Manual chain hoist
Manual chain hoist
Electric chain hoist
Electric chain hoist

The most generally used lifting system is the hoist which has to be hung on a very solid fixation (beam of soutainement) existing or to create. For the installation of a tackle, rather call on a professional to be sure of the solidity of its fixation and the solidity of the structure to which the hoit is fixed, he will make sure that the structure of your workshop can bear the maximal weight indicated for the hoist or will take care of the installation of a solid rail. Think as well about the location of the tackle, especially if this one is static, so that you do not have to move any more the stone once this one is on the turntable you will work it on.

You can choose between a manual chain hoist or an electric one. Hoists are designed to multiply the strength given, they thus allow to lift important loads, even the manual ones. Whatever model you've chosen make sure to carefully follow all the instructions of use and maintenance, and especially the maximum load indicated by the manufacturer, to avoid any serious injury.

Lashing strap with tensioning device
Lashing strap with tensioning device
Lifting table
Lifting table

To use your tackle, it will be necessary to use lashing straps along with a tensioning device for a better tightening. Attention to choose a strap which strength matches the weight of the block to be lifted and, before using it, check out every time that the strap is in good condition (if you find the slightest tear, change of strap!). During the lift, be careful to well fix the straps around the stone so that it cannot slide and to ensure the block is balanced so that it does not swing during the manipulation.

If you don't have a solid enough fixation place in your workshop, as I do, you can use a lifting table to lift heavy blocks. You will have the choice between manual or electric models, manual models being endowed with a hydraulic pump activated by foot which reduces the effort. You will also choose the model adapted according to its capacity of load and its maximal height (there are models with double scissors which rise very high). As when using an hoist, be sure to follow well the instructions of use and maintenance and always load heavy weights in the center of the table to avoid that it falls over.

Transporting devices

Transporting device
Transporting device

For the transport of heavy loads, the choice of a quality transporting device is essential. Make sure to choose a solid, steel model, adapted to the weight of the stones you're using and with a large enough size platform. Pay a special attention to the quality of the welds of the transporting device you will choose, it is what will guarantee its life expectancy. You will have the choice between full or inflatable wheels, in the last case make sure you inflate well the wheels before each transport.

I have, besides a heavy and solid transporting device, light and foldable ones much more adapted for the transport of small size sculptures.

In every case, do not forget to always solidly fix the weights to the devil with carrier straps or tensioning devices to avoid that they fall over, especially if the ground is bumped.

Protecting items

Protecting yourself when working on stone is a very important aspect of the work, indeed an accident can easily happen and be very dangerous considering the weight of the material. Moreover stone produces dust and splinters wich may affect your health. The protecting equipment is very important and must not be neglected. In this article, the only protecting items I'm considering are made for working without any electrical tools (drills, grinding machines...), if you're using such tools, think about adapting your protections to the specific dangers of those and reading carefully the precautions of use.

Eyes protection

Protecting mask
Protecting mask
Protecting goggles
Protecting goggles

When working on a stone with a hammer, it's important to use protecting goggles that cover the eyes and protect them from splinters (especially with marble stones!). Those goggles must cover the eyes completely, even on sides. The best for a total protection is the protective mask that protects from rebounding splinters even if it's not always very comfortable to wear all day long.

Be careful never to rub your eyes if itching or if a splinter gets into it. Always prefer using cleaning liquid for eyes and if you can't get the splinter out, check a pharmacist or a doctor. Be careful with splinters in the eyes, they might scratch with painful and crippling consequences!

Respiratory system protection

Dust mask
Dust mask
Protective mask with particles filters
Protective mask with particles filters

The stone emits a large quantity of dust, as you'll notice especially if working on soapstone! This dust shouldn't be breathed in order not to accumulate in the lungs. It's better always to work with a mask, even if it's not very comfortable, especially when working on that type of stone or with a riffler that produces a very fine dust.

Different types of professionnal masks do exist. When working without electrical tools and on non toxic stones (serpentine stone produces asbestos emanations for instance), simple dust mask are efficient enough to stop the particles. Take also good care of cleaning regularly your working space to avoid a big amount of dust!

The disposable dust masks have three particles penetration rates (FFP1: 22% maximum leakage rate - FFP2: 8% maximum leakage rate - FFP3: 2% maximum leakage rate).

When working with electrical tools or on stones with toxic emanations, you will have to use a mask with suitable particle filters. Three rates are available depending on the filtration efficiency (P1: Low efficiency filtration - P2: Medium efficiency filtration - P3: High efficiency filtration).

Ears protection

During the use of electric or mechanical tools, the sound volume of the work can become very high, it is then important to protect its ears to avoid any loss of hearing or the other inconveniences as the appearance of tinnitus. You will find in the DIY stores helmets with different levels of protection or more discreet ear plugs.

Body protection

Protecting gloves for delicate works
Protecting gloves for delicate works
Robust plastic gloves
Robust plastic gloves

Working on stone is a manual work therefore hard for hands, to keep your comfort a regular hydration is necessary (you can also hydrate carefully your face because of drying dust). Using gloves may also protect your hands especially when using cutting (wood chisels or gouges) or rough tools (rifflers). The main point is to use comfortable gloves, allowing skin to breathe, protecting enough but with a good ease of the hand and keeping the touch of the stone.

After trying different types of protecting gloves, I've chosen those for delicate works for their comfortable feeling while protecting the hand. The default is their fragility, especially when working with riffles, holes appearing shortly. Then I'm used to turn them to continue my work or when too damaged I have to buy a new pair (luckily they are quite cheap).

When polishing a stone with sandpaper or compressed stones, working with your hands in water might be painful. Robust plastic gloves may protect your hands from small cuts and cold.

Safety shoes with reinforced toe cap
Safety shoes with reinforced toe cap

When working with electrical tools you have to adapt the hand protection to the tool used. The use of robust protecting gloves is an obligation if you care about keeping all your fingers safe.

Last point, if working on heavy stones it might be safe to wear safety shoes, with a reinforced cap to protect toes from falling stones. As a general matter it's better to always wear closed shoes, even in summer time.

 

 

 

 

 

References Read more: References

Read more: The tools The tools

 

 

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