Copyright 2004 Lapidary Journal

Which Wood?

By Derek Levin

Nothing is more permanent than something carved in stone according to the old saying. People have been carving stone, creating gemstones and sculpting for millennia. Still, even with all the recent advancements in tool technologies, the basic process for many carvers has not changed all that much.. Carving gemstone is all basically grinding, sometimes in very awkward places.  For many serious carvers, it is the problem of having the right tool for the job that keeps them awake at night. The reason is simple. Although perfect tools cannot ensure good craftsmanship, inappropriate tools will certainly limit the quality and efficiency of the work.
 
Although there are many different  tool systems on the market, many associated with the dental industry, including impregnated rubbers and plastics, because of the complexity of the tool shapes you’ll need, the best and cheapest way to ensure you have the right tool for a job is to make it yourself. And most often the best way to do that is with wood.   Here’s why.
 
Like all gemstone cutting, there are considered to be four basic stages in stone carving:
1. roughing out;
2. sanding and perfecting;
3. final sanding and prepolishing;
4. polishing.
 
There are many variations of operations that fit in between these -- so much so that the process of cutting is actually a seamless continuum rather than four distinct stages -- but using these as a framework for basic conceptualization is easiest. Where carving presents different challenges from other forms of cutting is that there are places in the carving which are not reachable by the standard means of wheels, burs and laps. They are recessed from the surface and so need special tools to reach them.
 
In carving, these recesses tell all. Like all other art forms, judging the quality of a carved stone is mostly subjective. We often start with what’s called the quality (and perhaps expense) of the gemstone material itself. We then look at the artistic value of the carving. As subjective criteria, these are left to the interpretation of the individual viewer.

The quality of the gemstone material is often based on what different organizations deem acceptable. Beyond that is sometimes rarity. Artistic excellence is even more certainly viewed through the eyes of the beholder. Yet there are objective criteria which often show the most obvious differences between high quality one-of-a-kind gemstone sculpting and millions of other carvings.  The distinctions lie in two areas, the details carved into the work and the treatment of the recesses.  How well those recesses are finished and how well the final finish blends across the whole piece may be the primary difference in quality.  Often a quick examination of a lower quality carving will show awkward lines and contours that are inconsistent or incomplete and the interior of recesses which are dull and unpolished or have a finish inconsistent with the rest. But polish is not the only answer. Often a poorer quality carving is polished, but was either sprayed with an acrylic finish, is a very soft stone, or it was tumbled and lacks finer details. So as with most things, the devil is in the details.
 
To complete a carving well, you will have to hand work absolutely every millimeter of that gem stone with ever smaller sanding grits until you reach your polish. That means that every tool shape you use must usually be duplicated at least 5 times.  But this is nowhere near the end of the story. Without going into a great deal of detail here, it’s important to remember that different gemstone materials require different treatments and even with one piece of stone there may be significant variations in how it responds. So there will still be a lot of experimentation for you to do. Added to that, different people are simply more comfortable with different techniques.
 
Developing your best techniques in gem carving, means keeping two thoughts in mind. It’s going to take time and patience and you’ll need to be very creative.
 
Most of us are not by nature tool makers anymore. We’ve become accustomed to buying the tools, using them, perhaps dressing them, but if they break, buying new ones. For stone carving, we have to start thinking about what tools we can make for the task at hand.
 
Also there is something almost counter intuitive in the tools we use for carving.  There is an interaction between the grit that sands the stone and the medium on which the grit is loaded. The diamond cuts the stone but the background material properly presents the diamond to that specific surface to be cut.  There is a strong interplay between these two components and it’s important to bear both in mind when approaching a carving problem. Given the unpredictability of the stone itself, you may find yourself using different kinds of wood with the same diamond grit on different parts of a stone carving or on different carvings of the same material.
 
The thing that has most informed my understanding of this stone cutting process came twenty years ago on a  trip to Peru. I was at Machu Picchu, the famous ruin of an Inca city 9000 feet up on the top of a mountain. The entire city of stone was built in the 1400s without the use of iron tools. I wondered how they cut the gray granite building stones, some as large as 50 tons, which fit together nearly seamlessly. According to our guide, to cut out these stones, two men would hold sticks, like a two man lumber saw, on opposite sides of the granite boulder to be cut. Tied to the sticks was a piece of wetted string made of hemp or similar vegetative strands and sand. String and sand. They simply kept grinding away in the groove they made adding sand and water and replacing the string, and probably the men, until they cut through. 
 
Carving with wood
 
Henry Hunt of Arizona is generally considered the father of American gemstone carving and he wrote “the book.”  It’s called AMERICAN LAPIDARY: Designing the Carved Gemstone.
 
Hunt reviewed several woods for carving purposes. He also discussed the uses of wood for polishing.  Since the procedures are markedly different, I’ve limited this review to the carving process only. Over time I’ve tried almost all of these woods and also woods other carvers use which are not on Hunt’s list.
 
The woods that Hunt originally reviewed were as follows:
1. Pink Ivory  
2. Ivorywood
3. Gabon Ebony
4. Boxwood
5. Lignum Vitae
6. Maple  
7. Teak.
8. White Pine.
9. Basswood.

For various reasons, I’ve added
10. Holly
11. Birch  
12. Palm
13. Briar.

Hunt also suggests some excellent ways to make the tools from the woods, but with some experimentation, I’ve simplified the task. See Step by Step Pg.

Finding and keeping the wood

Many of the woods on this list are considered exotics and some are also fairly rare. For the woods I didn’t have, I went to the internet for my sources and got most of my woods from two wood dealers, Tradewinds of Vermont, and Techwoods of Pennsylvania. However, given that wood is bulky and not terribly portable, find a source close to you. Another thing about getting wood, suppliers are selling lumber, rather than tool making materials, so you’ll find you’ll have to purchase a larger volume than you need. Since they don’t want to cut off a foot, shopping around can help to reduce the size and cost if an order. One other important issue. You need to make sure that the wood you purchase is well seasoned (dried of its sap) or you’ll need to season it yourself. Seasoning wood properly without a kiln takes months but unseasoned wood is unusable. So ask for seasoned wood and try to store it in a climate controlled place where it’s likely to keep well when temperature and humidity change.
 
The findings on the wood
 
1. Pink Ivory -- a wood from Africa, is Henry Hunt’s #1 choice. It’s a beautiful dark pink wood with many worthy characteristics which I’ve enjoyed having, although it is quite hard, rare and expensive. It shapes easily and holds diamond compound very well, whether the diamond is in an oil or a wax base. It also holds its shape well, and is especially useful with sharp edges for those straight line indentations. Photo of indent in opal. It’s probably not as useful for softer stones or soft curves because it can gouge by cutting too aggressively.  On softer stones below 6 on the Mohs scale I would avoid flatter surfaces because finishing later will be difficult.
 
2.  Ivorywood -- I called at least 5 exotic wood suppliers from east to west coast and was unable to obtain Ivorywood in the dimensions I needed.  It seems to be used extensively for flooring and is being exported from South America primarily in sawed thin strips about a 1⁄2 inch thick. Since that thickness is not particularly useful and since it’s not readily available I skipped it.    
 
3. Gabon Ebony -- is a very hard black wood as the name suggests. It shapes very well and easily and has very little grain. The drawback is that it tends to be very chippy at the edges and kind of powdery in use.  Despite the use of extender oil, it gives off a dark powdery residue that can stick to the stone when carving. The stone thus needs frequent washing for visibility. The wood is only marginal.
 
4.  Boxwood -- I’ve used boxwood as one of my primary stone-carving woods for years. It is also rare like pink ivory but is native the Southern US and is obtainable. It’s quite hard and maintains it’s shape well. It’s a little difficult to shape initially and takes more time to make a tool than many of the other woods, but it holds the diamond well and breaks in by creating a surface residue of diamond, oil extender and wood dust that clings very well to the wood without clogging either the wood or the stone. It cuts the stone reasonably fast and clean but is not as aggressive as some of the other woods like pink ivory, holly or briar.  
 
5. Lignum Vitae -- is reputed to be the hardest wood known.  It is indigenous from the Southern US down through South America. There are various species called lignum vitae according to the Encyclopedia Britannica. The wood is highly resinous and dense and does not hold the diamond well. It is, unfortunately, ill suited for tool making.
 
6. Maple --  I used my native New England sugar maple also known as rock maple. It is the hardest of the north American maples. Because it is coarser grained than many of the other woods, it works poorly in the shaping process and unless absolutely dry, small chunks can pull out. It also checks a lot if not properly and completely seasoned. I didn’t find it a great choice for carving
 
7. Teak  -- is a wood that mostly grows in Southeast Asia and Indonesia and the Indian subcontinent.  It is used extensively in boat building because of it’s resistance to rot and boring insect larva and so is easily available from about any seaside boatyard. Although it seems like an unlikely stone carving wood, I’ve found it quite useful.  It is somewhat resinous and fibrous which makes it a bit awkward for tool making because it sticks in the rasp or file. It’s also not terribly hard, much softer than Pink Ivory or Holly, however it works very well doing a prepolish on harder stones like beryl or topaz. It holds the diamond well perhaps because of the fibers. One drawback is that since it’s less hard, it is not ideal for a consistent edge so that it is not well suited for working in deeper recessions in the stone. But it is a much more aggressive cutter than the hardness would suggest. Use it carefully for it can leave scratches on softer stone like opal.
 
8. White Pine  --  Native to much of the US is readily available. As one of the softer woods and indeed a conifer, white pine is not well suited for carving. Although Hunt mentions it, he doesn’t discuss it much in his book. Since it tends to have a lot of knots, is resinous and checks easily I’d skip it.  
 
9. Basswood  -- is too soft for use with imbedded diamond as a carving implement, but Hunt does recommend it for polishing using cerium oxide. He suggests soaking the wood for several days before loading the Cerium oxide and recommends keeping it wet.  That’s the end of Hunt’s list.
 
10. Holly -- is a native American Wood which is widely distributed and relatively easy to get. It is nice and tightly grained and yet is not awfully heavy or dense. The winner of the AGTA Spectrum award, 2004, for art objects, Ralph Wobito recommended the use of holly. He has a point. It holds the diamond paste very well and seems to cut aggressively. It also works for softer stone like opal as well as harder stones like beryl, topaz and even sapphire. Holly is a winner.
 
11. Birch -- The beauty of birch is that it’s precut for tools. Most standard dowels are made of birch. So too are tongue depressors. Though birch is fairly soft, the fact that it is preformed and comes in multiple sizes, makes it very useful for some detail work. I find a split tongue depressor excellent for very small recesses and drilled holes. Larry Wood a long time award winning carver uses birch or just about anything else even toothpicks.
 
12. Palm -- There are hundreds of varieties of palm that come from nearly every warm semi-tropical to tropical place in the world. Larry Wood uses palm laps from India for some of his work so I tried tracking down some of this. One palm is clearly different from another. What I purchased was a soft, very loose grained tubular material that was not well suited to tool making. So some palms may work well and others may not.
 
13. Briar -- is a much sought after wood that comes from a bush grown in the Mediterranean area. Since it’s used for pipe making and is quite tough and pretty much impervious to heat, I decided to experiment with it. It was worth it. With it’s toughness, I expected it to cut aggressively. It did that, but the cut was also surprisingly smooth. It spread the diamond compound out very evenly and cut evenly too. In opal it made a very nice flat cut, in beryl it smoothed the surface well and yet in both cases I was using finer grit diamond. It also was worthwhile with coarse grit.
 
Lots of woods will work for lots of operations. However, there are so many possible variations to account for in addition to the  wood in tools that experimentation needs to be your watchword. Michael Dyber, an extremely well known carver, makes a distinction between natural diamond and synthetic in the sharpness of the edges when it’s crushed. These days there are also multiple preparations in making synthetic diamond. The oil extenders can have higher or lower viscosity, there are new diamond compounds using waxes instead of oil bases that stick more easily to the wood. There is speed and pressure.  For nephrite jade I often use carborundum instead of diamond to get both prepolish and even polish.  With all of the woods here, you should be well on your way to useable tools, but there is still much more to the story of carving with wood. Perhaps the best advice would be: something so permanent it’s worthy of the challenge.
 
The opal is 120 carats about 48 by 29mm. The rough was contributed by Tibara Opal of California.