People have been shaping stones for millennia. As a natural material, stone varies widely, and a range of methods and tools can be used to achieve a similarly wide range of purposes. This article will focus on basic techniques that are appropriate for landscape uses and building structural walls with stone. These techniques can often be applied to other types of stonework, such as veneer, as well.

For the purposes of shaping, there are two main types of stones: level bedded (including sandstone and slate) and irregular (such as granite and basalt). Level bedded stone will tend to break easily into flat sheets or plates. Sedimentary stones will almost always be level bedded, as are many metamorphic stones. Igneous stones, formed through the cooling of lava, are irregular, because they don’t naturally form flat sheets or plates, but they may still have a grain that affects how they break.

Stones are strong in compression, but weak in tension. Stones are also weak in bending and twisting forces (brittle). We can use this knowledge to make sure we’re applying force to a stone in a way that takes advantage of these weaknesses. How a stone is supported will greatly affect how it breaks, or if it breaks.

Strike in multiple places along your intended splitting line. This split was done with a Trow and Holden (T&H) tracing chisel and hand hammer.

Splitting is done by applying a force through a wedge-tipped hammer or chisel. The stone on either side of the chisel’s tip is in compression, while the rest of the stone will be in tension, where it’s naturally weak, and this will allow the stone to split. Splitting is best applied in the direction of the bedding plane or with the grain of the stone. Use Stone Busters, a tracing chisel, and a trimming hammer to split stone.

Start removing a high spot by working around the high spot from different angles. Then, continue to hit in several places to tunnel in and remove the bulk of the material. Finish with light taps on any remaining bumps. Note how the point is held at about 80 degrees to the stone. This was done with a Rebit PKM 25, a T&H Chisel Wizard, and a 3-pound hand hammer.

High-spot removal is critical for fitting stacked stones together, but it can be difficult, because directly hitting a bump on a stone puts it in compression, where it’s quite strong. Using a point concentrates the force, causing chips to break off. Using a directional point at the correct angle makes it possible to split off larger pieces. Use a directional point, a point, a mason chipper, and Stone Busters to remove high spots.

Dressing is often done for cosmetic reasons. In this case, a slight “bullnose,” or “rock face,” is created to give relief and texture to an otherwise flat surface. This was done with a T&H mason chipper and 3-pound hand hammer.

Dressing generally refers to final shaping, done with lighter taps, to square up stones or create decorative texture on their faces. The light taps are essentially wearing away or slightly crushing the surface of the stone in a controlled way. Use a directional point, a point, a mason chipper, and a tracing chisel to dress stone.

Bending works best when a mason intends to break near the center of a stone. Several strikes in a line will define where it will break. This break was done with T&H 4-pound Stone Busters.

Bending works well for diminishing the size of flat or long stones. Stones supported at either end and struck in the middle, or struck on an overhanging end, undergo a bending force that will cause most stones to break reasonably easily. Bending is usually achieved by striking several places along the break line. Use Stone Busters, a Quarry Buster, and a trimming hammer to bend stone.

Trimming is often done by nibbling away the area to be removed. Start by undercutting, then shearing through, and finally tapping to smooth the edge. This method is ideal for shaping patio stones. This trim was done with a T&H rock pick (carbide brick hammer).

Trimming is the process of working the sides or edges of the stone. This can be done with shearing force, which relies on stone’s brittle nature to work, but it can also include splitting forces. Trimming is typically done perpendicular to the bedding plane or the grain of the stone. Hitting from the end of some types of stone is much more effective than hitting from the flat side. Use Stone Busters, a mason chipper, a trimming hammer, and a brick hammer to trim stone.

To trace a line, strike in a line around the stone on all sides (if possible). Start with light taps, and gradually increase to hard strikes. This break was done with T&H 4-pound Stone Busters.

Tracing a line is the practice of repeatedly hitting a stone in a line, often on more than one side. This creates numerous microscopic cracks in the stone. When the cracks connect, the stone breaks. Start with light hits and gradually increase the force of your strikes. Tracing a line is precise but slow; it requires many hits. This technique works better with some stones than others, but should be used only when needed, due to the effort required. Use Stone Busters, a trimming hammer, a tracing chisel, and a Quarry Buster to trace a line.

Having high-quality tools when working with stone will make shaping faster (and certain shaping possible), improve your accuracy, and reduce maintenance time. With good skill and experience, however, basic tools can also be used effectively.

Carbide-tipped tools are commonly used by professionals and hobbyists. The carbide keeps the cutting edges sharp far longer (these tools often only need sharpening once a year), and they will work well on very hard stone. However, they’re much more expensive, easily ruined by improper use, and require a special grinding wheel to sharpen. Steel tools are less expensive and are easy to sharpen, but they only work well on soft and moderately hard stone and often require sharpening every week.

A variety of trimming hammers.

Trimming hammers come in many shapes and sizes. Often, they have a head with a square end for trimming and a blade at the other end for splitting. The square end will be used 80 percent of the time or more, so some trimming hammers don’t have a blade at all. A 2-to-3-pound hammer offers good versatility.

Brick hammers are a type of trimming hammer. These lightweight hammers work well with smaller and softer stone. An 18-inch-long handle will give these hammers a lot more power, despite their light weight.

Trow & Holden Stone Busters, which are designed to be hit by another hammer.

Hammers designed to be struck by another hammer, such as T&H Stone Busters, are a game changer. T&H makes a wide range of these hammers, and there are a few made by other manufacturers. The T&H Stone Busters have the precision of a chisel and tremendous striking power, making them the most versatile of these hammers. They’re used by placing the blade of one hammer on the stone (as a chisel) and striking it back-to-back with the other. This eliminates the need for precise aim with a single hammer. The horizontal and vertical blade arrangements allow for good ergonomics without having to reposition the stone or yourself. The Quarry Buster is a scaled-up version of the Stone Buster that’s meant to be used by two people: One person holds the Quarry Buster on a stone, and another hits it with a sledgehammer.

A directional point is a chisel with a 3/8-inch-wide tip. This tool is ideal for high-spot removal, because it concentrates force in a specific area. The small chisel tip allows for quicker material removal than regular points and often does the work of an angle grinder faster and with less dust and noise. The Rebit PKM 25 and the T&H bull point are the two directional points available. True points concentrate force even more than directional points, but tend to remove material more slowly and with less control.

Chisels come in a wide array of sizes and shapes. The wider the blade of the chisel, the more control over the direction of the split you’ll have, but the more diffuse the impact will be. A 1-1/2-inch-wide chisel seems to be a good balance of control and power for many stone types. The sharpness of the angle greatly affects how the chisel works. A tracing chisel with a 90-degree angle is great for tracing a line, but when sharpened to 70 degrees or so, it becomes a fantastic splitting tool. However, it can then become damaged if used against the grain on hard stone. A T&H mason chipper has an offset design that makes it ideal for trimming, despite its blunt angle, because you can drive it deeper without causing spalling.

Chisel handles can protect your hands.

There are a variety of hand guards and chisel handles on the market for reducing the possibility of hitting your hand by mistake. The T&H Chisel Wizard is particularly good, because it’s adjustable and has a secure grip. Plus, it’s possible to hit angles with it that would be impossible when gripping the chisel directly.

Note: Quality stoneworking tools can be quite difficult to source. All the tools in this article are available from The Stone Trust, a nonprofit organization with a mission to preserve and advance the art and craft of dry stone walling.

While detecting the bedding plane of some stones is fairly obvious, seeing the fine grain, hidden cracks, and imperfections can take a lot of experience. Pay attention to the details of the stones you shape so you can become familiar with the telltale signs of the stone type you’re working with. Shaping perpendicular to the grain can be quite difficult with many stones, and some stones are simply too hard, brittle, or unpredictable to be worth shaping.

Gaining practice and experience is the best way to become successful when shaping stone. Different types of stone react differently to different tools and methods. Skill is gained by paying close attention to the details and results of your attempts to shape stones. Modify your approach, tools, or methods when you don’t achieve desired results. Getting strong enough to have a fast, accurate swing with a 3-to-4-pound hammer is critical to efficient shaping with most stone types. There are dozens of additional hand and power tools, methods, and techniques for shaping stone, but the physics of how stone shaping works stays the same.

Incorrect chisel use; the blade isn’t in full contact with the stone. This will cause unpredictable breaks and damage the chisel.

Incorrect use of a trimming hammer; the blade is only for splitting. Don’t attempt to “chop” stone like wood.

Correct use of a trimming hammer, slightly tilted to hit on the inner edge and shear through the stone.

One of the best ways to advance your knowledge of shaping stone is to take a hands-on course. Courses offered by The Stone Trust will allow you to gain hands-on experience with a wide array of tools and stone types. Many additional courses are available to show you how to build with the stones you shape.

Hitting on a corner of the blade will cause unpredictable breaks and can damage the hammer. The blade of the hammer should make full contact with the stone.

When trimming a stone, the break will tend to spall toward the edge.

This can be limited by tilting the hammer angle toward the center of the stone, as correctly shown here. The extent of the angle should depend on the stone type, thickness, and distance from the edge.

The angle of the tip of the tool you use and the angle at which it strikes the stone will have a dramatic effect on whether the stone breaks as you intend. When you strike stone directly with a hammer, the angle of the swing will also affect the break. In general, when trimming with chisels or Trow & Holden (T&H) Stone Busters, the tool should be angled in toward the center of the stone to drive the break in and prevent “spalling,” or unintentional breaks.

When you’re removing a high spot, the point or directional point should be held close to perpendicular; 60 to 85 degrees is a sufficient angle.

Successfully shaping stone is fun and satisfying, but, like any activity, it has its own set of risks. The list below isn’t meant to be exhaustive, but covers some important points:

Brian Post is a Certified Master Craftsman, examiner, and instructor with the Dry Stone Walling Association of Great Britain. He’s also a licensed landscape architect, the executive director of The Stone Trust, and the owner of Standing Stone LLC, a company specializing in stonework.

With this book and some imagination anyone can build a beautiful stone wall. How to Build Dry-Stacked Stone Walls shows how to build a wall using the traditional method of dry stone masonry, in which carefully selected stones are properly stacked and held together without mortar. As well as being beautiful, a dry stone wall is stronger, more stable, and more resistant to climate than a mortared wall. The book features more than 100 full-color photographs of walls, bridges, and decorative garden elements in various steps of construction, as well as illustrations that show the steps and cross sections that illustrate the building methods.With dedication to the task and the author’s experienced guidance, the only limit is imagination.

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