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Slate is an attractive stone material with numerous beneficial physical characteristics, and it is also relatively easy to cut with a wide range of tools. The aim is to cut the stone accurately without splitting or chipping it. So, what do you need to know if you want to cut slate successfully?
Contents
How Do You Cut Slate?
Cut through thin slate manually by scoring the underside of the stone and cutting it with a slate cutter, or with a chisel and hammer (alternatively you can break the slate along the scored line). A high-quality angle grinder or circular saw is optimal for cutting stones and thick (more than 1 inch) pieces of slate.
Method 1: Slate Cutter
A slate cutter is a specialized tool ideal for manually cutting thin pieces of this type of stone (like slate roof tiles). Like the tile cutter in cutting tiles, this tool is intended for slate.
The most common and affordable slate cutters are hand-held and resemble giant scissors with short, wide blades.
It is worth mentioning there is also a free-standing type of slate cutter called a guillotine. Slate guillotines are larger and more expensive than hand-held models and are typically used by professionals.
Step 1: Measure And Mark The Cut Line
Measure the slate (with a rule or tape measure).
Mark the stone with the intended cut line, using a ruler or straight piece of wood as a guide. You can mark the slate with a pencil, a China marker, or a grease pen. A chisel or any other hard, sharp tool edge also works effectively and conveniently for marking slate.
Step 2: Cut Along The Marked Line
If you have a hand-held slate cutter, hold the slate workpiece in one hand if it is lightweight enough, or rest heavier pieces on a stable surface (ensuring one side is slightly overhanging).
Cut the workpiece slowly, working the tool’s scissor-like blades to slice neatly without chipping the edges of the stone. Thin slate is easy to cut with one hand, but you might need to hold the slate cutters with both hands when cutting thicker pieces.
When using the guillotine-style slate cutter, position the stone facing downward, directly underneath the blade. While holding the workpiece firmly in one hand, pull the blade handle downward to cut along the marked line.
Method 2: Chisel
Chisels are convenient tools for cutting slate. There are several ways to employ a chisel to cut this versatile sedimentary stone.
Step 1: Measure And Mark The Stone
Take measurements (if necessary), then mark the intended cut. The corner of the chisel blade works well for scratching a line on the stone.
It is preferable to draw on the underside of the workpiece since that is the side you should cut into (see below).
Step 2: Score
Score the slate by dragging the corner of the chisel blade along the marked line, pressing the tool against a ruler or guide board as you drag it.
Step 3: Wear Protective Gear
It is prudent to wear protective goggles before proceeding, as there is a chance that tiny fragments of slate that might fly into your eyes while cutting with the chisel.
Step 4: Cut The Slate
After scoring the stone, you can cut it with a chisel and hammer. The technique is simple. Hammer the chisel blade into the scored groove on the underside of the workpiece until it chips through the stone. Then repeat the process along the length of the scored line until the workpiece is cut in two.
The benefit of cutting into the underside is that it promotes the creation of tiny cracks on the visible top side of the piece – a technique called spelching. Spelching enhances the beauty of the slate’s natural foliation (thin horizontal layering), producing a more aesthetically-pleasing result.
If the slate workpiece is thin (like roof tile), an alternative option is to cut the slate by snapping it.
Place the workpiece on a solid surface. Align the scored line with the edge of the surface, with the off-cut side of the tile hanging over the side. Hold the slate firmly and snap it along the scored groove in a quick, powerful downward motion.
Instead of snapping the tile, you could use the hammer to chip off the overhanging side, using the score line to create a straight edge.
You could also perform this technique with a hammer and bench iron. A bench iron is a horizontal, upward-facing blade with two sharp, pointed sides hammered downward into a large piece of wood. The slate gets laid on the blade (aligned to the scored line), and a hammer is used to chip the overhanging side away.
Method 3: Power Saws
Power tools cut through slate easily and quickly, making them optimal for cutting thicker pieces of this attractive, fine-grained stone. Several types of power saws work effectively for this task:
- Angle grinder
- Circular saw
- Masonry saw
- Tile saw
Angle grinders and circular saws are usually convenient options since they are portable, commonly-available tools many people have access to. DIY enthusiasts often use circular saws to cut concrete blocks, wood, and other materials partnered with a circular saw guide to ensure straight cuts.
Masonry and tile saws are for cutting stone materials. These saws are available in mounted and hand-held versions. You can also choose between dry and wet masonry and tile saw models, both of which are suitable for cutting slate.
If you have a thick block of slate, then a masonry saw is preferable because the tool can make deep cuts. A tile saw, in contrast, is suited for cutting thin slate pieces (such as tiles). You can also use a tile saw to cut porcelain without breaking it.
| Power Saws | When to use |
|---|---|
| Angle grinder | Recommended in cutting thin slate |
| Circular saw | Helpful in cutting slate anywhere due to it’s portability |
| Masonry saw | Ideal for cutting thick blocks of slate |
| Tile saw | Has mounted and hand-held versions efficient in cutting stone materials other than slate |
Choosing the correct circular saw blade (called a cutting disk) is essential when using a power saw to cut slate. The cutting disk should be:
- thin
- fine-toothed
- diamond-edged (carbide disks also excellent for cutting stone)
Step 1: Measure And Mark The Slate
Measure and mark the underside of the workpiece (as described earlier).
Step 2: Position The Piece Of Slate
If you have a mounted masonry or tile saw, place the slate on the tool’s bench, with the underside facing opposite the direction of the blade’s cutting motion.
In the case of hand-held power saws, position the stone on a work table or solid, stable surface. You can use clamps to secure thin slate tiles and slabs (but this is optional).
Orient the slate with its underside facing opposite the saw blade’s rotation. The blade teeth should enter the bottom side to achieve the neatest results. For example, if you have a cordless circular saw, position the underside of the stone facing downward because the tool’s blade rotates upward (when viewed from above).
Step 3: Put On Protective Gear
Put on safety goggles to protect your eyes from the potential risk posed by flying stone fragments. It is also advisable to wear a mask to avoid breathing the copious amounts of dust that power saws produce.
Step 4: Make The Cut
Cut into the stone along the marked line. Of course, the specific technique will depend on the type of power saw and whether it is mounted or hand-held.
Always apply gentle pressure when cutting – do not force the blade through the slate. Applying excessive pressure increases the chances of chipping or splitting the stone (and it is unnecessary since the slate is so soft).
When using a hand-held circular saw or angle grinder, it is highly beneficial to move the blade up and down in a steady motion as you cut. This technique helps to produce a cleaner cut while also preventing dust build-up.
If you are working with rectangular slate tiles or slabs and need to cut diagonally across the piece, make sure to cut from the long to the short side (and not vice versa). Cutting in this direction reduces the probability of cracking the stone.
Step 5: Finish The Edge (Optional)
Power saws leave a neat, straight-cut edge that can detract somewhat from the natural beauty of slate’s riven patterning. As a finishing step, you can hit a hammer along the newly-cut edge of the workpiece to recreate and accentuate this riven look and feel.
Frequently Asked Questions
Do I Need A Wet Saw To Cut Slate?
You do not need a wet saw to cut slate. A dry saw is equally effective. The benefit of a wet saw is that the water helps reduce friction between the blade and stone, while minimizing the amount of dust in the air.
Can You Cut Slate With A Jig Saw?
You can cut thin pieces of slate with a jig saw, provided you fit the tool with a diamond blade. It is inadvisable, however, to attempt to cut thick slate slabs with a jig saw.
Conclusion
Slate is simple to cut using specialized slate cutters or with more generic tools like hammers and stone chisels. One can also cut slate using power saws fitted with diamond or carbide blades, such as angle grinders, circular saws, masonry saws, and tile saws.
