Weekend Projects - Incised slate panel archive

Friday 4 November 2016

Steve Bisco shows us how to carve a beautiful Art Nouveau ‘line drawing’ in slate

Carving an incised pattern in slate is an enjoyable stone carving project whether you are a beginner or have some experience. You don’t have to rough out or shape the stone – just patiently and gently chip out the incisions in the flat surface with just a few chisels and a ‘dummy’ mallet.  
You will often see projects based on incised lettering, but for something different I’m going to show you a large and pretty ‘line drawing’ in the style of late-Victorian illustrator Aubrey Beardsley. The plant swirls are adapted from a Beardsley book design, the peacock is one I drew myself in the Beardsley style to fit the composition and I’ve arranged the design to work as an incised pattern. It may look more complex than incised lettering, but the process is just the same.
Slate is a metamorphic sedimentary rock formed from layers of very fine silt built up and compressed over millions of years by geological activity. The layers can be split apart by ‘riving’, or ‘cleaving’ with a bolster, but the ease of delamination which is helpful in producing roofing slates can be unhelpful when carving. The thin layers can have a tendency to flake away at the edges of your cuts, which you have to manage by keeping your chisels sharp and with the edge presented at an angle of about 45°. Delamination aside, slate is a good material for incised carving. Its fine texture gives sharp detail and the lighter grey of the cut stone will usually contrast with the darker grey of the surface, making the pattern stand out.  
I have used ‘riven’ slate which has the natural matte finish left by the splitting, or ‘riving’ process but you can if you wish use smooth ‘polished’ slate instead.  

Tools used:
• 655g dummy mallet
• 6mm chisel
• 13mm chisel
• 20mm chisel

• A piece of riven slate – 540 x 270 x 30mm – weight around 13kg

Working from the pattern
This drawing shows the pattern on a grid which equates to 25mm when blown up to full size.  Ideally, make a digital copy on your computer using either a scanner or a digital camera.  Crop it into three overlapping sections of 11 squares across by eight squares down, print it out on A4 ‘landscape’ pages and it should come out full size.  Make sure all the pages have the same 25mm scale and stick them together to make the panel 540mm long. I have designed this panel so the length is twice the width, which is an easy proportion to replicate if you want to make it bigger or smaller. Just remember that if you make the panel smaller the pattern lines will get proportionally narrower.

The ‘Beardsley line’
Aubrey Vincent Beardsley – 1872-1898 – was a late-Victorian artist and illustrator whose work influenced the Art Nouveau style. Some of the content was considered risqué, but his talent was striking and unmistakeable. Tuberculosis condemned him to a short and challenging life and his large output of illustrations was produced in just six years before his death at the age
of 26. Much of his best illustration was done for the works of Oscar Wilde.
He developed a highly original and distinctive style of black-and-white line drawing in ink that was greatly influenced by Japanese art. Its distinctive feature became known as the ‘Beardsley line’ – long flowing slender curving lines creating forms and figures with a pronounced vertical exaggeration. Figures with wide skirts and cloaks at the bottom tapered upwards towards small heads, making his illustrations seem taller and narrower than they actually were. The peacock was a favourite motif.

Sharpening chisels

Slate is a silica stone and will blunt your tools as you work. They need to be sharp to cut through the slate layers cleanly, so sharpen them frequently on a carborundum stone.  Put some oil on the stone, present the cutting edge at an angle of 30° to the stone and push it along the same as you would a woodworking chisel.

Sourcing slate
The best place to look for good quality slate is at the yard of an architectural stonemason, or at makers of kitchen worktops and floor slabs. Look on the internet for your nearest supplier. Slabs about 30mm thick are good for incised panels. You can buy ‘riven’ slate, which has its natural unpolished surface, or you can buy smooth polished slate.

Working safely with slate
• Repeated exposure to silica dust can lead to respiratory illness, so work outside if possible and wear a dust mask
if you are indoors or using power tools.
• Slate chippings are sharp, so wear eye protection.
• Stone is heavy, so take care when lifting and don’t drop it on your hands or feet.

STEP 1: Get a slab of slate 540 x 270 x 30mm, or any suitable size where the length is twice the width. This will weigh about 13kg so take appropriate care with lifting. Make a full-size copy of the drawing and get some carbon paper

STEP 2: Make sure the slate is dry and free of dust. Tape the drawing securely onto the slate with the carbon paper under it and trace the pattern

STEP 3: You will need a ‘dummy’ mallet and three chisels in widths of 6mm, 13mm and 20mm. Make sure the chisels are sharp. Put a ‘softener’ such as a cork mat on the bench so stone chips that get under the slate don’t create a pressure point that could fracture the slab. The pattern tends to become a bit faint as you carve, so scratch in the carbon lines with a sharp point before carving

STEP 4: Start by taking a 6mm chisel and cutting a line along the centre of one of the wider stems. Place the chisel with the cutting edge at an angle of about 45°, so just one of the corner points is digging in. Lay the shaft back also by about 45° and gently tap the chisel with the dummy mallet. Aim to drive the chisel along by about 2mm with each tap, keeping up a steady rhythm. Steer the chisel midway between the guide lines and try to create fine powder rather than chips

STEP 5: After the first cut, turn the chisel over and carve along the other side of the cut  

STEP 6: Keep repeating this process and gradually widen the cut until you reach the guide lines. Keep the chisel angle the same on both sides so the ‘V’ of the incision is about 90° at the bottom and is sharp and regular

STEP 7: The depth of the ‘V’ will increase in proportion to the width of the line, so in the wider parts you will need to switch to a 13mm chisel, otherwise the uppermost point of your chisel will be below the surface of the slate and may lift the edges

STEP 8: Continue this process up the curly stems. Some of the smaller stems are very narrow, so go carefully and take care to steer the chisel around the pretty swirls without putting kinks in the curves. Where the lines cross, follow each line through so its ‘V trench’ cuts across the other line without losing direction or width. Try to get sharp mitres in the ‘trench’ where the incisions meet and note that narrow lines will not be as deep as the wider lines in the crossover

STEP 9: As you work towards the bottom end the stems get wider and you will need to use the 13mm chisel more

STEP 10: Along the stems there are several ‘husks’ from which the upper stems emerge. These need a little ‘sculpting’ inside the incision to create a sharp ‘ridge’ between the husk and the stem above, by carving the ‘V’ of the stem along the edge of the ‘V’ at the top of the husk. To carve the fine points at the outer tips of the husk, place the point of the chisel on the tip of the husk and carve inwards, then widen the line as you move away from the tip

STEP 11: In the bottom left corner there is a large husk from which the whole plant emerges. This is quite deep and is close to the corner, so over-zealous chiselling could break off the corner. Just chip along gently, working inwards from the corner

STEP 12: Finish the plant by carving the thin swirls that run from left to right across the bottom. Take care not to put any jarring kinks in the large graceful curves. The peacock pattern is hidden under the dust where I scratched it in, so it is worth hosing it down at this stage

STEP 13: Start the peacock by carving the long slender neck, which starts in a point at the bottom then tapers up towards the head

STEP 14: Carefully shape the head with its narrow neck and pointed beak. The eye needs particular care – carve away both sides of it until just a point remains at the top. The three plumes must be carved very thin – the tiny roundels at the top ends are made by placing the chisel point in the middle, then walking round in a circle while gently chipping into the centre

STEP 15: The peacock’s body and tail feathers are depicted by 14 swirls to represent the ‘eyes’ on the feathers. Five of these swirls are formed by thin curly lines with the ‘circle’ end open

STEP 16: The other nine swirls have large roundels at the lower end, for which you will need to use a 20mm chisel. Place one point of the chisel into the centre of the roundel and keep chipping into it as you turn around the circle – it really helps if you can walk right round your bench for this. Cut at a slightly shallower angle or it will get very deep in the centre

STEP 17: To finish off the panel, mark a line 3mm in and down from the outer edges and cut a chamfer along all sides

STEP 18: Now wash off the dust and display the panel where the light will strike it obliquely to enhance the shadows. Slate is impervious to water and it will live happily outdoors or indoors

Top tips
1. If stone chips get under the slate while carving they can create a pressure point that may fracture the slab. Use a ‘softener’ such as a cork mat on the bench to avoid this and make sure your bench surface is dead flat
2. When carving curly lines it helps to have a freestanding bench that you can walk around, so you can navigate the curves without having to keep repositioning the work  
3. Smooth away the tool marks after you have finished a cut by pushing the chisel along the cut


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