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How to Carve a Clamshell

Andrew Thomas shows how to carve your own wonderful, decorative seashore shell.

Ever since I was a child, I have enjoyed walking along the seashore and studying nature’s wonders, be they interesting pieces of driftwood, beautifully sculpted pebbles or the amazing selection of shells in all shapes, sizes, textures and colours. These natural forms fascinate me and have inspired many sketches over time that consequently develop into my own living works of art. The clamshell is one of these inspirational forms and the base for this study and project, which has been abstracted from its real-life detail to produce a very fine finish with gentle, flowing curves across its surface. These undulations interact beautifully with the shadow to create a subtle but effective feel of depth, that in turn enhances the natural appearance of surface tension in the medium and composition.

There are many ways in which this project can be adapted to suit the reader’s own design ideas. One thought to consider is adding to the surface textured effects which can be found naturally on the surface shells of clams, cockles, scallops and many other shellfish. Either way, it is highly recommended to source some real-life examples to study and work with that will facilitate a greater understanding and feel for the shape of the form, and the desired finish. Before you start working on the project, please read through the complete step guide and study the stage and finished images to see how the sculpture develops.

Did you know?

The great British sculptor Henry Moore had a vast collection of seashells, stones, pebbles, flints and bones, among other natural forms, which inspired many of his magnificent works across the decades. These organic forms are an ideal resource from which a multitude of design ideas can be developed to produce outstandingly elegant sculptures in the medium of wood, which lends itself beautifully and naturally to the subject.

Things you will need

Tools

  • The sizing of the following tools is for Swiss gouges
  • No.2, 5mm
  • No.2,10mm
  • No.2, 20mm
  • No.2, 40mm
  • No.5, 20mm
  • No.8, 4mm
  • No.8, 7mm
  • No.8, 10mm
  • No.8, 13mm
  • No.8, 16mm
  • No.8, 18mm
  • No.11, 4mm
  • No.12, 6mm
  • No.16, 3mm
  • Knife
  • Saw

Materials

  • Timber: American black walnut (Juglans nigra) 180 x 160 x 75mm
  • Boiled linseed oil
  • Medium brown wax

Clam shell plan

Drawings and how to resize them

To enlarge or reduce the size of drawings right click on the image to download it and then go HERE to watch a video on how to use paper with a grid to do exactly that.

1. Copy the scale drawings provided, enlarging them to the size for your wood, and print them out on to card to use as a template and reference. Transfer either the upper or lower design on to your block of wood, with the grain direction running vertically through the block. Ensure that there is a spare section of wood underneath the form, with a minimum length of 30mm that will be used to attach it securely to your vice. Cut out the design then measure and draw centrelines on the face of the wood, front and back, and along the complete edge. Transfer the side view profile drawing on to both profile edges by sighting the design squarely in position
2. The first areas of waste wood to remove are the top sections on both the upper and lower sides of the form. Use a No.2, 20mm to pare the wood down to the depth of the design line on either edge, then work this depth neatly across the surface to the opposite edge. Repeat this procedure on the opposite side
3. To simplify the shaping of the profile along the lower edge, use a saw to cut inwards underneath the design. Measure 15mm outwards from both sides of the centreline on both edges of the form and mark these positions on your wood. Use a saw to cut underneath the form until you reach these 15mm positions
4. Now use the No.2, 20mm to pare the wood away along the design line, down to meet the depth of the saw cuts
TOP TIP

To verify that the depth of the surface is level from one side to the other, use either a try square or the edge of a steel rule. This will clearly define any areas of the surface that are proud and need a little more work.

5. With the side view profile carved, the next job is to carve the natural shape of the clamshell across both upper and lower sides of the form. The most efficient tool to use for this job is a No.2, 40mm, but a smaller-width gouge will also work. Starting at the middle of the arc, pare away the waste wood on both sides to form a gentle curve, from the centreline on the face to the centreline on the edge
6. Continue to shape of the surface from the centre of the arc downwards to the base. The shaping of the lower edge at the very base will not be possible until the end when the form is cut off the mount
7. The markings shown on the wood delineate the proportion of the shell where it naturally protrudes strongest. This dictates that the areas on the outside of these lines need to be pared back slightly to enhance this visual effect of the central bulging mass on the surface. Use your template to help you draw these lines in position. Then use a No.5, 20mm to carve from the lines across the grain towards the edge. Repeat this on both sides
8. This side view gives a clearer understanding of how much wood to remove in step 7
9. The sharp angle between the central protuberance and the adjoining sides that were carved in step 7 can now be blended naturally together, forming a gentle unity of surface depth that flows seamlessly across it. Do this using the large No.2 gouge
10. The section at the very top of the form will also require blending into the surrounding areas to create the basic form into which the deep grooves will be carved in step 14
11. Next, we move to the lower position of the edges, where the objective is to produce a tight crease, which will eventually flow from side to side when the lower edge that is attached to the base is finished. Measure 35mm up from the base and mark this position on both edges of the clamshell. Use a No.16, 3mm V-tool to carve a deep channel from the 35mm mark down to the base. Repeat on the opposite side
12. Now use a No.2/5mm gouge to curve the adjacent edge into the V-tool cut. Repeat steps 11 and 12 again, tapering the groove out wider as it flows down to the base
13. Finally, use a razor-sharp knife to make a deep slice into the V-tool channel, and the No.2/5mm again to curve the edge into the knife cut, creating the natural-looking tight crease. This should now be at least 3mm deep at the lowest position and hold a good amount of shadow. Check to verify this and make further adjustments if necessary. The very lowest edge will be completed when the clamshell is cut off the base
TOP TIP

The knife is without doubt one of the most dangerous tools to use due to it being prone to slipping. Therefore, great care must be taken when using this highly versatile and valuable tool. Rule number one: never cut towards any part of your body. Rule number two: make sure that it is razor sharp and always stropped before use. Rule number three: keep the handle at a low cutting angle, especially when working over raised contours, to ensure that it does not slip.

14. The next job is to carve the deep channels in their correct order across both the upper and lower faces of the clamshell. Using the templates provided to assist you, measure and draw each of the grooves in their correct position on the surface of the upper and lower faces. Please note that these grooves are staggered opposite one another on each side of the shell. Use a selection of No.8 gouges, from 4mm at the base up to 18mm at the top, to create these grooves
15. The finished depth of each groove should be approximately the same across the shell, which can be made deeper if the reader wishes
16. Repeat step 14 on the opposite side, carving each groove in harmony of curvature and depth with its opposite one
17. The convex curves in between the grooves are next to be shaped. Use the No.2, 20mm held upside down, which naturally lends its sweep to the contour of the detail, working from the centre of each section, into its adjacent groove. As you work down towards the base, swap to a No.2, 10mm
18. You may find that you have to swap between the No.8s and No.2s to achieve an even balance across each section at the top end. This will be a focal point when the piece is finished, so it’s important to ensure that this is accomplished as evenly as possible

At this stage

At this stage of the carving, the reader can, if they wish, add other details to the clamshell in the form of texture, a series of vertical lines, a series of curved horizontal lines, or anything that they feel would add to the composition and overall aesthetics of the finished piece.

19. Before the clamshell is cut off the base, it can be sanded through all the abrasive grits to blend the surface naturally and evenly together. Start with grit 100 to completely remove all tool marks. As you work down towards the base, use a small piece of dowel to brace the abrasive in the tighter grooves
20. Dust off the wood then brush or pour hot water over the shell and leave it to dry. Next, work through grits 150, 240 and 400, removing all the scratches from each previous grit and repeating the hot water process in between. When you are sure that the abrasive work is completed to a fine finish, use the saw to cut the clamshell off the base
21. You now need to finish off the tight crease that flows from side to side, shape the lower edge and extend the grooved channels. To do this, draw a line to connect the two creases on the edges together that were created in steps 11-13 and use a 6mm V-tool to carve a deep channel along this line to join these edges
22. Use the No.2, 10mm to shape the sawn wood at the base naturally into the V-tool groove. Then, swap the V-tool for the No.16, 3mm, and use this to cut a deeper, tighter channel. Repeat steps 21 and 22 until the shape of the lower edge corresponds with the side view profile design
23. Use the razor-sharp knife again to make a deep slice into the V-tool channel, and then the No.2, 5mm to curve the lower edge into the knife cut to create the desired crease
24. The grooved channels on the lower edge can now be extended as close to the crease as possible. You need  to create the visual impression of tension in the material, as well as the natural form of the clamshell. It is therefore very effective to make deeper, tighter grooves in this lower area, which can be achieved using a No.11, 4mm
25. These deep-grooved edges made with the No.11/4mm will now need to be curved into their surrounding areas to produce the natural effect of them emerging from this lower edge up through the shell. Do this with the No.2, 5mm
26. Now work through each of the abrasives as outlined in steps 19 and 20, using the hot water technique in between each grit to produce a fine finish
27. The hot water technique will also raise the grain in the tight crease, which will require another slice with the knife to clear the channel, creating the infinitive crease for the shadow to fall in
28. The finish used for the example was chosen to enhance and enrich the beautiful colour tones and figure in the timber. Boiled linseed oil was initially applied over the surface of the shell, which lowers the natural colour tone of the walnut and adds to the effect of the shadow. This was left for a week or so to dry before several coats of medium-brown wax polish were applied to seal the grain and give a fine finish
29. Here is a selection of images showing the clamshell from different viewpoints. Now for a few comments regarding the presentation of the finished clamshell. There are effectively two options to present the finished piece. It can either be pinned at the base and mounted vertically on wood, stone or some other material, which will show the upper and lower sides to good effect, but cover the crease around the lower edge. Alternatively, it can be presented in its natural position on its side, without the need for any fixings, preferably on a highly reflective material, which, in my opinion, adds to the viewing experience

Further reading

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