Gothic boss in oak

The Gothic style of the Middle Ages was one of the high points in the history of carved decoration, and this project takes us back around 800 years to the world of medieval woodcarvers whose lives were very different to our own.

This attractive boss, carved in oak (Quercus robur), is a direct copy from Pugin’s Gothic Ornament.

I haven’t been able to confirm where this boss came from, but I had a suggestion from the archaeologist at Winchester Cathedral that it could be from the medieval Palace of Westminster — the old Houses of Parliament that burnt down in 1834. We can, at least, be confident it is medieval and probably English.

A boss is a carved and decorated architectural feature at the junction of the ribs in a Gothic vaulted ceiling. In a stone roof, the boss forms a keystone where the arches of the ribs meet. In a wooden roof its function is mainly decorative. This boss is made up of three layers — Repton’s drawing helpfully shows the structure — so carving it is easier than it looks.

The medieval original would probably have been brightly painted in multicolours, but we are used to seeing ancient oak aged to a dark brown. We can create this effect by the simple process of fuming with ammonia to make our new oak look suitably ancient.

You can also, if you wish, form the outline shape of the top layer on a woodturning lathe — if you have access to one — more quickly than with carving tools alone.

Preparations

1. This carving is in three layers, each of which is 38mm thick. The base section is 356 x 356mm, the middle section 381 x 381mm, and the top section is a circle 145mm in diameter. To start this project you need to make a full-size copy of the drawing and use carbon paper to trace the patterns onto the blocks of ‘green’ oak (Quercus robur).

2. The next step is to mark your cutting lines in red to avoid making any mistakes. Drill out the holes in the leaf edges of the lower and middle sections with a 10mm drill.

3. Cut round the pattern edges with a band-saw, jigsaw or scrolisaw. If you don’t have any of these, make friends with someone who does as it is a lot of work with hand saws!

Carving the base section.

4. To carve the base section, start by cutting a cove 10mm deep with a 16mm No, 9 gouge, following the line along the rib and curving round to the ’leaf. Lower the surface behind the ‘berries’ down to this 10mm level.

5. Cut another 10mm cove around the ‘lobes’ to the ‘cusp’ behind the berries, so the bottom edge is 20mm below the top surface. Cut out the ‘eye’ behind the lower coves. Reshape the rib to create a smooth 20mm deep cove where the two 10mm coves merge.

6. Repeat the process on the remaining sections. Draw a smooth curve from each rib to within 65mm of the centre of the boss — not shown on the drawing as it is hidden — and create another ‘eye’ between the coves.

7. Lower the top surface of each berry by about 6mm and round it over into a hemisphere. Use a skew chisel to sharpen the gap between the berries.

«Use a skew chisel to sharpen the gap between the berries».

8. Lower the edges of the leaves and shape the bulge in the middle and the horseshoe ridge around it. Use a 10mm No.3 gouge to make the incised crescent cuts around the edges and in the middle. Put a crinkle in the edges to create a good Gothic look.

9. Now you need to turn the piece over and undercut the edges so the rib moulding has a fillet about 10mm wide, the leaf edges are about 13mm thick, and the berries about 20mm deep. Here, use wedges to brace the berries which have only a short-grain connection at the cusps.

10. The finished base section should look like this.

Carving the middle section

11. The middle section has shorter berry cusps than the base. Reduce the level immediately behind the berries by 10mm, reduce their tops by 6mm and round them over as before.

12. Carve this complex arrangement of coves from the berries to the ‘fleur-de-iys’ leaves, with the lower edge about 15mm below the top surface. Carefully and neatly shape the edge of the inner circle, merging it smoothly into the coves and ridges, with a little ‘eye’ behind the berries.

13. Carve the ridges and coves along the ‘fleur-de-lys’ leaves, with the points about 15mm below the original surface. Brace the two opposite arms of the ‘cross’ that flow across the grain to prevent breaking them off at the narrow short-grain section. Create a lively flow to the curves, and put a chamfer around the leaf edges. Blend the inner end of the leaf into the inner circle.

14. Turn it over and undercut as before, but with the leaf edges about 8mm thick near the ends. Brace and support the cross-grain arms while carving.

15. The finished middle section should look like this.

Carving the centre boss

16. The quickest and easiest way to form the outline shape of the centre boss is with a woodturning lathe. Mark the three concentric circles and shape the three layers that will form the basis for the carving. If you don’t have a lathe of your own, or a friend with one, form the shape by hand with chisels.

«Carve the segments into the form of a ‘ruff’, a bit like a linen fold pattern».

17. Divide the outer circle into eight equal segments of 45°. Repeat the process in the inner circle with the segments alternating to the outer circle.

18. Carve the segments into the form of a ‘ruff’, a bit like a linenfold pattern.

19. Carve the central ‘button’ into small pyramids about 13mm square, aligned diagonally to the grain direction, and the centre boss is finished.

Assembly and finishing

20. Assemble the three sections with the grain all running in the same direction. You can use glue if you make sure not to get it on the external parts — it will affect the fuming — but instead I used four long screws from behind with the heads sunk in and the holes closed with oak dowels I made on the lathe. Photos 20 and 20a show the front and side views.

21. For an authentic antique look you can darken the oak by ‘fuming’ it with ammonia. This replicates nature’s ageing process and looks more natural than stains. Make up an airtight ‘tent’ -or use a plastic tub if you can get one big enough — and place the carving in it, raised on supports such as nails. Put in about 50-80ml of household ammonia — obtainable from hardware stores — in a shallow dish — wear goggles to protect your eyes -and seal the tent or tub. Leave it until the oak darkens to a pleasing dark brown — about 6-12 hours depending on the temperature, the concentration of ammonia and the amount of tannin in the oak.

22a & 22b. The finished carving now looks like a relic from the Middle Ages. Rub it hard with a dry cloth to bring up a sheen on the surface or, if you prefer, go over it with a good wax polish -please, no varnish!

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