THE MAKING OF A BRONZE 'SKULLPTURE'

skullpture series - main page

Stages in the making of 'Skullpture

1. The original skull. The natural holes have been filled with Chavant clay to prevent the intrusion of silicone into the skull.The skull has been affixed to the board with screws. 2. I have determined a centre line for the two-piece mold and have begun to build up around the base, in order to create the mold for the top half. Note the use of styrofoam and synthetic clay. If you look carefully, you can see the pencil mark used to determine the centre line.

3. The clay is built up to the half way point on the skull and smoothed out. Another view. 4. Duct Tape or Saran Wrap is placed over the skull to protect it during the next phase.

Another view. 5. I have begun to add another 3/8" layer of clay over the skull to create a space for the latex, once the fibreglass shell is created. Another view. Note, this second layer of clay covers the skull only and does not extend onto the original 'flange' of clay.

The second layer of clay is complete. Another view. 6. A release agent is painted on prior to adding the fibreglass. In this case it is axle grease cut with thinner!

7. I am painting on a mizture of 4 parts Bondo (with 1" hardener) to one part resin (with one squeeze of hardener, mixed first). Another view.Be careful not to get this stuff on the styrofoam, as it dissolved readily! Complete and allowed to harden.

8. Layer resin and fibreglass. Tear the fibreglass matt and touch to the resin... ... then tamp in with a brush and resin. 9. Add an extra layer of matt and resin around the flange for additional support.

Another view. 10. When hardened and dry, remove the fibreglass from the sculpture, after drilling reference holes around the flange. Insert screws into the reference holes in the clay. 11. Clean out the filler clay, repair the flange, spray the entire sculpture and fringe with release, then add a silicone bead around the inner portion of the flange...

... Drill a hole in the highest point of the fibreglass shell and reattach to the sculpture and flange, using reference points. Pour in silicone mold compound slowly, to allow air to escape. 12. Take the lower portion of the mold off, turn the sculpture, silicone and fibreglass over and repeat the previous steps to make the second half of the mold and shell. Another view.

Repeat of steps 4-10.Note that once the second fibreglass shell is complete, holes are drilled through both flanges and bolts with wing nuts are inserted. Use a grinder or sawsall to trim the rough fibreglass edge. When trimming the molds with the sawsall and grinder, make sure that separation of the molds is achieved. Though the fibreglass will bind on the edges, it should not have bound on the surface treated with the grease. Repeat of step 11. Note that there were two high points on this side. Two holes were drilled. When the lower high point filled, it was covered with clay, to allow the rest of the mold to fill.

Another view. Gently pry the mold apart after allowing hte silicone to set fully. Another view.

Separate the silicone from the original. Another view. 12. Wax has been poured into the two halves of the mold to test the quality of the mold.

The first wax impression from this mold! 13. The two halves have been trimmed and assembled. Though the cast version will use a single wax taken from the attached mold, this give some impression of the wax prior to casting. Another view.

14. This is a pic of the wolverine and seal skulls as they are being sprued up with wax rods. The intention is to create a path for the bronze to enter the sculptures and to allow air and bronze to escape, filling the sculpture completely with bronze. 15. After spruing, the entire assembly is dipped in a cement-like slurry, then covered in fine silica sand. 16. It is then placed on a wire shelf and allowed to dry throuroughly (2 hours). Air tubes are inserted to allow inner surfaces an equal chance to dry.

17. The sculpture is dipped thirteen times and covered in courser grades of sand. This pic shows the wolverine/seal assembly in an early stage of dipping, and the grizzly skull after its final dip. 18. Once dry, the shell is drilled from the end opposite the end that will receive the bronze. It is then turned upsidedown in a kiln and the wax is melted out of the shell, as the shell is cured. 19. The cured shell is allowed to cool, then inspected for cracks. The drill hole is patched and the cracks are repaired with a special cement.

20. The bronze furnace is heated. Note the piece of bronze on the lid, which is 'drying' prior to insertion in the crucible. 21. As the bronze is heating, the ceramic shells are replaced in the kiln and heated/dried prior to the pour. This is necessary to avoid cracking or an explosion, due to the shock of hot bronze contacting a cold shell and or moisture. 22. The final piece of bronze is melted.

23. The HOT shells are secured by chains in the sandpit. Note the protective clothing and gear. A close up of the secured, hot, ceramic shells. 24. Once the bronze is brought up to the right temperature, the crucible, containing the molten bronze, is removed with a large pair of tongs, operated by two people.

25. The crucible is placed in the carrying device ... 26. ... which allows the handlers to pour the bronze. 27. Once the metal has cooled sufficiently, it is removed to another work area, preferably outside!

Another view. 28. I am using a sledge hammer to loosen the shell from the bronze. The bronze appears!

29. The remainder of the shell is removed using and air point chisel, and hand chisels. The inner surfaces are particularly challenging to free of shell. The freed bronze, with sprues still attached.

30. The sprues have been cut off with a torch and/or hacksaw. Any cracks or holes have been filled with a welder using bronze rods. The irregularities have been 'chased' or ground smooth, using burrs and air tools. Then the whole bronze has been sandblasted to create an even surface prior to carving. 31. The designs for each carving are drawn directly onto the raw bronze prior to carving. 32. Using power grinders and carbide burrs, designed for metal work, the designs are carved and the bases are completed using black granite. Following the carving the surface is smoothed with sandpaper, depending on the kind of patination to be applied.

33. Prior to patination, it is important to clean the surface of the bronze, to remove impurities and any surface oxidation. The most effective way to do this is to sandblast the surface with a fine grit sand. It is important to avoid touching the surface of the bronze with bare hands after this process, as it will pick up oils and create uneven application/oxidization of the patina.

34. The next stage is to apply the base coat, which in this case is an application of Birchwood Casey applied cold and then rinsed. An alternative base coat would be liver of sulphur, also applied cold. Following the rinsing, the bronze is heated to set the base coat and then the whole is rubbed back with steel wool.

35. Finally it is time to apply the patina! There are numerous oxidizing agents available for patination, all lending a unique look and colour to the bronze. I have chosen to use bismuth nitrate (with varying additions of titanium oxide) and silver nitrate for the human skull and some accents on other pieces (eg. wolverine). The patina is also applied by brush, lending a unique, ringed pattern to the finish. The patina is applied to a hot bronze surface, made so with an open flamed torch. Following the application the entire surface is quenched in water and reheated to dry the bronze and set the patina. The pic below show the patination set up and a variety of pieces in various stages of completion. Note the patina seems much whiter than it will appear after the final coat of lacquer is applied.

36. The patina is fragile and needs to be protected by a couple of coats of lacquer. Since the lacquer lends a plastic look to surface, two coats of Trewax are applied and buffed to dull the surface down and provide additional protection. Voila, the finished bronzes!

skullpture series - main page

1. The original skull. The natural holes have been filled with Chavant clay to prevent the intrusion of silicone into the skull.The skull has been affixed to the board with screws.	2. I have determined a centre line for the two-piece mold and have begun to build up around the base, in order to create the mold for the top half.	Note the use of styrofoam and synthetic clay. If you look carefully, you can see the pencil mark used to determine the centre line.

3. The clay is built up to the half way point on the skull and smoothed out.	Another view.	4. Duct Tape or Saran Wrap is placed over the skull to protect it during the next phase.

Another view.	5. I have begun to add another 3/8" layer of clay over the skull to create a space for the latex, once the fibreglass shell is created.	Another view. Note, this second layer of clay covers the skull only and does not extend onto the original 'flange' of clay.

The second layer of clay is complete.	Another view.	6. A release agent is painted on prior to adding the fibreglass. In this case it is axle grease cut with thinner!

7. I am painting on a mizture of 4 parts Bondo (with 1" hardener) to one part resin (with one squeeze of hardener, mixed first).	Another view.Be careful not to get this stuff on the styrofoam, as it dissolved readily!	Complete and allowed to harden.

8. Layer resin and fibreglass. Tear the fibreglass matt and touch to the resin...	... then tamp in with a brush and resin.	9. Add an extra layer of matt and resin around the flange for additional support.

Another view.	10. When hardened and dry, remove the fibreglass from the sculpture, after drilling reference holes around the flange. Insert screws into the reference holes in the clay.	11. Clean out the filler clay, repair the flange, spray the entire sculpture and fringe with release, then add a silicone bead around the inner portion of the flange...

... Drill a hole in the highest point of the fibreglass shell and reattach to the sculpture and flange, using reference points. Pour in silicone mold compound slowly, to allow air to escape.	12. Take the lower portion of the mold off, turn the sculpture, silicone and fibreglass over and repeat the previous steps to make the second half of the mold and shell.	Another view.

Repeat of steps 4-10.Note that once the second fibreglass shell is complete, holes are drilled through both flanges and bolts with wing nuts are inserted. Use a grinder or sawsall to trim the rough fibreglass edge.	When trimming the molds with the sawsall and grinder, make sure that separation of the molds is achieved. Though the fibreglass will bind on the edges, it should not have bound on the surface treated with the grease.	Repeat of step 11. Note that there were two high points on this side. Two holes were drilled. When the lower high point filled, it was covered with clay, to allow the rest of the mold to fill.

Another view.	Gently pry the mold apart after allowing hte silicone to set fully.	Another view.

Separate the silicone from the original.	Another view.	12. Wax has been poured into the two halves of the mold to test the quality of the mold.

The first wax impression from this mold!	13. The two halves have been trimmed and assembled. Though the cast version will use a single wax taken from the attached mold, this give some impression of the wax prior to casting.	Another view.

14. This is a pic of the wolverine and seal skulls as they are being sprued up with wax rods. The intention is to create a path for the bronze to enter the sculptures and to allow air and bronze to escape, filling the sculpture completely with bronze.	15. After spruing, the entire assembly is dipped in a cement-like slurry, then covered in fine silica sand.	16. It is then placed on a wire shelf and allowed to dry throuroughly (2 hours). Air tubes are inserted to allow inner surfaces an equal chance to dry.

17. The sculpture is dipped thirteen times and covered in courser grades of sand. This pic shows the wolverine/seal assembly in an early stage of dipping, and the grizzly skull after its final dip.	18. Once dry, the shell is drilled from the end opposite the end that will receive the bronze. It is then turned upsidedown in a kiln and the wax is melted out of the shell, as the shell is cured.	19. The cured shell is allowed to cool, then inspected for cracks. The drill hole is patched and the cracks are repaired with a special cement.

20. The bronze furnace is heated. Note the piece of bronze on the lid, which is 'drying' prior to insertion in the crucible.	21. As the bronze is heating, the ceramic shells are replaced in the kiln and heated/dried prior to the pour. This is necessary to avoid cracking or an explosion, due to the shock of hot bronze contacting a cold shell and or moisture.	22. The final piece of bronze is melted.

23. The HOT shells are secured by chains in the sandpit. Note the protective clothing and gear.	A close up of the secured, hot, ceramic shells.	24. Once the bronze is brought up to the right temperature, the crucible, containing the molten bronze, is removed with a large pair of tongs, operated by two people.

25. The crucible is placed in the carrying device ...	26. ... which allows the handlers to pour the bronze.	27. Once the metal has cooled sufficiently, it is removed to another work area, preferably outside!

Another view.	28. I am using a sledge hammer to loosen the shell from the bronze.	The bronze appears!

29. The remainder of the shell is removed using and air point chisel, and hand chisels.	The inner surfaces are particularly challenging to free of shell.	The freed bronze, with sprues still attached.

30. The sprues have been cut off with a torch and/or hacksaw. Any cracks or holes have been filled with a welder using bronze rods. The irregularities have been 'chased' or ground smooth, using burrs and air tools. Then the whole bronze has been sandblasted to create an even surface prior to carving.	31. The designs for each carving are drawn directly onto the raw bronze prior to carving.	32. Using power grinders and carbide burrs, designed for metal work, the designs are carved and the bases are completed using black granite. Following the carving the surface is smoothed with sandpaper, depending on the kind of patination to be applied.