I am going back to uni this week to start my course in Carving and Casting. This year I am planning to learn more about repeat casting units and some more advanced stone setting techniques. I hope I will be better at keeping the blog updated this time!
I thought this would be a good time to share some of what I learned last year on the course.
Cuttlefish casting is the easiest and least expensive (in terms of equipment) form of casting metal. It was the first technique we learned and is a good way of learning the principles of casting.
Here is my version of a step-by-step on how to complete a cuttlefish cast.
What you will need:
A Cuttlefish bone
Saw
Shape you wish to cast (can be made in wax, plastic, wood etc.)
Carving tools
Binding wire
Wire cutters
Casting metal (Pewter, silver etc.)
Crucible or pot to melt metal in.
Gas Torch or other heat source.
Leather Gloves
Goggles
Step-by-Step
1. Prepare the cuttlebone by removing the pointed top and bottom with a saw. Then saw it in half lengthways.
2. Make sure both halves fit together well by gently rubbing the flat sides against each other until they are flush.
3. Take the half of the cuttlebone with the harder back and begin pressing the shape to be cast into it. About 1 inch from the top of the bone. If the shape is difficult to press in, use a carving tool to remove some of the cuttlebone. Be careful not to press too hard as the cuttlebone is very brittle and may break. Alternatively a shape can be carved out of the cuttlebone directly.
4. Once you have made your impression, use a carving tool to cut a funnel from the top of the bone to your shape. This will form the button. Also remember to draw some air lines out from the shape. This will help to prevent air bubbles and ensure a more complete cast. Dust any powdery residue from the bone using a paintbrush.
5. Place the two halves back together again, making sure they fit together tightly. Then wrap securely with binding wire.
6. Stand the cuttlefish bone firmly on a heatproof surface. Heat the metal to be cast. Always make sure you have enough metal to fill you cast plus some extra for the button. Once the metal is molten, pour it into the funnel opening.
7. Leave the cuttlebone to cool before moving it. Then run it under cold water to ensure it is fully cooled.
8. Remove the binding wire using wire cutters.
9. Lift off one half of your cuttle bone and see your cast. The metal should have also filled the air lines and some of the funnel opening.
10. Lift your cast out from the cuttlebone.
11. The air lines and button can now be removed using a saw.
12. The edges can then be tidied with files and emery paper.
Please note: This technique gives the cast a flat back with a cuttlebone texture. Where the shape has been pressed, the cuttlebone layers are compressed giving a smoother finish. If the shape is carved out of the cuttlebone the layered texture is more visible.
To achieve a shaped back rather than a flat back, the other half of the cuttle bone is also carved or indented. If using a shape, place it in the cuttlebone and then put the two halves together (Before step 5). Use matchsticks or wire to pierce the cuttlebone and mark where they line up. separate the two halves and remove the shape before reassembling and continuing with step 5.
Some more notes:
If casting in silver (or gold) the cuttlebone can only be used once, whether the cast is successful or not. This is because the heat of the metal burns some of the cuttlefish when it is poured into the cast. If using pewter the cuttlebone can be used a few times if you are careful.
Cuttlebones can be bought cheaply from pet shops. The best bones to choose are large and as thick as possible. Thin small ones are more likely to break.
Sorry for the lack of photos at the beginning of the step-by-step - I only remembered to documented the process once I got home from my class and had my camera!