This heart shaped pendant first started off as a 1963 Canadian Silver Dollar. It was about 80-20 silver to copper. The rough shape was made using the lost wax technique and after hours of filing, sanding and polishing the final product was finished. It was made for my gf for our anniversary.
Step 1: Wax Shape
The wax used was from a candle from the dollar store. It was heated using hot water and formed by hand. I made it a little bigger then what I wanted the final size to be to account for any shrinking and room to file and polish. The sprue (the hole made for the metal to be poured) was made extra large to be turned into the ring so it could be hung from a chain.
Step 2: Mould
The mould was made using drywall compound. This isnt ideal but I'm a poor student and its what I had available. Plus I figured if they use it in homes it must be fire resistant as its main ingredient is limestone
I covered the wax shape with a thin layer of compound to ensure it was completely covered and any air bubbles wouldn't affect the overall shape. After it was left to dry over night, the whole thing was placed into a lager cup of drywall compound with the sprue sticking up and left for a few days to dry.
Step 3: Lost Wax
This is the lost wax part of the whole thing. I put the mould in the oven upside down so that the melted wax could run out. I set the oven at 350 F - seemed like a solid choice, thats how hot I cook lasagna... I then increased the temperature gradually to prepare it for casting. The hotter the mould the better. This way the metal isnt shocked when it hits the cold mould and the metal flows longer which increases its chances of getting in all the small spots of the mould.
I used a soup can as a crucible and melted the coin with a mapp gas torch. Mapp gas burns in air at roughly 3700 F.
Step 4: Rough Cast
After 15 mins of cooling, this is the mould broken open. The mould ended up cracking during the pre-heat which lead to its rough shape. Leaving it to air dry longer so all the moisture evaporated would probably have fixed that.
Step 5: Filing
Using a variety of files and 120 grit sand paper the heart is taking shape
Step 6: Polishing
Using finer and finer sand paper the surface was beginning to shine. After the 120 grit, I used 400 grit (the picture shown) and then straight to 1500 grit.
Step 7: Finale
After a few hours of watching tv and polishing the pendant with polishing compound and a cotton rag I got the surface to a finish I liked. I found that extra-whitening toothpaste worked better than the compound for its final shiny finish.