Intro: Make a Simple Copper Bowl
Don't you love the colour and texture of a hand-made copper bowl?
You can easily make a simple, small shallow bowl to hold change, paper clips or keys - or just to meditate on while you're on a conference call.
Step 1: Getting Organized
List of Materials & Tools:
- Copper sheet (e.g. 6" square cut out of "20 oz" sheet copper);
- Tree stump with a depression in it;
- Metal snips;
- Ball pein hammer (e.g. 12 oz size);
- Propane torch and bottle (e.g. "Tiger Torch" with (25 lb) propane bottle);
- Tongs or pliers (for handling the copper bowl when hot);
- Bucket with "pickling (acid) solution" (e.g. "Lime Away" or some other inexpensive alternative to "CLR");
- Bucket with fresh water (big enough to hold the copper bowl);
- Leather work gloves;
- (Hearing protection, respirator, fire extinguisher, other safety gear as necessary, rags, etc.);
- (Optional: compass with a pencil, to draw a 6" circle on the copper; file (e.g. flat bastard file, medium coarse) to smooth the edges of the bowl; a stiff plastic brush for cleaning the oxide loosened by the pickling solution; a lightly abrasive cleaner like baking soda; clear plastic spray finish (glossy or matte).)
Sourcing Your Materials & Tools:
Copper: your local heating and sheet metal shop/contractor; ("20 oz"
sheet copper is a nice weight to work with; you will probably be charged for the material by the pound e.g. $12-15/lb; it might come with a plastic film to protect the finish, so you can leave the film on for now);
Tools: your favourite local hardware or building supply store (e.g. metal snips, ball pein hammer (e.g. 12 oz size), propane torch and propane bottle, tongs or pliers, 2 plastic buckets, leather work gloves, hearing protection, fire extinguisher, other safety gear as necessary, rags, stiff plastic brush, compass with a pencil, flat bastard file (medium coarse), a lightly abrasive cleaner like baking soda, etc.);
Stump: you might find something else (wooden) to hammer on, and you can make a smooth depression in it, as I did, using power tools like a circular saw and side grinder;
"Pickling solution": (e.g. "Lime Away" or some other inexpensive alternative to "CLR" that is advertised for removing scale build-up in kettles and coffee makers): an industrial cleaning supplies store, or your favourite local hardware or building supply store. This type of cleaner will be a satisfactory (and cheaper) alternative to authentic jeweler's pickling solution.
Step 2: Organize Your Work Space
Find a place where you can hammer on the sheet metal without excessively annoying your household.
Find a (low) seat that will allow you to work (hammer) on the stump without wrecking your back or knees.
Have a place where you can heat the copper bowl with the propane torch without damaging the floor, or starting anything on fire.
Place the bucket of pickling solution and the bucket of fresh water close to where the bowl will be torched.
Step 3: Design Your Bowl
Use the compass to draw a (e.g. 6") circle on the copper sheet.
Cut out the circle with the metal snips. Try to complete the cut all at one time, using short strokes to avoid using the tip of the snips (which will leave blemishes). I wear gloves for this step as the edges of the disk (and scrap) can be extremely sharp; (you have been warned). You should now have a flat copper disk. (You can file the edge of the disk to remove irregularities and the tooth marks of the snips.)
Remove the plastic film, if present.
Draw two more concentric circles with the compass (e.g. 5" and 4" diameter). These will make it easier to keep the bowl a nice, symmetrically round shape. These will disappear as you work, but by then they will have served their purpose.
Step 4: Start Shaping the Bowl
Hammer along the perimeter of the disk, using the edge of the depression in the stump as a form to give the copper a curved shape, as the disk slowly becomes a bowl.
The intent is to use a lot of small taps - all in a line (as a long spiral starting at the outer edge of the disk).
As you work the copper, and it starts to get "work hardened", it will sound increasingly "tinny" (i.e. making a higher pitch as you hammer it).
As the copper gets work hardened, it becomes more difficult to shape it, and eventually it is susceptible to cracking.
After hammering about 3 time around the perimeter, it will be time to anneal the copper. (Yes, that's pretty soon...)
Step 5: Anneal the Copper
Light the propane torch and play the flame over the bowl, (inside or outside - it doesn't matter since copper is such a good conductor of heat).
You will want to wear leather work gloves and hold the bowl with tongs or pliers, (watch where you point the flame - don't start a fire in your back yard!)
As the copper heats, you will see the copper turn from bright to a dark red to electric blue to a dull blue grey, particularly when your move the flame away.
To anneal properly, the copper needs to get to the final blue-grey stage - be careful it is now very hot!
Drop the hot copper into the bucket of pickling solution, (try not to splash - it will make a loud "squelch" noise, which is fun).
You can agitate the copper, and after a couple of (or a few) minutes it will look clean(er) and you can transfer the copper to the bucket of clean water to rinse / brush / wipe off the copper oxide and pickling acid (which would make a mess of your clothes and tools).
The copper is now softened, cleaned and ready for more working (hammering).
Step 6: Rework and Anneal Again
Return to the "Shaping The Bowl" step, and repeat until you have a shape you are happy with - be patient, and persistent as this effort will eventually pay off with a result you can be proud of.
Step 7: Finish the Project
When you have a bowl shaped the way you like it, you might want to preserve that nice copper colour.
Do not anneal the bowl once you have the final shape.
Instead, put the bowl directly into the pickling solution and leave it there a good while, (say a half hour to 4 hours, depending on the strength of the solution and how bright you want the finish - don't worry, it won't dissolve away).
Next rinse the bowl in fresh water and scrub it well with a plastic brush (and a lightly abrasive cleaner like baking soda) until it really shines.
Dry it well, being sure to not leave oily fingerprints on the surface.
A clear plastic spray finish will keep the copper from oxidizing and preserve the characteristic copper colour; (I usually use a glossy finish, but sometimes a matte finish is nice).
Follow the spray manufacturer's directions and use several light coats, with the bowl suspended by a bent coat hanger or other stiff wire in a wind and dust-free space. (I use a respirator to ensure I don't breathe in the spray.)
Voilà - there you have it - ready to collect your errant coins or to keep you calm and collected during the next interminable teleconference!