Cyprus Copper: Celtic Cross by Martha Biggar

Inspiration Cross by Carson Sams.

Part 1: Experiments with Cyprus Copper

Here’s the back story to this unusual Celtic cross:  while Ed and I were working glass at the State Fair of Virginia, we met a nice young blacksmith named Carson Sams.  Carson did regular demonstrations during the ten days of the Fair, as did we, and we got to know each other pretty well.   I watched his demonstration of this cross and was floored by his techniques.  He started with three straight lengths of steel; the first piece he heated and beat and heated and beat until it became a ring.  The next piece he beat into a U-shape, and then he assembled the three pieces, as I’ve shown here, and beat the U-shape down to lock them in place.  This he called a friction fit.  He finally added through rivets to keep the shape in place.  He used his riveting hammer to add the texture at the end of each bar, flaring the ends as he hammered.

I was so fascinated by this process that I went back to our tent and made a small one out of silver metal clay.  I’ve done a few more small scale pendant pieces out of silver, but wanted to do something in a larger scale and so decided to give the new Cyprus Copper a try.  The only real modification I made to Carson’s basic technique was to start with a donut shape for the rounded part instead of a straight length.  I used a bit of slip to connect the pieces before firing, and used faux rivets to continue the design.  This takes a little patience and practice to get to work out, but is worth it in the end.

Now for our take on Cyprus Copper clay, developed by Cindy Silas and distributed by Cool Tools.  On opening the package, we noticed that the clay is triple-sealed and is fresh and soft to the touch, conditioning well.  The working period seems long, and, after resting in the packaging or our homemade humidor, pieces that are balled up to reuse come out pretty soft.  A big plus is that Cyprus Copper retains its shape when cut and doesn’t stretch, unlike some other copper clays.  Another benefit of working with Cyprus Copper is that it fires at a much lower temperature than other coppers on the market.

Test Strip.
Test strip earrings.

We encourage you to always make test strips when you fire base metal clays, even after you determine the best temperature for your kiln.  We make our test strips as pairs of simple dangle earrings, and place them near the center of the box of carbon.  After firing and cooling, remove these with tweezers, and if more time is needed the rest of the box is not disturbed and can be refired.  We generally use the late Bill Struve’s water test to check for sintering:  mix a drop of dish soap with ½ cup water, and then place a drop on the surface of your metal.  If it is completely sintered the drop will not be absorbed; the dish soap acts as a surfactant and lets the water wet the metal.  If the water sinks into the strip, you know it is not sintered and needs to be tucked back into the carbon and refired a bit hotter.   Pimples or pits are a sure sign that you fired too hot, hopefully not the entire box though!  Keep detailed records of your firings; you will notice changes in your kiln over time and you can compensate as you watch those changes.

Like most base metal clays, Cyprus benefits from a first, open firing (recommended on a wire rack but we used a kiln shelf with no problems) at 650F for 30 minutes.  Second firing, buried in coconut carbon, is 1600F for 3 hours.  Although Cyprus recommends a full ramp, we used a more conservative ramp of 800F per hour with great success.  We also recommend the coconut carbon for all our base metal firings.

Part 2: Step by step: Celtic Cross Pendant

You will need basic metal clay tools:  roller, slats or playing cards, scalpel, pin tool, circle template, cards for templates.  We often use some sort of neutral texture on the back of our pieces, in this case a strip of wallpaper in a woven texture. (Click on images to enlarge.)



Step 1:
Trace the provided pattern to make a larger cross. Or, reduce on a copier to make a smaller version.  Notice that we often cut patterns out of playing cards, they are stiff enough to use as a template, and cheap enough to cut several if needed.  I often transfer these templates to plastic after I work out all the kinks of a design.






Step 2:
Condition your clay: roll several balls of clay and store in the original packaging or a homemade humidor.  There are several versions on the market but you can make a simple one like ours with good plastic wrap and a sealable container.  Note that the sponge is below the plastic wrap and the clay is above it, never touching, or you have instant “mud”.  I always condition all the clay in a package; once the packaging is opened it never seals back up quite as well.  The sponge can be checked weekly and rewetted as needed.  Personally I keep my base metal clays in the refrigerator since my feeling is that it forms better when cool.





Step 3:
Assuming you are making the larger version, roll out the clay to 1.5mm, which are the purple slats from a slat set. This is about 6 cards thick; noting that cards vary from manufacturer to manufacturer and also change thickness from use.  You can use a thinner roll if you are making a smaller version, but I’ve not used anything thinner than 1mm (blue slats).











Step 4:
Cut the donut shape first and let it dry a bit before cutting the two strips. This will make the assembly easier.  I have let it dry completely (as in the next day) and that is acceptable but it’s harder to get the donut to soften up when the strips are put together if it’s that dry.  Note that we seldom force dry our work.






Step 5:
Cut the two strips next; I’ve adjusted the shape at the end of each strip to resemble Carson’s shaping with the hammer. Generally when we roll clay we roll a bit and turn 90° and continue rolling to make a rounded shape from which to cut.  But when cutting longer skinny pieces, rolling in one direction is best.   Cut the longer strip first, and let it sit for 15 or 20 minutes before cutting the shorter strip.  Once you cut the shorter strip, fold it immediately into a U-shape and be ready to start assembling.  Do not worry about rough places at this point.






Step 6:Looking at the pictures for reference, place the smaller strip inside the hole of the donut piece and thread the longer strip through. Note that the length of the top of the longer piece should be similar to the lengths of the shorter, horizontal, piece.






Step 7: Bend down the shorter horizontal arms to lock all the pieces in place. This is known as a friction fit.  If Cyprus Copper was not so flexible, I doubt seriously we would be able to complete this part of the project without a lot of cracks.






Step 8: I cut a simple template shape for the bail out of a playing card. Roll out 3 cards thick and cut based on the template.  Wet the surface and bend around a playing straw.  Tap the ends together, wait a few minutes, and slip onto the cross piece.  Check to make sure you don’t see any of the bail from the front.











Step 9:
Next day, after the piece is dried, I began cleaning up the edges. You can see several different versions here, one is whittled with a scalpel, one is smoothed with sponge pads but uses a carving tool to create a texture on the ends of the cross members.  Your piece can be as rough or as refined as you like.  Sometimes I whittle the donut piece before it is assembled so that the design is continuous.










Step 10: Firing time: I used the firing temperatures that are furnished with Cyprus Clay.  The only things I did were to lengthen the rate of ramp to 800F per hour instead of full ramp, and extend the time of the second firing to three hours.  You may call me cautious with these schedules, but I often fire pieces for students that are a wide variety of shapes, sizes, and thicknesses.  So my theory is to fire for the largest/thickest pieces in the box and everyone’s will be successful.






Step 11: After firing, let the box cool to below 300F. Why?  The carbon serves to bind oxygen and keep your piece from oxidizing.  If you take them out too hot, oxidation will occur and all your trouble with the carbon will be for naught.  Pieces may then be brushed to remove excess carbon, and finished as desired.  Most of these pieces were tumbled to add a high shine; the one on the left has a simple brushed finish.  I do not personally use any type of sealant on bronze or copper pieces; that is your choice.  I do tell customers that the metal color will soften with age and give instructions on keeping a shine if desired.

Step 12: To close, let me say that I’m really enjoying working with Cyprus Copper for several reasons:  nice color, ease of firing, lower temperature required, and flexibility!  I look forward to testing every new clay that comes along; I know there’s some I’ve missed, but I will say that I will be using a lot of Cyprus Copper going forward. We hope you will try this clay, experiment a bit on your own, but most of all have fun putting your own personal twist on this and other projects.

Martha Biggar: Martha and her husband Ed share a studio in Draper, Virgina.  They also offer small and private classes available