BAGS AND BOXES by Anita Dakowski
Workshop by Linda Connelly
Guild Conference 14th April 2012.
MATERIALS: Copper shim and copper wire. Wet process enamels: flux and white. Enamels of own choice. Klyrfire, Pennybrite/Ajax cleaner. Flock and applicator (optional).
TOOLS:. Embossing tools (steel), ruler (steel), cutting mat, old thick soft material (blanket) to emboss on, old leather gloves (protect against sharp edges). Scissors: large and small. Marker for metal. Wooden pottery knife tool. Tweezers, sieves, paint brushes and and toothbrush. Water spray bottle. Paper towels for drying. Line patterns for inspiration or copying. Glass seed beads. Knitting or crochet hooks. Hole punch or darning needle in a cork. Tracing wheels for patterns.
DEMONSTRATION: Linda showed us examples of boxes and handbags she had made, providing an information sheet with two sheets of pre-printed patterns showing tried and tested box models.
For Boxes, Linda showed us how to make up our own designs, suggesting that if we do, best first make them up in card to make sure all pieces fit; advising that the lid should be 5% larger than the pattern, due to the expansion of copper and the addition of enamel to the surface.
For Handbags, front and back should be cut; with 3 gussets longer than the sides. Cut to size on the item. N.B. The mouth of the kiln must be large enough to take the Bag side-on with a little space to spare for maneuvering (this improves its strength in the kiln).
Linda then demonstrated marking out the copper through the paper pattern. By pressing hard with embossing tools you define the ends of the lines with dots. Then, accurately join up the dots with a marker so that all the parts to be cut out, as well as the folds, are clear. Cut the shim with the large scissors. Placing the copper on the piece of old blanket or thick soft material draw your design in the copper using the embossing tools. It can be worth experimenting with a small piece of shim and the different sized tools, to get the right sharpness of line for your design. Turn the shim over and emboss the other side, following the lines you have previously made, to get distinct marks. The embossing strengthens the shim.
Linda also showed us how to use a paper crimper to get a different effect. Using this method the copper becomes hard to work after passing the shim once through the crimper and needs annealing (heating the copper to a point in the kiln where it becomes soft once again). You can pass the shim through the paper crimper a second time at right angles to get a square pattern.
Once the embossing is complete turn in the corners and make folds in the shim. To create the sides of the top of the box, fold through 90. Make sure the corners are even and as tightly pressed together as possible. The sides and corners should be crisp and straight. Use the tweezers on the corners. Repeat for the bottom of the box. On pyramid form boxes it is necessary to sew a few stitches in copper wire into the sides, to hold them together. In this case it is easier to begin from the inside which means there are fewer stitches made from those difficult to get to areas!
They need sewing together. Put wrong sides together and overstitch. With the sides of the bag and the gusset together make holes with hole punch or needle-in-cork. First attach the bottom gusset by threading the copper wire through each hole, as if you were sewing but being careful not to pull the end through; just bend the wire at the ends rather than trying to knot it. Do not pull too hard; just secure the sides, as the enamel will hold the wire in place.
Choose firing stilt first as you won’t easily be able to handle the piece once the enamel is applied.
Clean the item using the toothbrush with cleaner, getting into corners and all crevasses, work from the inside out. Rinse well and dry with kitchen paper. Handle by edges to avoid getting finger marks on it.
Apply a thin coat of wet process enamel with a paint brush - either white or flux - making sure that the enamel is even on both sides. Water it down if necessary. Start from the inside,suggest white or coloured enamel for this; do not let the enamel puddle or you won’t get an even finish.Dry and enamel the outside. The aim is to cover both sides of metal to avoid getting firescale on bare metal. Before the flux was dry, we lightly sifted some transparent leaded jewellery flux through a small sieve which “held" the enamel better. We then dried the boxes on stilts or meshes, on top of the kiln. When dry they were fired at about 780- 800°C. for a few seconds. The second coat could be further wet process enamel or dry powder, applied after gumming the surface with mist from spray bottle containing water and a little gum. When this was dry the item was fired again.
When desired finish was arrived at, the final stage was to flock the inside. This was achieved by gumming the interior and using a flocking gun. Enclose all safely in a plastic bag and puff with flock via applicator.
We all decided to use Linda's pre-printed Box patterns due to the time constraints of the workshop. We found that it was most important to make sure the edges were as square and as sharp as possible.I found it was important not to emboss the bottom too heavily as it could result in the finished item not sitting evenly. On larger pieces this could be got around by making the bottom slightly concave so that the box sat on its edges. We used different enamels. Some used coloured wet process throughout; this gave a more solid look to the boxes. Some let them burn out which brought the oxides through and I covered mine with transparents which ended by giving a misty finish.
By Raymond Jackson
Some Observations on Applying Transparent Enamels to Copper
Silver and gold are attractive metals for enamelling because of their intrinsic value and because they possess high reflecting properties, allowing transparent enamels to be shown to best advantage. In addition, gold and silver alloys do not oxidize significantly at the temperatures needed to fuse the enamels to them. Although minor oxidation can cause some transparent enamels to discolour, there are well established techniques to enable enamel clarity and colour to be of a very high order.
In contrast, copper presents a problem for transparent enamels, namely the rapid and significant oxidation that takes place when copper is heated to enamelling temperatures, (in the range 7000C – 10000C). Inexperienced enamellers might conclude it virtually impossible to achieve results quite as good as those on gold or silver. This may be true, but there is much published information on how to mitigate the discoloration of transparent enamels caused by the copper oxide that develops on the surface of the metal.
Read the full article
By Dorothy Cockrell and Joseph A. Ontko Ph.D.
Silver nitrate and raku firing have long been used to produce silvery patterns on enamel. There are certain difficulties in this process, ranging from the procurement of silver nitrate, the necessity of keeping the crystals and solutions away from light lest they deteriorate, through problems connected with controlling the various solutions, to the deep brown staining which can develop on hands, clothing, and work surfaces. Mixing an appropriate strength of any solution often requires making several test pieces.
It occurred to me that perhaps more modern materials could be used to produce the same effects with less trouble.
Therefore when packing my tutorial tool box for a raku firing workshop at the John C. Campbell Folk School, I included a very ancient unused piece of the original type of silver PMC (Precious Metal Clay). It was so old that it had hardened into a small bullet and re-quired breaking up and two days soaking in water to re-constitute it.
In a quiet moment I painted some of the resulting slip onto a pre- enamelled copper blank and fired it to burn off the organic binder. The result was a greyish patch of enamel.
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By Raymond Jackson
Common Silver Alloys for Enamelling
Sterling silver (7.5% copper in a minimum of 92.5% silver) is widely used for silver articles including jewellery and for enamelling the same. The copper content increases the strength and hardness.
Britannia silver (a minimum silver content of 95.8% and the remainder largely copper) is less widely used but is especially suitable for taking stamps and dies. Being softer than Sterling silver, it is more susceptible to bowing unless counter enamelled. However, some experts state that enamel colours are truer when fired on this alloy. As to cost, there is virtually no difference.
It is reported that the presence of impurities even at low levels can affect the adhesion of enamels. In particular, Selenium and Teluriam can cause problems. To avoid this potential problem, reputable silver suppliers use only fine silver and pure copper in the initial alloy casting process.
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