The Alabama Mineral and Lapidary Society is a non-profit organization for people interested in geology, mineralogy, paleontology and lapidary arts. |
Edwin Elam was involved with the lapidary hobby from the early 1970s until his death in February 2010. Ed was AMLS' Nominee for Southeast Federation Rockhound of the Year for 2008. |
I used 25 pins for this piece. As a general guideline, pins will
need to be placed about 10mm to 12mm apart. I try to keep my pins
4mm to 5mm away from each joint, because if your flux runs over to a
pin, your solder may do so as well, soldering the pin to the channel
wire. If this happens, you must cut and file the pin off your
channel wire.
Measure the total length of the wires for your piece and cut off that length from the coil. Straighten your wire by placing it on a smooth surface and rubbing down the length of the wire with the handle of a ring mandrel, a block of wood, or something similar. Your wire must be completely straight. You will find that if the wires have little bends in them, you will have a hard time cutting your stones to fit. You are now ready to cut, file, shape and pin down your first wire. I usually choose the longest wire in the pattern. In this project, do the perimeter wire first. |
Use your chain-nose pliers to put the pins in the brick. They
should start perpendicular to the brick and go straight down. Push
the pin most of the way in, turn the hook to the right position, and
use the side of your pliers to finish pushing the pin down. Remember
that your objective is to pin your channel wire on the lines of the
pattern, to keep the wire perpendicular to the brick, and when your
piece is pinned down, to have the wires level across the top of your
piece.
Once the outside wire is in place, cut the remainder of your wires. Use your jeweler's saw with a 4/0 blade. File the ends square and pin in place. Check that the wires are perpendicular to the brick, your joints are tight, and the wires are level across the top before going to the next step. |
The purpose of the operation you have just completed is to get
rid of the paper pattern and to keep the ash from interfering with
your soldering of the joints in the channel wire. The boric
acid/alcohol solution also cleans your silver and helps prepare it
for soldering.
Before you begin soldering, let me cover some of the materials, equipment and methods I use. I use a Goss torch with a #2 and a #3 tip. The Prestolite torch is of the same design and has the same tip sizes. The #2 tip (medium flame) is used for the first part of the soldering and the #3 tip (large flame) is needed to solder the channel wires to the backing plate. I have always used a paste flux, specifically Handy Flux. If you are accustomed to using other kinds of fluxes, I would suggest you use them. In this project and in my classes, we never use anything except easy solder. This is the solder that one of my catalogs specifies as Braze 650, which is 65 percent silver, 20 percent copper, and 15 percent zinc, and has a melting point of 1,240 degrees. This may not coincide with what you were taught in beginning silversmithing, but everyone who teaches channel work uses this method. I cut my sheet solder into snippets roughly 2mm by 2mm. |
Take the frame of your piece off the brick and pickle it. Check
the soldered joints. If any areas in the wire have bent from the
heating, you can do some slight adjusting and straightening.
Check the framework against one of the patterns that you saved. Once you are satisfied with the framework, you have to file the back of the frame so that it sits flat on the sheet of silver you are using for a backing plate. I place the frame on my fingers, and using a fine-cut flat file, gently file in different directions until it is completely flat. You can also put a medium-grit sandpaper on a flat surface and gently lap the piece until it sits flat on your silver sheet without any gaps showing. Position your frame on the silver sheet and mark around the outside. I find a fine-tip, permanent-ink pen ideal for this. Saw out the backing plate using your jeweler's saw with a 4/0 or finer blade and some saw blade lubricant. If you want to stamp your backing plate with a "Sterling" stamp, do so now. To solder the channel wire frame to the backing plate, pickle both pieces to be sure they are clean. Lightly coat the whole surface of the backing plate with paste flux. Put the backing plate on your fire brick and align the channel wire on the backing plate. Dry the flux with your torch. Position five or six snippets of solder inside the pockets of the frame. They must be flat on the backing plate and also be touching a channel wire. Just space them around within the frame. You may want to warm the flux again to help stick the solder in place. Change your torch tip to the #3 tip. A reasonably large flame is required for this operation. Once again, it may help to rehearse the procedure before lighting the torch. |
I would suggest for your first channel work piece that you choose stones such as agate and jasper. Avoid any type of stone that you might have trouble polishing. Slabs for channel work need to be 3mm to 4mm thick. They are not generally available on the market. If you do not have a slab saw, perhaps you can cut enough slabs on your trim saw for your piece. The great thing about channel work is that it does not require a lot of stone, so three small slabs of the color you want to use will be sufficient. If you must work with slabs that have been cut 7mm to 9mm thick for cabbing, you must thin your stones down, either on the trim saw or by grinding on the coarse wheel of your cabbing machine. |
Your goal is to fit each stone so that it will go into the pocket without forcing and will drop back out. There should be no significant gap between the stone and the channel wire. This is not as difficult as you might imagine. If you have an adjustable cab rest, set it so that the edges of the stone are 90 degrees to the face of the stone. If you don't have a cab rest, determine the point on your wheel that will give you the right angle, and always try to grind at that point. The tendency is to taper the edge slightly when you're grinding for fit. If you taper your stone, when you grind down the face of the piece to finish the stones, you may end up with gaps between the stone and the channel wire. |
Use a fairly generous amount of a clear-drying epoxy in each
pocket and keep a paper towel, moist with alcohol, handy to remove
any epoxy that squeezes out.
When the epoxy has set, grind and polish the surface of your channel work. This is a fairly straightforward process if you are using a flat lap-type machine. Use the coarse lap to grind the surface down until you have touched all the channel wires and all the stones. This is easy to see, because the silver will appear brighter where the lap touches it. After that, follow the steps you would use to polish any flat piece. I finish my channel work on a conventional-type cabbing machine. I am presently using a Diamond Pacific Genie, which has 80, 220, 280, 600, 1200 and 14000 grit wheels. I have a large, slow-speed leather buffing machine, so I finish off with tin oxide on leather. Many people have expressed a fear that the silver is somehow going to contaminate their wheels or polishing buffs. I have done a lot of cabbing and channel work over the years using a variety of wheels and buffs, and have never seen any adverse effects. |