950 Palladium
Manufacturing Tips and Techniques
By Mark and Lainie Mann, Mann Design Group, Inc.
The “other white metal” is making its presence known and it won’t be long before light, bright and white 950 palladium
products find their way to your workbench, either as merchandise from your store or customers’ jewelry taken in for service or alteration. Notable designers and manufacturers like Frederick Goldman, Scott Kay, and Lieberfarb have incorporated 950 palladium products in their bridal lines for over a year.
A growing list of 950 palladium suppliers and manufacturers of sheet, wire and casting grain as well as findings and
mountings like Keystone Findings, Telford, PA, R-Findings, Rochester, NY and PMI, Dallas, TX are creating products for the
supply and service of palladium jewelry for retailers. This series of articles featuring the manufacturing of palladium jewelry is offered to enhance your working knowledge of palladium on the sales floor and at the jewelers’ bench.
This installment features information, tips and techniques for working with palladium through a manufacturing sequence required to produce this necklace and earrings.
These pieces were cast by TechForm, Portland, OR. Palladium has a lower
melting point and specific gravity
than platinum but still requires the use of platinum casting materials
and procedures. (An overview of
palladium casting techniques was published in the June 2006 issue of JCK.) Shown are the cast palladium links for the necklace.
There is a rough surface on the cast
links even though the wax model was
smooth. This is due to the nature of
the shell and investment mold used for the casting process. Even though
the necklace links were small and lightweight, multiple gates were used
requiring extra removal time during the pre-finishing operation. The links were filed with No. 4 files and sanded
with 220, 400 and 600 grit 3M micro-
finishing film sanding sticks.
Tip: Filing and sanding palladium requires an
extra step or two over pre-finishing techniques
used for karat gold but less steps than when
pre-finishing platinum.
Pre-finishing and pre-polishing steps can generate significant waste. To minimize flying debris and collect it more efficiently, a fish-mouth style dust collector was modified with Plexiglas and mounted vertically.
This adaptation shields the user
while maximizing visibility and waste
collection and allowing more bench space.
Tip: The fish-mouth is connected to a bench side dust collector, vacuum and filters which trap the precious metal waste for refining.
The bottom surfaces of the links were
sanded with a variable speed motor
and 3M diamond polishing cloth with grits ranging from 400 to 3,000.
A protective material was wrapped around the operator’s holding finger
to enhance safety.
Tip: 5 grits were used to pre-finish the bottoms. A lustrous finish remained after the last step using 3,000 grit. The small variable speed
motor was placed in a metals retention pan. When this process is completed, it’s easy to
collect the resulting debris for refining.
With the parting lines removed and
the rough texture reduced, 3M radial bristle discs are then used on a
variable speed motor to pre-polish the links. Seven color coded wheels
are used which range from 80 to
ultra-fine grit. No polishing compound
is required with these wheels and a nice polish is produced.
Assembly
The links had small connector pieces in place on the wax models but failed
to fill during the casting process. After casting and pre-finishing, replacement jump rings were
attached by tack welding using ABI’s Tack II.
Tip: Palladium flow characteristics are poor
and thin or inconsistent areas in a model are
vulnerable to no-fill.
To make more connector parts, wire measuring 0.6 millimeters is made from square wire stock. The 950 palladium square wire is annealed by placing it on a platinum soldering block and directly heating and bringing the temperature of it up to an orange glow. The torch is held on the wire only moments after it reaches the orange glow.
Tip: Use a platinum soldering block for
annealing and soldering parts. Also use eye protection. In this example, a No. 5 rated welding lenses is used to shield harmful white light. For soldering karat gold to palladium,
the item should be protected with firecoating solution. Standard gold soldering flux and easy flowing gold solders should also be used.
A lead is attached to the negative
terminal of the tack welding unit and a brass lined pliers lead is attached to
the positive terminal. The jump ring
is being held by the brass pliers lead. A single pulse of energy is released by depressing the foot pedal and the
jump ring is temporarily attached to
the center link.
Tip: Tack-welding aids in holding parts in place while soldering. Tungsten carbide or titanium tipped tweezers should be used to hold parts when they are not tacked prior to soldering.
After annealing and cooling, the size of the wire is reduced in the rolling mill. 950 palladium is malleable and can be cold worked far longer than karat gold. The square wire is rolled
flat.
Tip: Make sure your rolling mill is free of waste and debris from gold and platinum rolling
projects. Use clean rollers to avoid metal
transfer and contamination.
The connector jump rings are soldered using easy flowing palladium solder. No holding devices are
necessary during the soldering procedure because the parts are tacked.
Tip: When soldering palladium to palladium,
no firecoat solution or flux is required. Use
rated No. 5 or darker welding lenses for eye protection during high heat palladium soldering applications. Palladium will loose its polished luster during soldering but it is easily restored through minor re-polishing. Palladium solder
is available in hard, medium and easy flowing
temperatures or lower temperature platinum solder can be used.
The connectors are tacked and then soldered using easy palladium solder.
Tip: With the tacked parts, a mild but direct
soldering technique is used to join the pieces.
When cast, the spacer wire at each end of the wax models is there to keep the link aligned during the
casting process. It is removed and
holes are simultaneously drilled through each side of the link ends after casting. The wire is threaded through them and the pear shaped palladium connector. The gold link is
firecoated, fluxed and soldered.
Different than platinum, palladium loses its polished luster when soldered. Notice the small area of bluish surface discoloration in the middle portion of this link. The
polished luster is very quick to restore
using a torch with natural gas and
oxygen and a neutral flame and the
discoloration disappears.
Final Polishing and Finishing
Final polishing required 3 steps for both the karat gold and palladium. It began with 800 grit compound using a small polishing brush and wheels. For the second step, 4,000 grit compound, brushes and wheels were
used. For the final step, 8,000 grit
compound was used.
Tip: The first step of the final polishing process
is done without the gemstones in place.
Summary
The weight of the necklace is very light. The specific gravity of palladium is nearly half of the weight
of platinum so the larger links do not weigh the piece down when assembled. In fact the weight of the palladium links is comparable to the same made in white gold. The color distinction in two-tone
jewelry is an obvious advantage. The palladium is white with a bright polished surface alongside the high polished yellow gold links – a contrast difficult to discern between yellow and non-rhodium-plated
white gold. As a member of the platinum group of metals (PGM) palladium is white and therefore stays
white, so plating (and re-plating) with rhodium is never necessary.
Photographs by Mark B. Mann, Mann Design Group, Inc.
