TruPd™ is the inexpensive option to Platinum and the superior product to White Gold that jewelers have been waiting for. It is suitable for all general fabrication techniques, and can withstand high levels of deformation between anneals. TruPd™ is Pure, White, Precious and Strong.
Palladium is a noble metal like Platinum that is used to create fine jewelry, and like its sister metal, Platinum, it can be used as an alloy of 95% purity. Compare this to White Gold alloys which require a large percentage of alloying metals. 18K Gold is only 75% pure and 14K Gold is only 58.5% pure.
Palladium is a white metal that, like Platinum, enhances the beauty of diamonds and gemstones set within it. Because its white color is natural and not the result of plating or alloying, Palladiumʼs white has great depth and luster.
Palladium is a Platinum Group Metal and is thirty times more rare than Gold.
Mined together with Platinum in less than a half-dozen regions around the globe, Palladium is truly a precious metal and a fitting symbol of love, life, and other rare gifts. Palladium provides the luxury, purity and look of Platinum for approximately the price of White Gold.
Palladium, like Platinum, is naturally strong and durable when used in a higher purity alloy than other metals such as Silver and Gold. Resulting in a more hypo allergenic product, Palladium does not suffer from prong failure, which is typical of many White Gold settings.
Palladium strikes a harmonious balance: more durable and less susceptible to tarnish than White Gold, but as malleable as Platinum.
Palladium can support delicate designs which are difficult to execute in White Gold yet has the malleability to facilitate easy sizing, repair, etc.
With a weight similar to fine Silver, Palladium has enough heft to convey luxury but it is notably lighter than Platinum, allowing for bigger and bolder design looks that remain wearable and affordable.
When World War II began, the British government declared Platinum a strategic metal and its use in non-military applications, including jewelry, was disallowed. As a result, Palladium made its first appearance in jewelry in 1939. The demand for wedding bands increased during the early 1940ʼs and many were made of Palladium.
In response to the Clean Air Act of 1970 and the rise of environmental or ʻgreenʼ legislation worldwide, both Palladium and Platinum were increasingly sought by the auto industry to produce the auto catalysts used to reduce car emissions. As Platinum became the more popular industrial metal, the demand and therefore the price of Palladium decreased and stabilized, bringing it increasingly into vogue for fine jewelry applications.
The Case for Palladium
The explosive growth in popularity of white metals over the last decade (particularly White Gold and Silver) creates a unique opportunity for Palladium jewelry. Palladium offers a more radiant white than White Gold, as well as many of the desired characteristics of Platinum without Platinumʼs price point (Platinum has seen a precipitous decrease in sales in the US market as it approaches $1,000 per oz.) This trend is strongest among the next generation of fine jewelry consumers: 73% of 18-24 year old adults prefer white metal for jewelry, compared to 40% in the 25+ group.
Because both Palladium and Platinum have similar characteristics, they are interchangeable in many applications and are usually derived from the same mines. While individual mines may differ, the current annual production is approximately 7 million ounces for each metal, approximately thirty times less than Gold.
Currently, Palladium is stabilized at about $200 per oz., while Platinum is more than $875/oz. This price differential, in addition to Palladiumʼs inherent beauty, strength, and durability, make it an irresistible candidate for fine jewelry making. TruPd™ is not the traditional 950 Palladium/Ruthenium alloy of the past. This new generation alloy is castable, malleable, durable, and is available at a value that offers benefits to both the jewelry retailer and the consumer.
A New White Metal
MJSA has recently introduced a white gold index defining whiteness as a function of the ASTM yellowness index.
TruPd™ has a yellowness index value of 11, making it far superior to the minimum requirements for a premium white alloy. TruPd™ will not require rhodium plating.
Grade 1 (good white) alloys have a yellowness index value of less than 19.
These alloys do not require rhodium plating.
950 Platinum-Ruthenium has a yellowness index value of 11.
Grade 2 (reasonable white) alloys have a yellowness index of between 19 and 24.5. Rhodium plating is described as “optional.”
Grade 3 (poor white) alloys have a yellowness index value of between 24.5 and 32. These require rhodium plating.
Improved Wear Resistance.
After simulated wear tests, TruPd™ has a 15% greater wear resistance over 14k white gold and 585 Platinum. For a comparison, under identical test conditions 950 Platinum/ Ruthenium has a 23% greater wear resistance over 14k White Gold and 585 Platinum.
Manufacturing jewelry with TruPd™ is easy. The properties of this metal are very similar to 10% iridium-platinum, so TruPd™ will hold no surprises for jewelers. Below are some tech-tips for using this revolutionary new metal.
Hereʼs the relevant data for investment casting.
• Density: 11.84 g/cm3 (6.24 troy ozs/in3)
• Melting range: 2462 – 2516°F (1350 – 1380°C).
• Casting temperature range: 2820 – 2910°F (1550 – 1600°C).
• Flask temperature range: 1250 – 1350°F (675 – 730°C).
• Investment type: Platinum (phosphate bonded).
• Crucible type: Carbon-free.
• Cover gas: Argon.
The first thing to note is that TruPd™ is a 95% pure platinum group metal and has a high melt range when compared to gold alloys, so you cannot treat it like a gold alloy. You must treat it like a platinum alloy. Always melt this alloy using carbon-free crucibles. These may be more expensive than carbon crucibles, but because the melt temperature is much lower than platinum, consumable life is significantly increased; crucibles will last for many more melts when compared to platinum casting. The high melting temperatures also require the use of phosphate investments.
Sprueing and gating must be similar to those used for platinum while you learn to use this alloy, however casters that are experienced with this alloy have stated they are now sprueing like gold for standard product such as rings and settings. For best results, cast trees with objects of similar size and mass until you feel confident with TruPd™.
Covering the melt with an argon atmosphere during casting is also very important. Palladium dissolves excessive amounts of oxygen and hydrogen which it releases on solidification, causing gas porosity. This is a major problem with 5% ruthenium-palladium alloys, when “Swiss cheese” was the usual result! TruPd™ has none of these problems. The composition has been designed to “fool” the alloy into thinking itʼs not palladium as far as gas absorption is concerned. But, do not overheat the alloy when casting or you will run into trouble with porosity.
Gas absorption also dictates casting machinery choice. We recommend you cast TruPd™ using machinery that uses induction heating and has a sealed melt chamber. These machines will allow for the use of an argon cover gas to be used. TruPd™ has been successfully cast using induction heating and an open chamber, and a gas torch set up, but this is more difficult than sealed chamber induction for the above reasons. If you need to torch cast, make sure you use propane and not hydrogen as your gas supply. But for trouble-free casting, use either induction method.
TruPd is very kind to centrifugal casting since it does not have the density and therefore energy of platinum when cast this way. Whereas care needs to be taken when centrifugally casting platinum alloys so that the mass of platinum does not “slam” into the investment, causing defects, TruPd™ has none of these problems. Larger volume charges and trees can be cast for this reason.
All sizes, shapes and types of castings are possible, from detailed to heavy section. If you do not have the equipment to cast TruPd™, Hoover & Strong offers a contract casting service.
Fabricating from Mill Products
TruPd™ can be fabricated like any other jewelry alloy. It is malleable and so can be easily fabricated and shaped, and can withstand high levels of deformation between anneals. It is an excellent choice for delicate work, and can be easily engraved. Below are some properties of TruPd™:
Hardness: As-cast – 115 HV
Hard rolled: 180HV
Elongation: 40% +
Density: 11.84 g/cm3 (6.24 troy ozs/in3)
You can roll TruPd™ to thin gauges using inexpensive studio-type rolls with no difficulty, and annealing is very easily achieved using either a furnace or a torch:
Furnace anneal: 1290° – 1650°F (700 – 900°C)
Torch anneal: Heat to orange yellow color 30 – 60 seconds.
When annealing TruPd™ quenching is not necessary, but it is not detrimental either. There are none of the problems encountered with annealing nickel white gold alloys. It does not fire crack, quench crack or stress corrosion crack.
This is what can happen when you anneal a nickel white gold, which all jewelers will recognize. The item goes into the furnace in one piece, and comes out in….more than one piece.
When soldering TruPd™ you donʼt need to use a flux because the soldering temperatures are too high. Use techniques and safety equipment typically used when soldering platinum. A little more caution may be needed because, once again, gas absorption can take place. This will only be a problem if youʼre doing very large fillets or using plumb solders which have high palladium contents. We advise using our hard, medium and easy palladium solders, specifically designed for best results when joining TruPd™.
Always use hard palladium solder wherever possible, because this will be the best color match and give the most ductile joint. Having said this, all Hoover & Strong step solders work great.
Remember, if soldering TruPd™ to karat gold, always use a karat gold solder. The palladium solders melt too high for karat gold alloys – youʼll melt the karat gold before the palladium solder! And remember to use a flux. Youʼll need it at these temperatures to keep the karat gold clean.
It is unusual, but if TruPd™ exhibits a slight discoloration during high temperature soldering, this is very easily removed with either light abrasion or by torching with a neutral or mildly reducing flame. TruPd™ does not exhibit surface discoloration when soldered using karat gold solders.
Because of the tendency to absorb gas when liquid, torch welding palladium alloys is not recommended. Once again, this technique has been done successfully, but it is a difficult process to get a join that is porosity free.
Laser welding is great for casting repair work. Use an argon atmosphere in the chamber, keep the filler wire to a minimum diameter – say 0.010” – and do small fillets often and there is no problem. This again keeps the liquid metal pool to a minimum.
TruPd™ can also be joined by welding with a laser, but again this can be more of a challenge if larger areas are to be joined and until you gain some experience with it. It may sound like TruPd™ is hard to solder and laser weld but it isnʼt. If you can join platinum alloys, you can join TruPd™. You just need to be aware of the potential problems, as you do with all metals. If you have any doubts, read the following quote from one of our customers, Steve Satow:
“I use TruPd™ all the time to replace white gold on prong tips and bezels. It balls up like plat and because it melts at a higher temp than gold you can use the dissimilar melting temps to your advantage. I love to use 30 gauge wire to re-tip small melee from .005ct to .07ct. I set the laser just hot enough to ball the wire up, then place it over the worn prong and fuse it into the white gold using a conductive laser welding technique I first discovered with Platinum and can now use with Palladium. The perfectly formed ball fuses into the white gold and maintains its form with out melting flat like a white gold alloy would”
To see an example of Steveʼs work, go to our website at www.hooverandstrong.com.
When working with TruPd™, it is preferable to have a separate workspace and separate tools, as you would when working with platinum alloys. However, TruPd™ is less sensitive to impurities and contamination than platinum alloys, so although preferable and best practice, this is not a “must do”. TruPd™ can take more “abuse” than platinum. If you canʼt set aside space and tools just for TruPd™, make sure your tools and work area are clean and contaminant-free before starting to work on your jewelry.
Castings and fabricated jewelry can be cleaned up using standard equipment, techniques and compounds that you would employ for platinum. You can use your current brand of abrasives, compounds and wheels. When working with TruPd™ there is a distinct advantage over platinum alloys; fewer pre-finishing steps are required. In this sense working with TruPd™ is more like working with gold alloys. For final polishing, use intermediate and fine platinum rouges for best results. These are our finishing recommendations. As with any new metal, experiment with different techniques and compounds, and find what works for you!
Can broken prongs and lost stones be avoided? If you use nickel white gold settings you are using an alloy that is known to fire crack, quench crack and stress corrosion crack. These problems are exacerbated by notching to fit in your stone…this notch is a “stress raiser” and can lead to failure in sensitive and brittle metals. When you bend tips over you stress this even more. So why use a metal that is set up, or potentially set up, to fail? Especially when this metal is more expensive than the alternative. Then as the final insult, you have to rhodium plate it, with the potential that at some stage, your customer will be back complaining that their white gold ring is turning yellow!
Use TruPd™ and you can do all of this without fear. No cracks or failures, easy to set, no need to rhodium plate, and inexpensive. And itʼs available in tru-seat for settings. What are you waiting for? TruPd™ is an excellent choice for setting. You can set any type with ease…tiffany settings, bezels, pave, no problems. The malleability makes it easy, but you get work hardening as well, just like platinum alloys, so stones are secure. There is little or no spring back in TruPd™, so more delicate stones can be set with comparative confidence, especially compared to setting with nickel white gold.
These alloys are great to use when you need to set lots of small stones. Again think about doing this with a hard and often brittle nickel white gold alloy.
When you start working with TruPd™ you can maximize your refining return with a few simple steps. First, keep TruPd™ hard scrap separate from other precious hard scrap. It will maximize your return and speed the settlement. Also, if at all possible keep palladium filings separate.
Hoover & Strong will always outright purchase pieces marked 950Pd.
For further reference, see the excellent series of articles on working with TruPd™ by Mark B. Mann, Visual Communications Inc. These were first published in Professional Jeweler Magazine, and can be found on our website at www.hooverandstrong.com.
Technical inquiries regarding TruPd™? Call us and ask for Stewart Grice or Mike Young.
Copyright 2006 Stewart Grice.
Photographs by Mark B. Mann, Visual Communications Inc.