Platinum Guru

Soldering Gold and Platinum Together

When soldering gold and platinum together make certain to anneal both parts thoroughly before soldering.  These metals expand at different rates when heated.  If not thoroughly annealed stress tears may develop as the metal cools.  In addition, allow the metal to cool slowly after soldering.  Do Not quench the hot metals, rapid cooling increases the stress in the metals.

~ Brad

Platinum Jewelry,Fabrication,Casting

Torch Casting

For torch casting, a vertical centrifugal casting machine is the safest, most efficient, and most reliable way to cast platinum.  Vertical machines have high torque, produce a rapid centrifugal force, and require very little maintenance.  They are also safer than horizontal centrifuges - which, if a spill occurs, can fling molten metal in a waist-high circle around the shop.  A vertical machine has a straight centrifuge; major spills are very rare, and if one does occur, the flying metal is confined to a narrow vertical area.

The vertical casting machine should be mounted on a sturdy base so that one person can load the flask from the back while another person melts the metal at the front.  This two-person approach is important, since with the eye protection required to melt platinum, the operator sees virtually nothing but the glow of melting metal.  A machine that’s freestanding and bolted to the floor offers the best access.

Finally, be sure the crucible used for melting the metal is specifically designed for the higher temperatures required by platinum.  Use crucibles made from fused crystalline quartz or silica Si02+2.  Avoid graphite crucibles, since the carbon can contaminate the platinum.

~ Jurgen

Platinum Jewelry,Fabrication,Casting

Buffing with Abrasive Compound

When buffing with an abrasive compound, you'll need to generate enough heat to get the metal almost flowing.  To accomplish this, you'll want to select a larger diameter buff.  For example, a four inch buff will have a surface speed of about 3,600 feet per minute, while the speed of a six inch buff is about 5,400 feet per minute.  The greater the speed, the greater the heat.  You must also pay attention to the buffs physical characteristics: hard felt flat laps work best for corners and edges, while horse­hair brushes produce a nice shine on filigree and other details.

~ Jurgen

Platinum Jewelry,Fabrication,Casting

Gold Contamination In Platinum

Sometimes when annealing platinum it is possible to contaminate the platinum with other metals.  Some filings, or solder chips on a soldering surface, or any other metal on the bench can be melted into platinum thus contaminating the area.  With a ball burr, grind out the contamination; similar to the way a dentist cleans a cavity.  Now take a small piece of the same platinum alloy the object is made of and weld it to fill the hole.  Filing the excess metal away, you create an invisible repair.

To prevent this contamination from happening in the first place, soak your platinum in a 10% solution of Nitric acid for about 10 minutes, before annealing, welding or soldering.

~ Jurgen

Platinum Jewelry,Fabrication,Casting

Polishing using Tripoli

To polish platinum jewelry, first polish using platinum tripoli or white cutting compound on a muslin or hard felt wheel.  Polish in a diagonal direction, then turn the jewelry and polish in an opposite diagonal direction.  This cross polishing will result in an even, smooth finish.

Clean thoroughly in the ultrasonic, rinse, and dry.  Then polish with carrot or green rouge on a loose muslin buff.  Use the same cross polishing technique outlined above.  The results will be a consistent finish with increased efficiency and quality.

  ~ Brad

Platinum Jewelry,Fabrication,Casting

Jewelry Making: Fabricating a Princess and Baguette Pt Ring part 2

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Platinum Ring Fabrication,Jewelry Making,Custom Designed Jewelry

Polish Platinum using a Burnisher

To polish platinum successfully, it is important that all scratches are removed at the work bench.  This can be done with different and assorted abrasives using increasingly finer grits.

Once the scratches are removed, it is important to burnish the surface of the platinum.  This is done with a polished tungsten burnisher by hand, or with tum­bling devices.  If it is done by hand, the tool of choice is a tungsten burnisher, which rubs a highly polished rod of tungsten over the surface of the platinum.  Before you start, though, be sure the burnisher's surface is highly polished; if it's at all scratched, you will transfer those scratches to the ring.  Using a light oil for burnishing, such as oil of wintergreen, will prevent the burnisher from skipping and marring the platinum.

~ Jurgen

Platinum Jewelry,Fabrication,Casting

Casting Platinum

Did you know that it takes 10 tons of ore to produce one ounce of platinum?

Selecting the proper fuel to cast platinum is of utmost importance.  Do not use acetylene, since it has a high carbon content and expels carbon in the flame.  The platinum will absorb the carbon, leading to contamination and brittle castings.

Although propane, or LPG, is also a carbon-based fuel, it does not have the high carbon content that acetylene does, and therefore can be used for platinum casting.  Be aware, though, that even when mixed with oxygen, propane does not burn as hot as hydrogen and thus requires more time to melt the platinum.  This longer melting time can lead to porosity caused by gas absorption or debris - a direct result of keeping the metal in the melting crucible too long.  If you do use propane, pay particular attention to the flame: It should be no larger than 6 inches with a high oxygen setting.  A sample regulator setting would be 5 lbs. of propane with 40 lbs. of oxygen.

The most efficient way to melt platinum is with hydrogen combined with oxygen.  This fuel is carbon-free, and the high heat created by a proper hydrogen/oxygen mix melts platinum in seconds.  But even with hydrogen, a proper flame is crucial: If it’s too big, the flame will heat the surrounding crucible, adding to the melt time-and creating the same problems as those with propane.  Use as much oxygen as necessary to make a relatively small but oxidizing flame.  A sample regulator setting here would be 50 lbs. of hydrogen and 50 lbs. of oxygen.

~ Jurgen

Platinum Jewelry,Fabrication,Casting

Jewelry Making: Fabricating a Princess and Baguette Pt Ring part 1

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Platinum Ring Fabrication,Jewelry Making,Custom Designed Jewelry

Polishing Solder Joints

Always polish across solder joints.  Polishing with the solder joint will cause solder drag out.  To achieve cross polishing and polish across solder joints, first polish at a 60° angle to the joint.  Then turn the jewelry and polish in the opposite 60° angle.  This will achieve cross polishing while still polishing across the solder joint.

~ Brad

Platinum Jewelry,Fabrication,Casting