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Platinum Bars

R0,00

Cape Precious Metals is one of only a few refineries in South Africa that handles the recovery of Platinum group metals from waste material. We manufacture to a purity of  99.99%.

Order Codes:

Platinum CU

Alloy Composition   95% PT (CU)
Colour   White
Melting Range   1740 – 1755°C
Solders   1020, 1200 & 1400
Specific Gravity   20
Annealing Colour   Cherry Red

 

Best used for

  • Bench Work
  • Casting
  • Rolling


Hints, Tips & Uses

  • General all purpose alloy
  • Medium to soft alloy

Platinum RU

Alloy Composition   95% PT (RU)
Colour   White
Melting Range   1780 – 1800°C
Solders   1020, 1200, 1400 & 1600
Specific Gravity   20.7
Annealing Colour   Cherry Red

 

Best used for

  • Bench Work
  • Casting
  • Rolling


Hints, Tips & Uses

  • General all purpose alloy
  • Universal alloy which can be cast, machined and used for bench

Platinum COBALT

Alloy Composition   95% PT (CO)
Colour   White
Melting Range   1740 – 1755°C
Solders   1400 & 1600
Specific Gravity   20.8
Annealing Colour   Cherry Red

 

Best used for

  • Casting


Hints, Tips & Uses

  • High hardness and fine grain
  • This alloy is magnetic and very hard
  • Preferred for casting
  • Used for fine wire & chain making

Platinum AU

Alloy Composition   95% PT (AU)
Colour   White
Melting Range   1740-1755°C
Solders   1020 & 1200
Specific Gravity   21.3
Annealing Colour   Cherry Red

 

Best used for

  • Bench Work
  • Casting
  • Rolling


Hints, Tips & Uses

  • General all purpose alloy
  • Medium to soft alloy

Polishing Platinum

  • When polishing platinum, it is important to remove all scratches before the polishing process
  • When filing, file gently with a diagonal movement. Then repeat with a diagonal movement perpendicular to the first one.
  • Remove file marks with abrasive paper such as 400, 600 and finer paper
  • Be sure to use the files and abrasive paper on platinum to avoid contamination
  • Reduce the surface to at least a 600 grid finish on the bench
  • Burnish the ring with a polished Tungsten burnisher
  • Use platinum polishing compound only for luster
  • Use 2000, 4000 and 8000 grid polishing compounds
  • When polishing platinum that is joined to gold, be sure the platinum is polished completely before polishing the gold
  • Check with tool suppliers for brand recommendations

 

Things to consider

  • File gently with a diagonal movement. Then repeat with a diagonal movement perpendicular to the first one, creating a criss-cross pattern
  • Because gold polishes faster than platinum, it is easy to over-polish the gold portion by trying to polish the platinum and thus ruin the piece.
  • Hard felt whells and stitched buffs work well on platinum
  • Burnishing is essential
  • The polishing process will highlight, rather than remove scratches. They must be removed at the bench

Burnishing Platinum

Why Burnish?

Burnishing will work-harden the surface, compress it, close small cavities and make polishing easier. When done properly it reduces rejects from the final polish and saves time.

 

Benefits of burnishing Platinum:

Burnishing adds extra hardness to the casting, preventing a score of problems such as bending, taking on the shape of the finger, and scratching more easily

 

 

Reference guide to burnishing:

All platinum casting should be burnished

 

How to burnish:

Using a highly polished tungsten burnisher, rub across the surface of the piece of jewelery. Note, burnishing can also be accomplished using a motor tool

 

Tips for better burnishing:

  • Use a small amount of oil to lubricate the burnisher. This prevents scratching and makes a smoother surface possible
  • Any scratch on the burnisher will be transferred to the piece. The more polished the burnisher, the better the surface of the piece will be burnished
  • Use considerable pressure and force. This action will move the surface, compress it and close small porosity holes. The rubbing action hardens the surface, making the final polish much easier.

Contamination

When contaminated platinum is being stressed through rolling, drawing or hammering, it will crack and become unusable

 

Possible causes of contamination during soldering or welding:

  • Using carbon soldering surface (charcoal)
  • Abrasive rolled into the Pt surface during fabrication
  • Filings from other precious or non-precious metals.
  • Using flux or Fire coat on Pt during high temperature operation
  • Using steel tweezers near the soldering flame
  • Oil, grease or soap used during drawing, rolling or general working

 

Tips to avoid contamination:

  • Use only oxidizing flames, avoid redusing flames during soldering or welding
  • Avoid trapping contaminants in the Pt during cold working
  • Dedicate files, sanding sticks and bench pins to platinum
  • Do not weld or solder with acetylene / oxygen flames
  • Use only Natural gas / Oxygen, Propane / Oxygen of Hydrogen / Oxygen
  • When using a water torch, disable the flux feature

 

Tips on what not to do:

  • Don’t use Acetylene Gas. Only Natural Gas, Hydrogen or Propane will work with Platinum
  • Don’t weld without eye protection. UV radiation WILL damage your eyes
  • Don’t weld when stones are nearby. The welding process will damage most stones
  • Don’t use your soldering pick or steel stweezers near the flame, as they may contaminate the platinum
  • Don’t weld on a charcoal block. Platinum and Carbon do not get along.

A guide to Platinum Alloys

Click on this link to download the A guide to Platinum Alloys PDF

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