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A Step-by-Step Guide to Working With Platinum

working with platinum blog header

Platinum in its finished state is an absolutely beautiful metal. It can also be a little tricky when working it due to the softness of the metal. Knowing what tools and techniques to use can make the job a whole lot easier.

 

Here are a few things you need to know about working with platinum.

First Thing’s First

The first step is knowing which platinum alloy you are working with. Platinum/cobalt,
platinum/ruthenium, or platinum/iridium. Each alloy has its advantages and disadvantages. Platinum can be a soft metal as far as finishing goes, platinum/iridium being the softest of the 3 mentioned above. Platinum/cobalt is the hardest of the three as cast.

If you’re not sure of the platinum alloy there are a couple of ways to check, one being the stamp. Platinum/cobalt and platinum/ruthenium may be stamped just PLAT, or Pt950, whereas platinum/iridium should be stamped Pt900. Of the cobalt and ruthenium a simple magnet can distinguish between the 2. Cobalt is slightly magnetic. Use a magnet to tell if a ring is made of a platinum/cobalt alloy.

Choose Your Tools Wisely

It’s important to have the right tools – burnishers, platinum sand paper in several grits, rubber wheels, and ceramic stones ext. A list of tools is at the end of the article. It is also a good idea to keep a separate set of tools just for platinum to prevent contamination, and make polishing the platinum easier. Another tip to a beautifully polished piece is to make sure to pre-clean the grit from the piece after prepping, leaving the dirt and grit on the piece can transfer to the buff making it difficult to get the high polish results without a scratchy looking haze on the piece.

Let’s Get Started

If you have a vibratory tumbler with stainless steel shot (pins, balls, and diagonal Stainless steel shot) tumble the piece for at least 20 minutes. This will shine up the areas that are hard to reach as well as work hardening the metal, making finishing the platinum a little easier to work with. If you don’t have a tumble, you can burnish the piece using a flex shaft and a tungsten-carbide burnisher or by hand using a hand burnisher. Burnishing the piece will save time when removing the scratches from the prepping process.

Round out the piece first to make sure you don’t end up with flat spots when you removethe sprue. Sand the inside with a sanding cartridge. The coarser the sand paper, the harder it will be to remove the scratches (keep that in mind). Remove the sprue, using a diamond wheel or belt sander, again the coarser the tool the harder it is to remove the scratches. Use a deburring wheel or a buff stick to smooth the surface, and remove any rough scratches. By using several grits, and stepping up the grit will make polishing that much easier.

working with platinum polishing
working with platinum polishing

Now that the shank is prepped, let’s get started on the head area. Remove all unwanted surfaces on the head using a rubber wheel and/or bullet rubber wheel in the areas that are easy to get to without changing the shape of the prongs or the bearing. You may have some rough texture that you’ll need to work with a ceramic stone. I use an ultrasonic polisher for this, but if that’s not an option you can use a pin vise to hold the ceramic stone. Once you have removed all the rough surface with the ceramic stone go over that area with radial bristles, start with the red radial bristle than go to the blue radial bristle. This will make head polishing a lot quicker.

 

Now, let’s work the gallery. Thrumming in the gallery can create a high polish just as beautiful as the rest of the piece. For this, you can use precut slurry sheets in different grits or a platinum sand paper in the different grits (make sure to cut the strips to fit the gallery opening).

Time to Polish

Let’s start polishing! You’ll polish the head area first using a soft mm, geza brush, or end brush and the luxor red polish. The luxor red is an aggressive polish, so you want to be careful not to over polish. Then you will polish the inside, using an inside felt polisher and the luxor red. Polish all scratches out (if you’ve taken the necessary steps with the sand paper cartridges this should go quick). Then you will polish the outside of the shank with a hard buff using a firm stitched buff and the luxor red, then follow with the Avivor polish. Lap the sides of the shank with a lap machine or a knife edge felt wheel (this looks like a felt rubber wheel) using a flex shaft and the luxor red again. Now let’s final buff. For this you will need a soft muslin buff and Avivor or Oras polishing compound. Polish the entire piece until all scratches have been removed. Make sure to work the head, sides and shank to a high polish.

When Soldering

Use safety precautions to protect your eyes, by using a #5 or #6 rated welding safety glasses should keep you safe from damaging your eyes while soldering on platinum. When soldering platinum it is very important not to contaminate the platinum. Always make sure the piece is clean of any oils, dirt and polish before soldering, and by keeping separate tools used solely for platinum (solder pads, ceramic tweezers, tungsten picks, etc).

working with platinum soldering

It’s also important to note that it is not recommended to use boric acid mixture or flux when soldering platinum. For assembling a head to a shank a 1500 C repair solder is recommended, soldering a peg head to a shank or an earring post to an earring a 1200 C repair solder is recommended, for sizing a 1700C solder has the best color match and there is less of a chance of solder erosion. Use natural gas/oxygen, propane gas/oxygen or hydrogen/oxygen when soldering platinum. When using a water torch make sure to disable the water feature on the torch. Do not use Acetylene gas when soldering platinum, it’s the dirtiest of all the gases and full of contaminants. Now that you have soldered your piece finish the platinum with the steps from above.

Tools & supplies for working with platinum

Flat 1200 Grit Red Ceramic Stone

        21-1205          1200 Grit Ceramic Stone

Aluminum File Handle 4"

      37-8790        Ceramic Stone Holder

        11-6063            Blue Medium Flex Rubber Wheel

     35-1234       Sheenus Neo Ultrasonic Polisher

White Knife-Edge Silicone Pre-Polish Wheels 7/8"x1/4" - Pack of 10

        11-8140          Knife-Edge Polish Wheels

3M® Radial Bristle Yellow Disc 3/4"

        10-9100, 10-9101              10-9102              Yellow, red, blue radial bristles

Polishing Cloth Strip Assortment 216 Sheets

       10-8343      Polishing strips

18-0516, 18-0518 Tungsten-Carbide Burnishers

3M® Tri-Mite Pre-Cut™ Abrasive Paper 500 Grit (20 Micron)

       11-0747            3M® Tri-Mite Abrasive Paper 400 or 500 Grit

       47-3224           Luxor Red Polish

Soft Miniature Mounted Brush 5/8" OD, 3/32" Shank

    16-7050, 16-7051   Soft White MM or End brushes

Merard AVIVOR Polishing Compound

          47-3223         Avivor Polishing Compound

Yellow Treated Muslin Wheel Buff, 5", 3 Row, 60 Ply

         17-5560          Yellow buff

       47-3224           Luxor Yellow Polish

Purple Treated Muslin Buff, 5", 3 Row, 40 Ply

         17-7253          Purple Buff

Merard ORAS Polishing Compound

       47-3225           ORAS Polishing Compound

Finex Combed Muslin Buffs with Leather Center 5" / 50 Ply

         17-7722          Finex Muslin buff

10-6091, 10-6094     320 & 800 Grit Cartridge Rolls

      11-8182      Silicone Inside Ring Cylinder

Abrasive Board Kit

      11-3430       Abrasive Board Kit


Do you have any tips for working with platinum? Tell us in the comments section below.




Sizing A Channel Set Mounting

Have you ever experienced the nightmare of sizing down a channel set mounting that has already been set, with the channel running across the shank (see illustration 1)? If so, you may have also experienced the stones falling out or becoming loose. Though this problem does not exist with all channel set mountings, the following tips may help you avoid having to reset or replace a stone.

HELPFUL HINTS:

  1. Cut out the amount needed to size the ring down to required size at the bottom of the shank, leaving the shank open.
  2. Saw completely through the bottom bearing of the head (see illustration 1).
  3. Saw halfway through the top bearing.
  • You may need to bevel the bottom bearing depending on how many sizes the ring has to go down. This allows the shank to bend in from the top.
  • If the ring is solid (see illustration 2 & 3) saw two-thirds of the way through and slightly bevel the saw cut to allow for movement of the ring during the bending process.
  1. Now you can bend the shank in from the shoulders to fit flush. Solder the shank back together at the bottom, then fuse with torch or laser the relief cuts you sawed. The ring will appear slightly egg shaped, so you may not want to round it out completely.
  2. Finish the piece as you normally would. You may need to tighten stones, but the process will keep stones from falling out of their seats/ or breaking.

Another problem you may come across is sizing a ring up that has already been channel set. This creates a completely different problem. Sometimes when sizing up more than one size you may chip or break the stones.

This does not happen with all channel set mountings, but unfortunately it can happen, especially if the stones are close together or if they touch one another. A good example of this is the mounting shown below (see illustration 4). This particular ring needed to be sized from a size 10 to a size 12. All of the stones were touching one another.

ring

Illustration 1

illustration2

Illustration 2

illustration3

Illustration 3

Illustration 4

HELPFUL HINTS:

  1. Saw the shank at the bottom, then saw a relief cut on the inside at the top of mounting (see illustration 4). Slide the ring onto a mandrel, pull the ring down the mandrel with your fingers to a size 11 ¼ being careful of stones. It is not a good idea to go up all at once. This can put too much pressure on the stones and cause stress on the mounting (see illustration 5).
  2. Use a piece of flat or square sizing stock twice the thickness of the shank, you will be hammering it up the rest of the way (see illustration 4). Place sizing stock flush against the opening of the shank, and try to get it flush on the inside of the shank.
  3. Solder your stock in place with hard solder. Let ring air cool. If the shank is not flush on the inside, you will need to remove the excess stock until the inside of the shank is flush. If the shank and stock are not close to being flush, the ring can pop open at the solder joint when hammering the ring up.
  4. Slide the ring onto the mandrel. Round it out slowly to avoid breaking stones. It is important you do not try to round out the top of ring flush with mandrel (see illustration 4). Once you have rounded the ring at the bottom, start hammering on sizing stock with a metal hammer until you have reached the size you need. When hammering up you will need to flip the ring on the mandrel to each side so your shank will stretch evenly. You may also want to leave the shank slightly oval if sizing up more than 1 ½ to 2 sizes. It will be much safer for the stones and place less stress on the mounting.
  5. Once you have reached the size you need, file excess metal off the sides and file top of plug even with shank. By now your plug has been hammered close to the thickness of the shank with a little filing on the outside. File evenly, then finish your ring as you normally would.

Illustration 4

Illustration 5

*It is important to note that increasing/decreasing the size will change the circumference and getting the ring completely round may not be an option.

Do you have any sizing tips? Tell us, in the comments section below.