Jeff Mathews has developed a process for polishing the inside of platinum rings using 3M™ abrasive technology. To illustrate how he performs the job, I follow his procedures using this hand fabricated flat platinum band. Tool and forming marks are easily visible. The quality and identification marking has been completed.
Finishing the Inside of a Platinum Ring
After welding the ring and rounding it, I use several grades of 3M™ Imperial Micro-Finishing film adhered to a sheet of glass to true and pre-finish the sides of the ring band.
For the inside of the ring, Mathews advises using a 3M™ Trizact abrasive band of A80 grade grit mounted on a drum arbor mandrel. The 3M grit identification system is unique to their products and A80 is equivalent to 220 grit. 3M™ Trizact abrasive products feature a surface composed of tiny pyramid-shaped aluminum oxide abrasives in several grits that uniformly and evenly remove material. The Trizact band worked quickly and uniformly, and it did not remove a noticeable amount from the surface. Often with traditionally used sand papers, the abrasive âpebbleâ will break away from the paper and will introduce newer deep scratches to your work. Trizact technology eliminates this concern.
Next Mathews advises using three grades of 3M™ M10 Flex Diamond bands. The flex diamond bands are metal bonded. They remove material evenly and efficiently. He uses grits equivalent to 800, 1,800 and 3,000. To lubricate this part of the process, Mathews uses Bur-Life. When starting with a new flex band, Mathews first dresses down the resin surface coating. He’s used the same flex diamond bands routinely for over a year and is impressed with how long they last.
Next he advises using 5 grades of 3M™ Imperial Micro-Finishing Film. He cuts the strips in 1/2 inch widths and wraps them over a diamond flex band mounted on an arbor mandrel. The flex band provides a hard flat backing for the adhesive backed micro-finishing film. The 5 grades of film I used are listed according to their grit and color were: #1) 400 (green), #2) 600 (orange), #3) 1,200 (blue), #4) 2,500 (lavender) #5) 3,500 (gray). Shown here is the use of the 400 grit, the first step in the pre-finishing process. In this photo I’m using the 400 grit micro-finishing film that is step #1 in the process.
Here I’m using the 1200 grit micro-finishing film that is step #3 in the process. Notice the improving luster and how smooth it’s becoming.
For the last steps, Mathew’s advises using 3M™ Diamond Lapping Film with a grade of 3 microns (pink) then buffing it with Foredom’s White Platinum rouge (6,000).
The result of this progressive process were superior. The inside ring is flat, even and highly polished. The surface was hardly reduced in dimension and the quality marks remain easily visible and were not distorted. This process would also be ideal for bi-color shanks of platinum and gold alloys as it would evenly work with both alloys.