-
An SPI A-1 Diamond Finish is a specialty of Bales Mold Service. We use it to produce the finest finish on molds, producing highly visible or lens quality parts. The SPI A-2 is the most widely used diamond finish, providing good release and good visual parts. An SPI A-3 is a fine choice for release where a high gloss appearance is not required. All diamond finishes work well with chrome and nickel.

- Paper Finishes, SPI B-1 to B-3 – Next to diamond polishing, paper finishes are the second most refined finishes available. Paper finishes produce a slightly reflective or glossy shine and very good release. They are often recommended for products that do not require a big decorative or visual impact.
- Stone Finishes, SPI C-1 to C-3 – The most economical finish, stone finishes are also the first step in the process of creating both the paper and diamond finishes. Stone finishes provide good release but very little gloss to the plastic part. This is a good choice for strictly functional molded parts where aesthetics are of no importance.
- Blast Finishes, SPI D-1 to D-3 – When done properly, blasted finishes can produce some of the most interesting stipples and textures on mold surfaces. From a fine satin texture with varied degrees of gloss to a flat, no-gloss coarse stipple, Bales has the blast media to produce the proper finish for you. Blast finishes are also an excellent way to camouflage weld repairs and slight imperfections.
Specifications
| Types of Finishes | Current SPI Finish Numbers | Description and Previous Finish Numbers | Roughness Comparison R.A. | ||
| Diamond | #3 Diamond Buff | A1 | is comparable to | #1 | 0-1 |
| #6 Diamond Buff | A2 | is slightly finer than | #2 | 1-2 | |
| #15 Diamond Buff | A3 | has more imperfections than | 2-3 | ||
| Paper | 600 Grit | B1 | is finer than | #3 | 2-3 |
| 400 Grit | B2 | is slightly finer than | 4-5 | ||
| 320 Grit | B3 | is comparable to | 9-10 | ||
| Stone | 600 Stone | C1 | is finer than | #4 | 10-12 |
| 400 Stone | C2 | is slightly finer than | 25-28 | ||
| 320 Stone | C3 | is comparable to | 38-42 | ||
| Dry Blasted | #11 Glass Bead | D1 | is finer than | #5 | 10-12 |
| 240 Aluminum Oxide Blast | D2 | is comparable to | 26-32 | ||
| #24 Aluminum Oxide Blast | D3 | is a little more coarse than | 190-230 | ||