Over 50 Years in Business

50+ years of exceptional quality.

Precision Custom Molding and Manufacturing

Aerospace, Military, Energy, Transportation, Critical OEM

AS9100D Certified

  A Woman Owned Small Business

SPI Mold Finish Standards

The SPI mold finish ratings allow you to specify a general mold surface finish.   The finish is a call-out on the mold itself, not on the finished product as the final part finish will vary with processing, plastic material, mold quality and mold steel.  If you need exact texture matching of plastic parts then a more detailed standard is required. 

High Quality, Optical Quality
  • SPI Finish A-1 — Grade #3, 6000 Grit Diamond Buff
  • SPI Finish A-2 — Grade #6, 3000 Grit Diamond Buff
  • SPI Finish A-3 — Grade #15, 1200 Grit Diamond Buff
  • SPI Finish B-1 — 600 Grit Paper
  • SPI Finish B-2 — 400 Grit Paper
  • SPI Finish B-3 — 320 Grit Paper
Non-Cosmetic, Stone Polish
  • SPI Finish C-1 — 600 Grit Stone
  • SPI Finish C-2 — 400 Grit Stone
  • SPI Finish C-3 — 320 Grit Stone
Non-Cosmetic, Dry Blast, Matte Finish
  • SPI Finish D-1 — 600 Stone Prior to Dry Blast Glass Bead #11
  • SPI Finish D-2 — 400 Stone Prior to Dry Blast #240 Oxide
  • SPI Finish D-3 — 320 Stone Prior to Dry Blast #24 Oxide

Finish requirements can add to the mold and part costs and typically add 1-2 weeks to tooling build time (See: Tooling Schedules).   Mold finish is often overlooked but it is quite important to discuss during the quoting and mold building process.


Mold Textures

Mold textures are another method of calling out the finish for a molded part.  Textures can be photo-etched using patterns or chemically etched.  We will cover textures in a future post.