ForMatter/Finishes/mold_finish/SPI C1 (stone finish, 600-grit stone)
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SPI C1 (stone finish, 600-grit stone)

mold_finish · matte · SPI C-1, matte mold finish (stone)

Mold cavity finished with a 600-grit oilstone — the molded part comes out with a low-gloss, slightly soft matte. Good for mid-tier consumer-product finishes, the inside of food-grade containers, parts that get printed or labeled. Hides flow lines that an A or B finish would expose.

SPI / SPE finish C1 — 600-grit oilstone polish on tool-steel cavity. Surface roughness Ra ~0.4 µm. C2 is 400-grit oilstone (Ra ~0.6); C3 is 320-grit (Ra ~0.8). All C-series are matte; the stone leaves a slight directional read that breaks specular reflection. Hides cosmetic defects (flow lines, knit lines, minor sink) better than B-series; lower mold cost; the workhorse non-cosmetic mold finish.

character — low matte, soft, hides defects, neutral reading.

Finish properties

  • levelmatte
  • subcategorySPI / SPE stone finish
  • Ra (µm)0.4
  • applies topolymer
Produced by processesInjection Molding

Second life

reversibilityzero on the molded part — the mold-cavity surface is transferred at the moment of forming and cannot be undone without re-molding from a different cavity.
blocks substrate recyclingno
renewabilityzero on the existing part; the mold cavity itself can be re-polished or re-textured by the toolmaker for subsequent runs.

SPI / SPE Mold Surface Finish standards (A-1 through D-3); VDI 3400 mold-cavity texture reference plates.

Citations

  • standard · SPI/SPE Mold Finish Standards (Society of the Plastics Industry, AB-3) — C1 / C2 / C3 stone-finish reference.