Surface Finishes and Textures

Injection mold surface finishes

All parts have a surface texture resulting from the injection mold that produced them.  Make sure to specify the desired finish you want before the start of mold production.

The Plastics Industry Association (PIA) is an independent trade organization in the USA that has created standards for surface finishes on injection molds.  They were previously known as SPI, or Society of Plastics Industry.

Standard PIA / SPI mold surface finishes are listed in this table.  Other texturing options such as Mold-Tech or VDI can also be utilized as references for mold finishes to provide the desired surface texture on your part.

A surface finish spec does affect mold cost. A-1 is the most expensive finish due to all the time and effort it takes to achieve.  Texturing cost decreases as you move down the table from A-1.

If left unspecified, SPI B-2 is our standard non-gloss surface finish.  SPI A-3 is what we typically use for a glossy finish.

PIA/SPI StandardFinishFinishing MethodTypical Surface Roughness Ra (um)
A-1Super High GlossyGrade #3, 6000 Grit Diamond Buff0.012 - 0.025
A-2High GlossyGrade #6, 3000 Grit Diamond Buff0.025 - 0.05
A-3Normal GlossyGrade #15, 1200 Grit Diamond Buff0.05 - 0.10
B-1Fine Semi-Glossy600 Grit Paper0.05 - 0.10
B-2Medium Semi-Glossy400 Grit Paper0.10 - 0.15
B-3Normal Semi-Glossy320 Grit Paper0.28 - 0.32
C-1Fine Matte600 Grit Stone0.35 - 0.40
C-2Medium Matte400 Grit Stone0.45 - 0.55
C-3Normal Matte320 Grit Stone0.63 - 0.70
D-1Satin TexturedDry Blast Glass Bead #110.80 - 1.0
D-2Dull TexturedDry Blast #240 Oxide1.00 - 2.80
D-3Rough TexturedDry Blast #24 Oxide3.20 - 18.0


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