SPI A2 finish
Higher gloss alternative.
SPI A2 finishGlossary
What Is an SPI B1 Finish? Injection Molding Explained
SPI B1 is a medium gloss polish band between high gloss A grades and matte C grades.
Glossary
SPI B1 is a medium gloss finish from fine abrasive polish
B grades reduce glare compared with A grades while staying smoother than stone C grades.
B1 reads as satin high gloss on many engineering resins. It hides minor flow witness better than mirror A grades on some geometries.
Tooling still needs defined shutoffs when B1 faces meet textured C or D regions.
Process windows for pack and venting remain important even when gloss is moderated.
Appearance
When B1 fits product styling
Match the SPI band to how the part is viewed in use.
- Handheld devices viewed under office lighting rather than spotlights
- Large flat covers where mirror glare is undesirable
- Parts that will receive paint where minor steel texture is acceptable
Go deeper
Where this term connects
Each link is a different angle on the same program, not a duplicate definition.
SPI C1 finish
Fine stone matte band.
SPI C1 finishMatte finish spoke
Broader matte programs.
Matte finish spokeMoldTech texture
Etched grain versus SPI polish.
MoldTech textureVisual reference
Photos from molding and tooling programs
Images are selected from the NetProto Forge media library for this topic.
Injection molded production parts on a tray
Injection molded production parts on a tray
Engineer reviewing a molded part drawing
Engineer reviewing a molded part drawing
Plastic housing components from a steel tool
Plastic housing components from a steel tool
FAQ
SPI B1 questions
Can I specify B1 on one face only?
Yes when the mold includes mixed finish shutoffs.
Does B1 eliminate gate vestige?
No. Vestige still trims or hides per gate style.
How does B1 compare to VDI texture?
SPI B1 is polish gloss. VDI numbers describe etched texture depth.
Next step
Pick finish before steel polish
Upload CAD with per face SPI or texture notes for DFM review.