ForMatter/Finishes/polish/Electropolish
finish_polish_electro

Electropolish

polish · mirror · electrochemical polish, EP, anodic dissolution

Polish without an abrasive — submerge the part in an acid bath, run current through it, and the high points dissolve faster than the low points. Surface emerges smoother, brighter, and microscopically deburred. Standard for medical implants, food-grade tanks, semiconductor chambers.

Anodic electrochemical dissolution in a phosphoric/sulfuric acid mix at controlled current density (~10–20 A/dm²) and temperature (50–70 °C). Removes ~10–25 µm of surface material; preferentially attacks asperities, leaves valleys. Typical Ra reduction ~50% of starting value. Passivates stainless simultaneously (chrome-rich oxide layer thickens), so often spec'd for 316L medical / pharma where corrosion resistance and cleanability matter as much as cosmetic shine.

character — mirror-bright with no directional grain, slightly soft / wet read, sterile.

Finish properties

  • levelmirror
  • subcategoryelectrochemical
  • Ra (µm)0.1
  • applies tometal

Second life

reversibilitymoderate — a polished surface can be re-roughened (sandblast, brush, etch) and a roughened surface can be re-polished; the substrate is preserved unless polishing-induced material loss is significant.
blocks substrate recyclingno
renewabilityvery high — polishing is the canonical maintenance operation for almost any hard surface; field-renewability is high for accessible surfaces, shop-renewability for everything else.

ASM Handbook Vol. 5 Surface Engineering; manufacturer abrasives literature (3M, Norton, Mirka).

Citations