Table 1 Temperature, operation time and used chemical in all the processes.

Degreasing

45–55

30–90

Na₂CO₃, Na₃PO₄, NaC₂HCl₃, C₂Cl₄

Etching & Neutralization

55–65

30–60

NaOH, H₂SO₄, HF, HNO₃

Soft anodizing_1*

21–27

2,400–2,700

H₂SO₄, Al₂O₃

Soft anodizing_2**

21–27

2,400–2,700

H₂SO₄, Al₂O₃

Hard anodizing_1*

− 4–4

312–432

H₂SO₄, Al₂O₃

Hard anodizing_2**

− 4–4

312–432

H₂SO₄, Al₂O₃

Chromium plating

65–75

600–720

H₂SO₄, H₂CrO₄

Coloring 1*

40–60

600–720

Azo

Coloring 2**

40–60

600–720

Azo

Sealing

65–75

420–780

C₂H₃NaO₂ (12%), Ni(CH₃CO₂)₂ (5%)

Polishing

100–120

60–180

H₂SO₄, HNO₃, Al₂O₃, H₂CrO₄

Non-polishing

45–55

60–90

H₂SO₄, HNO₃, Al₂O₃, H₂CrO₄

Chromium cleaning

21–27

180–300

CH₂Cl₂