Guide to powder coating

Guide Lines For Pretreatment

Aluminum Yellow  Chromating

1. Clean 5.0 – 10.0 minutes 60°C- 70°C    
2. Rinse 1.0 – 2.0 minutes room temperature
3. Etching 0.5 – 1.0 minutes 60°C
4. Rinse 1.0 – 2.0 minutes room temperature
5. Deoxidizing 0.5 – 1.0 minutes room temperature
6. Rinse 1.0 – 2.0 minutes room temperature
7. Yellow Chromate 1.0 – 2.0 minutes 20°C
8. Rinse 1.0 – 2.0 minutes room temperature
9. DI Rinse 0.5 minutes 40°C- 50°C

COMMENT

  • Coating weight should be between 30-100 milligrams pers sq.ft.
  • Dry-off with warm blowing air at a temperature of 90°C
  • The degreasing step will remove only a fresh light coat of white rust
  • The etching step is required to remove heavier coats of white rust.
  • The chemical supplier should be consulted for optimum time and temperature

 

Aluminum Green Chromate

1. Clean 5.0 – 10.0 minutes 60°C- 70°C 
2. Rinse 1.0 – 2.0 minutes room temperature
3. Etching 0.5 – 1.0 minutes 60°C 
4. Rinse 1.0 – 2.0 minutes room temperature
5. Deoxidizing 0.5 – 1.0 minutes room temperature
6. Rinse 1.0 – 2.0 minutes room temperature
7. Green Chromate 1.0 – 2.0 minutes 20°C
8. Rinse 1.0 – 2.0 minutes room temperature
9. DI Rinse 0.5 minutes 40°C- 50°C

COMMENT

  • Coating weight should be between 30-250 milligrams per sq.ft.

 

Galvanized steel    Transparent Chromate

1. Clean 5.0 – 10.0 minutes 60°C- 70°C 
2. Rinse 1.0 – 2.0 minutes room temperature
3. Etching 0.5 – 1.0 minutes room temperature
4. Rinse 1.0 – 2.0 minutes room temperature
5. Deoxidizing 0.5 – 1.0 minutes room temperature
6. Rinse 1.0 – 2.0 minutes room temperature
7. Transparent Chromate 1.0 – 2.0 minutes 20°C
8. Rinse 1.0 – 2.0 minutes room temperature
9. DI Rinse 0.5 minutes 40°C- 50°C

COMMENT

  • Chromating is the best pretreatment for Galvanized steel. Transparent Chromating has proved to be the best for this purpose.

 

Remark

  • Outdoor use of steel requires an excellent pretreatment because steel is highly corrosive.
  • We recommend two types of pretreatment; Zinc phosphate or Iron phosphate.
  • Zinc phosphate is used for automobiles and arhitectural products.