Surface treatment
Substrate
Introduction
The purpose of carrying out surface preparation on non-ferrous substrates is more or less same as for treating carbon steel:
- To remove contamination
- To create a surface profile
A passive layer (oxide film) will develop on non-ferrous alloys and can interfere with adhesion between the paint and the substrate
A wash primer (etch primer) is sometimes used if thorough cleaning and abrasion is not possible
- Control of the DFT of Etch Primers is crucial as excessive thickness could result in adhesion problems of the next coat due to acid residue on the surface of the etch primer
Common non-ferrous metallic substrates:
- Stainless steel
- Aluminium and its alloys
- Copper and its alloys
- Zinc and its alloys (hot dip galvanizing)
Reasons to apply paint:
- Improve corrosion protection
- Decoration
- Signage or Identification
Aluminium & Stainless Steel surface preparation
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Corrosivity of the environment |
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Light corrosivity |
Moderate corrosivity |
Heavy corrosivity |
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Degreasing with alkaline detergent and fresh water rinsing followed by: |
Degreasing with alkaline detergent and fresh water rinsing followed by: |
Degreasing with alkaline detergent and fresh water rinsing followed by: |
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Light abrading |
Hand or machine abrading |
Hand or machine abrading OR Brush blasting with non-metallic abrasives |
Copper and its alloys surface preparation
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Corrosivity of the environment |
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|
Light corrosivity |
Moderate corrosivity |
Heavy corrosivity |
|
Degreasing with alkaline detergent and fresh water rinsing followed by: |
Degreasing with alkaline detergent and fresh water rinsing followed by: |
Degreasing with alkaline detergent and fresh water rinsing followed by: |
|
Light abrading |
Hand or machine abrading |
Hand or machine abrading OR Brush blasting with non-metallic abrasives |
Zinc surface preparation
|
Corrosivity of the environment |
||
|
Light corrosivity |
Moderate corrosivity |
Heavy corrosivity |
|
Degreasing with alkaline detergent and fresh water rinsing followed by: |
Degreasing with alkaline detergent and fresh water rinsing followed by: |
Degreasing with alkaline detergent and fresh water rinsing followed by: |
|
Light abrading OR Weathering (for at least 12 months) then degrease, rinse and light abrade |
Hand or machine abrading OR Weathering (for at least 12 months) then degrease, rinse and light abrade |
Hand or machine abrading OR Brush blasting with non-metallic abrasives OR Weathering (for at least 12 months) then degrease, rinse and hand or machine abrade |
