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Generally the oxidation
layer on aluminium is dense, stable and is suitable for painting after
careful cleaning to remove other contaminants. Sometimes however, aluminium
can be prone to 'filigree' corrosion and/or pitting. In these cases
the surface must be abraded to bright metal using fine wet and dry paper.
Several chemical preparations are available for cleaning aluminium.
Should such a product be used it is imperative that all residues are
rinsed off before painting.
- Wash and clean surfaces:
Mix one part of Resene
Roof Wash and Paint Cleaner with three parts of fresh water. Apply
a liberal wash of this mixture to the surface with a nylon bristle
brush or broom. Thoroughly scrub the surface to ensure complete removal
of all grease, dirt, dust and other contaminants. Rinse thoroughly
with fresh water and allow to dry.
- Wet and dry sand:
Thoroughly wet and dry sand to remove any areas of corrosion. Any
pitted areas should be wet sanded to a smooth profile. Round off any
sharp edges on the aluminium profile to allow better film build.
NB. Possible corrosion may occur at mitred joints in aluminium where
the cut edges are unprimed. This coating system may not provide protection
for these areas.
First coat:
Apply one coat of Resene
Vinyl Etch at between 7-12 square metres per litre.
If the surface you propose to paint is already painted and in good
condition, then you can go straight to the 'Second/Third coat' below.
Topcoats:
Apply two coats of either
Resene
Enamacryl (gloss) or Lustacryl
(semi-gloss) - waterbased enamels at approximately 12 square metres per
litre.These products perform like solventbased paints with the added benefits
of non-yellowing, fast drying and low odour when compared to solventbased
paint.
Follow label instructions at all times.
Cleaning up:
Cleaning up waterbased paints is different to solventbased
paints - click here for detailed instructions
on clean up.
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