Surface Finishing

The exposed surface area of aluminium extrusion is inherently protected by a naturally occurring, transparent layer of aluminium oxide. This barrier layer forms immediately the newly extruded aluminium is exposed to oxygen and is referred to as 'mill' finish. In many instances, this finish may not be suitable for the product's final application. Where additional surface protection and/or colour is required, G.James offers both anodised and powder coated finishing as part of our complete service package.

Powder Coating

Powder coating is an electrostatic process where fine paint particles are sprayed onto the surface of pre-treated aluminium. In a similar way that iron filings attract to a magnet, the coloured powder adheres to the aluminium coating surface due to the electrostatic effect. Once the powder is applied, the aluminium is then baked in an oven to achieve a highly durable, painted finish.

G.James undertakes an extensive, chromate conversion pre-treatment process prior to the application of the powder ensuring an improved level of corrosion resistance for the base aluminium surface.

G.James is a Dulux and Akzo Nobel approved applicator offering a selection of standard and high durability grade powders in an extensive range of colours, gloss levels and metallic shades.

We are also a licensed applicator of the Effecta process which replicates the colour and appearance of timber grain onto flat-faced aluminium profiles.

Powder Coating Benefits & Characteristics:

Extensive colour range
Excludes extrusion die lines
Small scratch marks can be repaired (touch-up process)
Powder coating is an efficient and economical process

Anodising

Anodising is electrochemical ‘conversion’ process that enhances the metallic lustre of aluminium and thickens the surface layer of aluminium oxide. This controlled oxidisation forms a much harder, more corrosion resistant surface finish. For additional protection, G.James implements a ‘hot-seal’ application to the final stages of anodising to prevent any possibility of fading or cracking. See diagram below.

We offer clear anodised and the full-colour spectrum from light bronze through to black, in thicknesses ranging from AA10 micron, up to AA25 micron. Upon request, G.James can also apply a ‘media blast’ process that produces a highly uniform, blemish-free, matte finish.

Anodising Benefits:

Best finish for resisting corrosion in coastal and high salt environments
Exhibits subtle change in appearance in different light & angles
Is an integral finish with a high level of colour fastness and surface durability (for resistance against UV degradation, abrasion and heat)
Does not outgas or deposit stains on the glass when used in high temperature and/or shadow box applications
Optimal surface coverage
No risk of adhesion failure

Anodising Characteristics:

Finishes are subject to colour variation due to differing alloy compositions within the extrusion
Extrusion die lines can be visible particularly on wider surfaces. These lines can be eliminated prior to anodising with G.James’ media blast process
While durable & hard to scratch when damage occurs it is difficult to repair

Comparison Table

	Anodising	Standard Grade Powder Coat	Extra High Durability Powder Coat	PVF Fluorocarbon Powder Coat
Composition	Electro deposit	Thermoset Polyester	Thermoset Polyester	Fluoro Polymer Resin
Colour Range	Clear and light bronze through to black	As per manufacturer's colour cards	Limited range, made to order colours available	Limited range, made to order colours available
Colour Variation	Some (dependant on alloy, and angle & intensity of light)	Little variation with solid colours. Some variation possible with metallic & bright colours	Little variation with solid colours. Some variation possible with metallic & bright colours	Little variation with solid colours. Some variation possible with metallic & bright colours
Gloss Range	20 – 90	10 – 80	10 – 80	25 – 60
Scuff / Impact Resistance ¹	Excellent	Good	Good ³	Very Good
Flexibility ²	Fair	Good	Good ³	Good
Years to First Chalk	10 years	3 - 5 years ⁴	5 - 10 years	10 - 15 years
Mortar Stain	Yes	Possible	Possible	Possible
Service Life (Guide Only)	15 - 20 years	10 years	15 - 20 years	20+ years
Coating Thickness (Microns)	10, 15, 20 or 25	60 – 80	60 – 80	50 – 80
Pre-treatment	Caustic etch or Polish	Chromate	Chromate	Chromate
Touch Up	No	Yes	Yes	Yes
Relevant Standard & Specification	AS 1231	AS 3715	AS 3715	AAMA 605.3
Warranty	10 years on request ⁶	No	10 years on request ⁶	10 years on request ⁶
Applications	Housing, residential, commercial & monumental	Housing & Residential	Residential & commercial buildings	Monumental buildings and shading systems

Notes: ¹ Resistance to minor damage during transport (rubbing) and general handling/processing. Excludes scratches. ² Suitability for folding and rolling post-finishing, particularly relevant for aluminium sheet for flashings etc. ³ Electro and Precious colours are not recommended if post finish fabrication (eg. rolling, folding, bending etc.) is required. ⁴ For bright colours (ie. those with high levels of colour pigment) this time is likely to be less. Compliance with the G.James Care & Maintenance Instructions is recommended to reduce the likelihood of chalking. ⁵ Will stain if long-term exposure occurs. Remove and clean any mortar on aluminium surfaces as soon as it is noticed. Refer to the G.James Care & Maintenance Instructions leaflet. ⁶ Warranties exceeding these terms, as promoted by Dulux and Interpon (being Suppliers), are issued from the supplier to G.James (being the Applicator) and as such the terms and conditions are not relevant or transferable to the customer. A copy of the Supplier's warranty (to G.James) is available upon request for the purposes of confirming the application of the powder specified and in no way transfers an extended warranty term to the customer.