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Anodising - The Process

Aluminium corrodes when exposed to the atmosphere, forming a natural oxide, as with other metals such as steel. The oxide is an integral part of the base metal. Anodising is a process that controls the oxidation, by rapidly growing an extremely hard skin which prevents further oxidation. This is achieved by electrolytic immersion, after which the anodised component can be sealed to close the pores of the oxide layer and provide maximum corrosion resistance.

Anodising Advantages

Anodising is consistently cheaper than powder coating, offering savings in the region of 20-60%.

When making comparisons ensure that:

  • The same warranty period is used for comparison ie 25 or 35 years.
  • The Pre-Treatment process (ePrime) is included by the powder coater, in order to satisfy the warranty requirements.
  • See AWA Product offerings and price comparisons.

Warranty Period:

  • 25year – Anodising is UV resistant, so does not fade, and that is why anodising offers up to 25years ‘Colour’ warranty, for a standard ‘Durable’ finish compared to 15-20 years, offered by powder coating.
  • 35 year – Extreme atmospheric conditions such as salt spray do not threaten anodising film either and so AWA is able to offer up to 35 years warranty for ‘Surface’ Integrity which can only be matched by very expensive, ‘ultra-durable’ powder coat finishes. 

Lustre – The anodised layer is a translucent finish which glistens, as it reflects the beauty of the base metal. It is a unique finish that cannot be replicated by ‘deposit’ finishes such as wet spray or powder coating.

 

A Complete Homogeneous Finish – The oxide is able to be grown as an integral part of the base metal which is a very important benefit.  Anodised aluminium will not peel, flake or pit, unlike comparative finishes that are deposited onto the metal.  As anodising is an immersion process the continuity of film is maintained throughout the perimeter of the product, unlike a sprayed finish >> See. Consistent Coverage – Edge Pull

 

Hardness – A major advantage of the anodised layer is in the hardness of the film achieved, which is close to diamond on the Mineral Hardness Scale, and offers maximum wear resistance, which is the reason why many household appliances are anodised.

 

Longevity – Once sealed, the anodised layer is impervious to weathering and so longevity is clearly a major advantage which impacts on Life Cycle Analysis (LCA) as well as the reduced costs associated with routine maintenance.

Colour Range

Standard Colours (Natural, Bronzes and Black)

Suited for all applications

Sterling

Carrara

Quicksand

Di Sierra

Bistre

Massimo

Millbrook

Mikado

Eternity

Gold Dye Colouring (Absorption Dye Process)

Suited for limited application - contact AWA for more information

Sahara

Manhattan

Colour Matching

Please consult Anodisers WA for colours outside this range
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Order your sample box today

Performance Options:

Large Residential & Commercial: 100+ tonnes

Standard

25 Year Warranty

Surface Integrity/No Colour Loss

AS1231 – 2000

AA20UM

High Performance

35 Year Warranty

Surface Integrity / No Colour Loss

AS1231 – 2000

AA25UM

How To Specify

Standard 25 Year Warranty

Anodisers Warranty Microns Finish
Anodisers WA Exterior Smart AA2OUM Sterling

High Performance 35 Year Warranty

Anodisers Warranty Microns Finish
Anodisers WA Exterior Plus AA25UM Sterling

Specifying Sheet Metal

Please refer to design factors for aluminium sourcing guide

Comparing Surface Finishing

Anodisers WA 2021 Price Comparison

January 2021 Anodisers WA undertook a price comparison with three Western Australia Powder coaters. A combination of 48 extrusions and panels were priced When Comparing Standard Warranty Aluminium Finishing to a registered warranty applicator

Comparing Durable Exterior Smart AA2oUM

Comparing Ultra Durable Exterior Plus

Warranty

Understanding the performance differences for your next warranty project

Key Factors affecting Warranty
Surface Integrity Colour Maintenance
Anodising Anodising can not crack, chip, peel or flake Not Affected by UV
Warranty a limiting a degree of fading
Cleaning
3 Months Marine/Industrial
6 months Coastal
12 Months - Metro
Powdercoating Can crack, peel, flake and chip Can be affacted by UV
Warranty a limiting a degree of fading
Cleaning
3 months Marine/Industial
6 Months Caostal
12 Months - Metro

Standard Durable Warranty

Surface Integrity Colour
Exterior Smart 25 25
Dulux Electro 25 15
Dulux Duratec 25 20
Interpon Ultriva/D2015 20 15
Interpon D2525 25 15

High Performance Ultra Durable

Surface Integrity Colour
Exterior Plus 35 35
Dulux Flouroset 35 30
Interpon Fluormax/D3020 30 20

Green Finishing

Anodsing uses up to 51% less energy and emits 38% less green house gas when compared to powdercoating.

Energy Consumption

Production of 1 Tonne of surface finished aluminium 100 year life cycle – Kwh per tone of aluminium

GHG Footprint

Production of 1 Tonne of surface finished alumnium 100 year life Cycle-tCO2 per tonne of aluminium produced

Environmental Impact

Measure the impact of your next project

 

 

 

Here is helpful guide:

Typical Residential

3-5 tonnes

Small-Med Residential & Commercial: 10 – 50 tonnes

Large Residential & Commercial: 100+ tonnes

Green Case Study

West Australia Museum

The decision to specify anodising on this project has lessened the impact of our environment, as shown in the following audit

TONNEAGE of Anodised Aluminium used on project

Exterior Facades/Metalwork

Interior Facades/Metalwork

Glazing

Roofing

 

 

TOTAL (approx)

115 Tonnes

29 Tonnes

23 Tonnes

12 Tonnes

 

179 Tonnes

Comparison of Environmental Impact

The following table demonstrates the savings to the environment over a 100 year period.
Green House Gasses produced Energy Consumed
Aluminium Finish Weight of Aluminium Used - Tonne Co2 per tonne of AL Totals tonnes of Co2 kWh per tonnes of Al Total KWh
Exterior Smart 179 6.42 1.149 10.338 1,850,502
Powder Coating 179 10.36 1,854 21,493 3,847,247
SAVINGS by specifying Anodising 3.94 705 tonnes 11,155 1,996,745 kWh

Coverage and Protection

What is Edge Pull?

Powder and paints are primarily applied through spray systems. A coating applied to a sharp edge will pull back from the edge, leaving the edge with a lower film build. This is known as ·edge pull and creates weak points which are more susceptible to edge corrosion.

How Does Anodising solve this problem?

The Anodising process overcomes thIs issue in two ways. Firstly, the etching process is comparatively much more vigorous so has the effect of smoothing sharp edges. Secondly, the anodonic film then evenly grows the protective oxide layer around all surfaces, including edges and avoiding weak points around sharp edges.

Why is it important?

The Anodising process provides a significant advantage ln the durability of finishing any aluminium with sharper edges from perforations, punching, louvres, screens or any aluminium extrusions generally. Anodising has the winning edge cover that avoids the weak points that arise on paint /powder coating finishes.

Anodising Your Next Project

Project Feasibility

Specify with confidence at the design and documentation stage, Anodisers WA can offer architects a Project Feasibility Commitment (PFC). 

Anodisers WA PFC allows architects to know:

  • What is the most it will cost
  • Guarantee lead time
  • Quality Assurance Scope of work

Click here for an example of a PFC document

Design Factors In General

Anodising Powdercoating
Thickness 10-25UM 60-150UM
Hardness Harder than steel, PVDF, Sapphire Soft as Lead
Appearance Translucent Not Translucent
Coating Characteristics Cannot Crack, Peel and Chip Can Crack, Peel and Chip
Wear Resistance Excellent Good
UV No Affect Colour Can Fade

Architectural metalwork design

The anodising process consists of immersion of the metal parts Into acid baths and so the size of the bath limits the overall size of the metalwork to be processed. Also, the shape of the metalwork may have to be considered In order to maximise the space In the bath, and thus reduce the cost. This may have Impact on the overall design, so speak to AWA if you have concerns.

Aluminium to be anodised

Typically, aluminium ls anodised and Is in the form of extrusion or sheet the specification for each shown below is the desired alloy for either form. For specifications outside this range eg special alloys used for forming or casting, consult AWA as It may require sample testing.

Recommended sheet alloys

5005 H14

(Preferred material to maintain highest colour conistency)

5005 H34

(Secondary option if colour consistency is not critical)

Aluminium to be sourced from the same batch

 

Recommended extrusion alloys

6060 T5

6063 T5

Recommended suppliers

Capral – Local Supplier CA55 (5005 H14)

Novells J57 – Europe

 

Avoid using

Sheets wider than 1500mm

Sheets – alloy 5082 and 5083

Sheets – procured from multiple sources

Bath size limitations

Length 7000mm

Depth 1650mm

Width 500mm

Colour Process

AWA’s anodising is an electrolytic passivation process used to increase (grow) the thickness of the natural oxide layer on the surface of metal parts. Sulphuric acid is used to create a porous surface which can accept metal (tin) deposits which are very lightfast. For less light sensitive applications eg interiors a wider range of colours can be created using dyes, speak to AWA for more information. The anodised surface is then sealed after dyeing to increase corrosion resistance and dye retention.

Fabrication Processes - Welding

If welding is required for the design. it is important to use the most suitable method. TIG welding is generally considered to be more suitable than MIG. because it involves pre-heating which minimizes structural changes in the aluminium. which would result in colour differences. For best results use 5356 welding rods. If colour matching is required it may be best to perform a test run first. before bulk production. 

Racking

Parts to be anodised need to be racked/clamped during the electrolytlcal anodising process and therefore an allowance for marks which occur need to be taken into account. 

  • Extrusion are racked up to 50mm from each end.
  • Sheets are generally held in each corner up to 30mm with a leg mark on either side of sheets. For large sheets in excess of 3.6 metres long. additional leg marks maybe required in the middle of the sheet.
  • Custom folded, expanded or perforated parts please discuss with AWA.
  • Small parts are wired or clamped to aluminium racks. Where these racks or wires contact the part. There will be slight marks or ·contact points· left on the surface of edges of the parts.

Extrusions

Aluminium alloy in the form of extrusion for architectural metalwork application is typically in the 6060 or 6063 range with tempers of T5. For alloys outside of this range contact AWA.

Sheet

Aluminium alloy in the form of sheet or plate for architectural metalwork application is typically in the 5005 range with hardness of Hl4 or H34. 

 

NOTE: AWA has a preference for 5005 H 14 to avoid colour variances. For alloys outside of this range contact AWA. 

Colour Testing

Anodlsers WA uses sophisticated optical measuring equipment to test for variances based on the Delta E scale which Is a metric for understanding how the human eye perceives colour difference. 

Quality Management

AWA ANO-SPEC:

Working with Architects, Builders and Contractors to achieve the best possible outcome, project by project. AWA ANO SPEC 

addresses industry’s need to minimise variations arising from poor metal procurement. 

Industry Partnership

We have partnered with aluminium suppliers who also realise the importance of supplying correct metal for the specific anodising application. The benefit of working at all stages with the architects/design teams through to builders and contractors see projects maximise their full potential often with cost savings.

Flammability and Anodising - Aluminium cladding

Aluminium, especially in the form of composite, has been used for cladding high rise residential and commercial buildings for many years, however, since the Grenfell Tower fire tragedy, in the UK, and subsequent disasters in Australia where it has been proved that the facade was responsible for the propagation of fire, this material has become the subject of strict scrutiny. It should be noted that Aluminium Composite (ACP) Is not the same as solid aluminium. ACP includes an inner membrane of mineral or polyethylene material which affects the flammability. According to British Standard BS 476, solid aluminium Is described as non-combustible.

Effects of Anodising on flammability

Unlike other metal finishing, such as powder coating, the film Introduced by anodising aluminium Is etched Into the material not a deposit of dissimillar plastic material. However, as anodisers, we are obviously concerned about the effect of the anodising process 

and Its possible effect on the flammability when aluminium Is used for this application. To that end we have Instigated scientific tests to determine If the anodic film changes the combustibility properties of aluminium In any way. 

Laboratory of flammability testing

Flame ignition and propagation tests were carried out to assess the ignitability and flame propagation characteristics of anodised aluminium. In all cases the aluminium was not capable of being Ignited and it did not sustain a flame nor allow a propagation of flame. The testing showed that the anodised aluminium will not contribute to the propagation of a building fire as It will not ignite or burn unassisted. 

 

Delivery Guarantee

AWA is local and gaurantees that no client will wait longer than 12 days max for their work, regardless of the size of the order. Since 2018 AWA’s average lead time has been 9 days. We pride ourselves on transparent communications by publishing weekly lead time updates to over 350 Architects, Builders and Contractors.

 

Download Delivery Performance Audit Here

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