Could someone please give me some info around the 'performance difference' of powder coated windows vs anodised. Am keen to understand scratch resistance/durability/sun fade/pitting resistance...


Also, does anyone know what 'Anotec' means with regards to Dulux powder coating colours? Can't find anything anywhere. Would just be intested to know if certain colours in the range perform differently...

thanks for any help you can provide,

Lachlan

lachlan,

I'm not an expert, but have chosen anodised aluminium for my windows for my upcoming build.

The reason I chose anodised aluminium is that it lasts forever. There's nothing to breakdown and if you left an anodized piece of aluminium for 100 years, came back and gave it a clean it would be as good as new (I think). Powder coating will eventually decompose and need to be replaced.

Anodised aluminum is probably not too scratch resistant, but once your windows are up, they rarely get scratched. However, during building you have to be careful not to scratch the surface and not to get mortar on them (since it stains the anodised aluminium).

From what I can gather colours like Dulux Anotec and Anodic are just powder coat finishes that mimic the colour of anodised aluminium (anotec, anodic and anodised all sound the same and refer to the anodising process in which the aluminium is the anode (the positive terminal) in the plating process.

Once warning however, I wouldn't use anodiesd aluminium near sea water or within a kilometer of seawater. The salt eats away at the aluminium.

Cheers,
Casa

Hi Casa2,

You said not to use anodised windows near sea water as the salt affects the window...What about a lake? Do you think this would be a problem?

Anodised has been popular, less so now - it can corrode near sea water. In Australia it is dearer than powdercoat but elsewhere it is cheaper. If it gets damaged you cannot repair it. Mortar permanently stains it.

Although we can supply anodised, we use only powdercoat as it can be repaired (scratches dents etc.) - you should see no detrioration in powdercoating under normal use in 10 years - and I have never seen any deterioration other than mild colour fade and loss of gloss - both of which are minimised if the windows are cleaned regularly. There is no paint subsitute for anodising in a paint process.

The most durable finish process is 2 pack wet coat which will endure longer than both, nobody supplies this in windows to my knowledge. The depth of anodising is critical for product life.

Sea water is a problem, but a lake should be OK (if it's freshwater). The problem isn't the water but the salt (sodium chloride). Anodising is aluminium oxide, which does not dissolve in water and therefore offers protection. Aluminium chloride on the other hand dissolves in water.

I've heard that when close to sea water the anodising has to be increased from 20 um to 25 um thickness, but I'm not sure how such a small difference in oxide layer can offer such protection.

Standard clear annodised is 15um. I have used 25um in the past in sea side areas with no problems. Whatever you do, don't get black annodised, any water will stain it.

Both types of windows scratch. Except with powder coated you can paint over it with touch spray can and you will never no it was scratched. You can not do the same with anodised. This is important during construction have a good chance of scratching windows when stacking/moving them etc.

Would rather have a few scratches on anodised aluminium than painted. Persoanl preference.

Get your supplier to tape up the exposed aluminium to prevent damage by handling and during construction.

thanks for the advice Eco.

Powder coating may result in a much more efficient production process for the window manufacturer. They can easily incorporate the process in-house and dont have to keep stocks of different anodised aluminum colours. Just in time manufacturing.

Also with powder coating the manufacturer can repair any product scratched during the production process - so it leads to lower product loss.

Greater efficiency = lower costs.

We ordered an anodised door (to match older anodised windows) on a commercial site. The cost was higher and the manufacturing time was much longer as they did not stock the anodised aluminum.

We just went through this issue - powder coat v anodised.

Anodised was almost 10% more expensive than power coated.

The design required silver/grey windows. We had them send out a sample of powdercoat (anodised look) and anodised.

We found the powdercoat was more scratch resistant than the anodised sample.

So initially we decided to go with powdercoat on the basis of cost. We then went to check it out in place on another home. I was surprised by the look of the powdercoat - it looked ok from 20m but as you closed in it just looked more and more like a cheap imitation of anodised.

If it was windows only then we may have been able to get away with powdercoated (though this does not change the fact that it would have been a price driven compromise). But there is also a feature bi-fold external door in the design and it was obvious that doing it in powdercoat would have been a mistake.

So we ended up paying the extra for anodised.

Good to hear you went for anodised. I would have thought that anodised aluminium is more scratch resistant than painted, for reasonably hard scratching. Anodising is supposed to be 90% the hardness of diamond. However, it've very thin (0.02 mm) and the aluminium beneath it is soft, so if enough force is applied then the anodising will collapse and the soft aluminium will scratch.

I'm let to believe that once the build is over, with normal usage, the chance of a scratch is low. Also the finish (unless you are near salt water) will last forever.

In true cost terms, in a free market, powdercoating is an expensive imitation of anodised. It is only the way anodising is charged in Australia that makes it more expensive. Take care, it is permanently marked by mortar.

Ed

Surely someone has devised a way for anodised aluminium to have mortar marks removed.

About the best thing you can do it try and clean it with an aluminium rubbing block. But as with anything, prevention is better than cure, mask them with protective film before they are installed.

very informative post. thanx guys

We have a waterfront property and have been advised to have anodised windows - is that the wrong advice?

If it's coastal I would say yes, wrong advice, unless you are going to pay for extra thick anodising. Personally (and 50,000 houselots later) I have not seen any significant deterioration in powdercoating in coastal areas, but it is often quoted as a problem.
Ed

We are in Sydney and the property faces a bay, not the harbour. Both the builder and the architect thinks this is a better way to go compared to powder coated. I was a bit concerned after reading this thread.