UV Safe Anodized Aluminum

[R. A. Mitchell]

I've been re-reading threads about anodized aluminum. Seems like 3-5 years is about the best one can hope for with black anodized aluminum under outdoor conditions, and brighter colors fare much worse. Has anyone tried coating it with clear coat to prolong its outdoor durability? I have a customer who really likes the look of anodized tags, but he needs it to last at least 5-7 years.

Thanks!

[Mike Null]

I've used black anodized outdoors for as long as 8 years with little or no degradation. It is also the material of choice for hundreds of outdoor signs at the Missouri Botanical Garden.

[Bob Davis]

I've got the same question. I also have a local product called "Liquid Armour" which is used to clearcoat brass and other metals and is supposed to have great UV resistance.
I couldn't get a definitive answer about durability from the manufacturers
so I started a trial with coated and uncoated items left in the open. That was 6 months ago, so I'll be able to tell you more in about 6 years...
They both still look perfect at this stage.

[Rodne Gold]

Durability of Anodising depends on the dyes used and the sealing process after its dyed...
I have never had problems with anodising lasting if the anodising was done by reputable companys.
I also have anodised parts I did myself with a bucket of battery acid , a battery charger and food dyes , that are well over 10 yrs old , and that live in a hot engine bay , and they still look good.

[Dave Johnson29]

I've been re-reading threads about anodized aluminum. Seems like 3-5 years is about the best one can hope for with black anodized aluminum

Hi Robert,

Can't see it really. If it is 3-5 years it must be pretty poor anodizing processing. I have some parts on my motorcycle I had Type II anodized black along with a bunch of my production items back in 2001.

This bike is never covered or garaged and and I live in Northern AZ at almost 6000ft altitude so UV is pretty fierce here. Also Arizona has the highest number of sunshine days of all the States. The parts still look like the day I got them.

Maybe they are talking about Type I anodizing but I really can't see it with that either. I am with Rodney, poor processing if it is 3-5 years.

[R. A. Mitchell]

Thanks, guys. I looked through threads on this forum, and the 3-5 years was a but of an understatement. I was taking the lowest estimate I could find because I don't want to sell a product to someone overstating its durability.

I suppose a better way to look at this would be to compare the durability of anodized tags with die sub tags. Are they comparable? I have some literature from a major tag maker who indicates that die sub tags are "suitable for indoor or outdoor use up to 7 years." Does that sound about right? If so, that seems to put them on par with laser engraved anodized tags.

[Mike Null]

Under no circumstances would I advise customer that dye sub would last more than a year outdoors. The new inks are better but still not UV stable.

UV clear coating will not appreciably lengthen the life.

[Dave Johnson29]

I suppose a better way to look at this would be to compare the durability of anodized tags with die sub tags.

I don't do dye sub but the local awards and trophy guy (no laser) does and he told me 6 to 7 MONTHS for direct sunlight and the die sub is all gone to white.

For Type II black anodized I would guess ate 15 to 20 years.