Anodizing aluminium reduces fatigue strength. what about climbing hook? 1

[tronics21]

Hi,
While I was researching about anodizing aluminum I learned that anodizing aluminum reduces fatigue strength of the material.
So that aluminum parts can fail and break under the load below their endurance limit.
I realize that most climbing hooks on the markets are anodized and dyed.
Why do they anodize climbing hooks? This doesn't make sense to me because they are very safety critical!
Maybe I am misunderstanding something here but this made me really puzzled.
Any thought? comment?

Thanks,

 

[johnSchwaner]

their more pretty when colored

Protection from corrosion, which also reduces fatigue strength -- as long as there are no scratches through the anodizing!

 

[Screwman1]

When you say climbing hook, I'm guessing that you mean a carabiner, right? These are not intended as fatigue items, they are virtually unloaded until a fall, in which case they see a high tensile load of one or two cycles duration. It isn't a fatigue environment. If it is used at a commercial climbing gym as a top anchor they use a screw closure SS loop, not a carabiner. The only time you would get a fatigue load would be during a rappel. I've never seen a carabiner that failed in fatigue- every single one has been a tensile failure or a wedge loading.