Anodising Appearance Variation

[VoiceOfTheBook]

Hi folks,

I'll keep it brief: I'd be very grateful for an opinion from some of you learned chaps on the cause of the variation in appearance of the attached. This isn't something we've encountered before.

Both of the aluminium parts shown (there are two, call them top and bottom) were supplied as 5083 tooling plate. Both of those parts have been bead-blasted and anodised in the same batch. The bottom is from 1" plate and the top is from 1.1/4" plate.

I doubt that the difference in appearance is accountable to the minor variations between the 1" and 1.1/4" plates (assuming they are both 5083).

And I've not seen that much of a variation in similar materials that have been anodised in the same batch before.

Which leads me to suspect that one of those parts is not the grade it's supposed to be? Thanks in advance.

Edit: we have several units of both of those parts, all of which have been anodised in different batches and all exhibit the same variation, i.e. tops look different to bottoms.

Best regards.

 

[tbuelna]

The surface of the upper part looks like it may have been put in a vibratory tumbler before anodizing.