Surface finish after Anodize

[wchowe]

Hi All,
I am designing equipment that must seal an internal vacuum down to 80 Torr. I have seen a 32uin micro finish specified on similar designs for O-ring seats. I am concerned that a part with such a finish (on aluminum)will become worse once a clear anodize is put on the part as a final step.
Does anyone have any data as to what happens to the surface finish and why? What can I expect?
Thanks,
Bill

 

[TVP]

Metalast has an excellent website with a huge amount of technical information about anodizing. The following link has surface roughness data:

http://www.metalast.com/technology/pdf/surface_smooth.pdf