Anodising does not hide any marks, so any mark present on the surface of the metal prior to anodising will show through at the end. The quality of the surface finish prior to anodising will depend on your requirements for the final look of the product.
Die lines
Die lines are a result of the manufacturing process to make extruded aluminium lenghts. The degree to which these show up in the raw product varies depending on the manufacturing conditions at the time. Caustic etching will reduce the impact of die lines but will not entirely remove them, so die lines will remain visible after the anodising process.
Machining marks
A lot of the work now being anodised are CNC machined parts. Any machining marks present prior to anodising will show through at the end, this is not always a negative as certain machining swirls and the like, give a really nice look.
Bead Blasting
Bead blasting is a great way of giving parts a uniform finish. With regards to anodising you will need to note, that to get a nice anodised finish the parts will require a longer etch time and that this may impact on any tolerances and secondly that the parts will be fairly matte in appearance.
Where possible Advanced Anodising Ltd will notify customers customers if they have concerns that the final anodised look may not be what the customer is after as a result of the surface preparation. Advanced Anodising Ltd takes no responsibility for any quality issues that relate to the preparation of the parts prior to anodising. Advanced Anodising will assume that customers are aware of the quality of the surfaces on the parts and can not be held responsible if this does not actually meet their requirements.