Distinguish bare from finished stock
Aluminum may arrive machined, brushed, blasted or with a coating already applied. Those descriptions are not interchangeable. Include the alloy and delivered surface condition in the inquiry. If the drawing uses a general material description, confirm the actual production material with purchasing or engineering before requesting a trial.
Choose the mark location deliberately
A convenient open area is not always the right place for a permanent identifier. Consider later machining, installation and inspection access. For a housing, show which face remains visible after assembly. For a small part, identify whether the mark must be readable before or after the part is fitted into a larger unit.
Keep future finishing in view
If anodizing, painting or another operation follows marking, include that step in sample evaluation. Ask who will inspect the final appearance and whether the required information remains visible. For recurring orders, retain the surface preparation and operation sequence with the approved artwork. A change in finish should be treated as a reason to review the marking result, even if the identifier itself stays the same.