Durability Requirements: The most important consideration is the operating environment where the item will be used. Requirements are typically expressed as the ability to withstand one or more of five conditions: sunlight, abrasion, heat, chemicals, and salt-spray corrosion.
Specification Requirements: Many industrial products are purchased based upon specifications. Specifications are either global (i.e. apply to many different companies) or company-specific. Global specs are often established by the government, military, or some other industry-wide organization. Company-specific specs are just that: specific to a single company. You can look up almost all global specifications on www.everyspec.com. Common specifications for graphic identification items are MIL-STD-15024F, Type L, and A-A-50271.
Appearance/Readability Requirements: Choose the material that creates the appearance best suited to each customer’s needs. That could be barcode readability (not all materials read well on barcode scanners) or contrast of black and metal surfaces.