Almost any finish that can be applied to a Steel Alloy mold can be applied to an Aluminum mold. This includes finishes and surface grades from SPI, Mold-Tech, Raytheon or any other industry, OEM finish specification. It’s very rare to find a finish that cannot be applied to Aluminum. This myth may come from small closed in features on a design where it’s difficult to apply texture. Or the extra hand work required in polishing highly aesthetic surfaces like those for optical components, chrome plated
, or any other texture finish that requires an ultra smooth finish which is touched and seen by the consumer that might be more work than some rapid tooling shops specialize in.