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.