I order a metal 3d print on February. To be precise a Polished Bronzed-Silver Steel print. I noticed the color has changed a little over this time period, it is becoming a bit yellow-ish, I suppose one of the metals is oxidizing. I am a noob, so I wonder, does this kind of print needs a coat? It is a hook for a spring mechanism, so even if I apply some type of coating it will wear and scratch on the contact places. Can I leave it as it is now (uncoated)? Does oxide change the durability of this print in a significant way?