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What causes paint bubbles / micro blisters in my die-cast metal model car (READ AHEAD IMPT DETAILS)?

• What causes paint bubbles / micro blisters in my die-cast metal model car (READ AHEAD IMPT DETAILS) What causes paint bubbles / micro blisters in my die-cast metal car? Below are details of the model car history and "life-span". Since this model car is made of metal, let us assume that this situation can be applied to any "painted metal surface". i purchased this model car about 2 years ago. On its first year, the model car (again die-cast metal built) appear elegantly and has the smoothest paint finish it ever had right from the box. having owned this pristine beauty, it was displayed on an area of the house that had slight accumulation of dust. The only thing that i was bothered about is that, that former place i had, being in a tropical country, ambient air was very humid - whole year round. Another year later, i migrated here in the US. Currently in the Northern end of the United States, its cold, and the ambient air is mostly low on humidity, and of course very very much dust free. But since the place was cold, the house was cold - - we had our heaters ON most of the time. But before i had my model car displayed here, in my new place; originally, the model car was kept on our clothes closet, where, i assume was cold and slightly moist along with its cardboard box... it was there for about 3 months. Now, i had this model car displayed outside, and is current on the heated area of the house. I was wondering though, few weeks after the model car was displayed, some areas of the car have paint bubbles... its actually micro-blistered, and doesn't really look nice... Is it possible that the change in temperature and ambient air humidity could have caused this? I do hope i can receive some answers... it really is a wonder since, its been a year and it never had these bubbles, considering the model car originally came from a very hot-humid-country. But how come, that i am now here on a dry-properly condition-temperatured room, all these micro-blisters came out? Or is it really a simple story of aging? Thank You Very Much to All Correspondents!

• Answer:

  What I'm guessing (after 30+ years of painting models: plastic, wood, and metal) is: The original paint job was done on a not-quite-clean metal surface !! The slightest bit of wax, oil or dust prevented the proper paint adhesion on the spots that are giving you "micro-bubbles"... I'm GUESSING that while living in that warm and humid area, the temperature and humidity RANGE was minimal, so you didn't notice any imperfections becaus the paint didn't "flex". THEN in your journey to the Northern US, the model attracted some moisture, AND in the coldness of the closet the paint contracted. NOW in the conditioned air of your new house, the moisture has migrated to the dust or wax or oil points UNDER the paint. The moisture has lifted the paint. Not sure of the CURE... other than placing in a sealed box with silica dehumidifying packets... GOOD LUCK