We’ll start with the least damaging of the five. If left for long periods of time, dust may become hard to remove. Especially in climates or houses with extremes in humidity (dust will hold humidity). That process will make the dust adhere strongly to the figure and won’t wipe away easily with a duster. Additionally, figures just don’t look good covered in dust. Best practice? Keep your collection in closed cabinets.
Your hands are the next problem. Wash your hands before handling any figures. The oils from our skin make it easier for dust particles to accumulate and build up.
Most toys are made of plastic, or at least some plastic. Most plastics, if not all, will begin to change shape with heat (warping or bending). With vintage Transformers this is not much of a problem, but most collectors either have other action figures or newer Transformers which are more prone to this issue.
Now we generally don’t have to worry about our collectables getting wet do we? Okay so I’m not talking about them going swimming for a day. I’m talking more about long term exposure to high humidity. High humidity, especially along with a little bit of dust which will hold that moisture, will cause oxidation and even light rust. I have seen entire collections that are spotless, and even near mint where every figures screws have a light white film on them.
Keep your toys out of direct sunlight. Sunlight will cause the figures’ colors to fade/yellow/discolor or even become blotchy/spotty. The worst looking toys by far are these, and so many collectors are making this mistake. Even indirect sunlight, yes indirect sunlight will cause a problem over a long duration.
I’ll cover each of these in more depth in the future. And cover more specifically about sunlight, direct, indirect, fluorescent light (which also emits UV) and how UV coatings and materials don’t always work like you think!