On Christmas Day 1986 I ripped the wrapping paper off the only present I remember from that year. I found myself staring into the eyes of a dinosaur, but not just any dinosaur, a grey and gold mechanical monster named Grimlock. He was the second Transformer figure I ever received, and a figure who received much love, but alas like all things Grimlock aged, and in the world of plastic toys that meant the dreaded yellowing, a brittleness and discoloration of his plastic that eventually led to his demise (well that and leaping from a second story window, I saw him fly in the show damnit).
So what causes this yellowing, why do the plastics that make up your favorite childhood toys and collectible figures become discolored and brittle over time, and most importantly how can you stop it? Well realistically you can’t; you can only slow it down. However to do so you need understand a bit of the chemistry of plastics. How they are made and what they are made of. I’m by no means an expert, but I’ll try to lay out the basics here.
Plastics are a type of polymer, a polymer is a large molecule made up of thousands and thousands of smaller molecules called monomers. Mix in additives like UV absorbers and plasticizers and you have yourself a basic plastic. Different mixes give you different results, from rigid but brittle clear plastics to the softer rubbery plastics often used for weapons and pointed objects in modern toys. All of them age at different rates but the techniques for caring for them are basically the same.
Over time the bonds in a polymer in any particular plastic will begin to break down, as this happens they release free radicals. These are atoms that cause a chain reaction that speeds the aging process. In plastics they cause the yellowing, as well as blistering, brittleness, and pretty much all the other nasty things seen happening to old toys. Heat and UV radiation accelerate this process. Thus the reason most plastics have some amount of UV absorbers in the mix to absorb the incoming UV radiation and the free radicals. Of course you have a limited amount of UV absorber in any mix and once it’s all used up the plastic is going to start aging very quickly.
Plasticizers are another big part of a plastics composition. If you’ve ever gotten into a new car and smelled that unique scent, that’s from the plasticizers; and if you’ve ever gotten into an old car and seen a dashboard that looks like its been in a meat grinder you’ve got an idea of what happens once its all leached out. Plasticizers are basically compounds that give the plastic flexibility and allow it to have a bit more bend before breaking. Over time heat and UV radiation cause these compounds to leach out and causes the plastic becomes brittle.
Obviously the easiest first step is to keep your toys and collectibles out of direct sunlight. This prevents the bulk of the UV radiation from reaching them. The second step is keeping the room or case they are in at a constant cool temperature. Somewhere in the around seventy-five degrees Fahrenheit is probably optimal. Not quite as important for the plastics themselves but for the other parts of a toys be it metal or the stickers and paint is to limit the humidity where the toys are stored. This prevents paint and stickers from peeling and metal from rusting.
Understandably we don’t all have access to climate controlled display cases, but as long as you can keep at least one small room shaded and reasonably cool you should be fine. Hopefully this helped some of those who are trying to figure out how to care for your cherished toys, and explained for others why the hell those childhood treasures you pulled out of the attic looked like hell. Happy collecting boys and girls.