When Half of a Game/System Turns Yellow
Over the course of my time as a collector, I've often seen old carts (and consoles) with UV damage and yellowing. With a little help from Google, I've vaguely figured out that this appears to be the result of a fire-resistant chemical used in the plastic compound the carts are made from, and this compound causes the normally grey plastics of the carts to turn a tinge of yellow after prolonged exposure to ultraviolet rays. From what I've read, this compromises the molecular structure of the plastic, and that the yellow staining isn't just on the surface, but rather saturated throughout the plastic. I've seen all sorts of videos on youtube of people trying to use peroxide concoctions and UV lamps to try to reverse this yellowing, and it looks like a real pain in the ass.
Anyways what I'm getting at is, why does this only happen to half of the plastic of a cart or console sometimes? I used to believe that someone must have just simply switched backs at some point in the game's life cycle, and the replacement backs sometimes don't match the original fronts due to UV exposure (yellowing). But then I realized that a few of my old childhood NES carts have this staining on just half of the cart, and they are all certainly completely original copies. I just received a copy of Mario Party 2 NFR (with back sticker so it's highly probable the 2 halves go together), and the back half of the game is so yellow. The front half is bright grey and looks near new, and then the back half is so yellow it makes the cart look like a copy of Pokemon Stadium 2.
So, why does this happen? The only thing I can guess is that once a piece of plastic is "infected" with UV damage to its molecular structure, that the UV damage must spread throughout the rest of the piece of plastic over time. Since game carts are comprised of 2 separate halves, I've always figured that maybe one half was affected by the UV damage, and the other wasn't since the damage cannot spread beyond the seam that separates the 2 halves of the cart. The difference between the 2 halves of this cart is enough that it seems the front side would have to be affected by what it appears the back side has been through.
Anybody have an accurate explanation of why this happens, or who can confirm or deny my assumptions up to this point?
Anyways what I'm getting at is, why does this only happen to half of the plastic of a cart or console sometimes? I used to believe that someone must have just simply switched backs at some point in the game's life cycle, and the replacement backs sometimes don't match the original fronts due to UV exposure (yellowing). But then I realized that a few of my old childhood NES carts have this staining on just half of the cart, and they are all certainly completely original copies. I just received a copy of Mario Party 2 NFR (with back sticker so it's highly probable the 2 halves go together), and the back half of the game is so yellow. The front half is bright grey and looks near new, and then the back half is so yellow it makes the cart look like a copy of Pokemon Stadium 2.
So, why does this happen? The only thing I can guess is that once a piece of plastic is "infected" with UV damage to its molecular structure, that the UV damage must spread throughout the rest of the piece of plastic over time. Since game carts are comprised of 2 separate halves, I've always figured that maybe one half was affected by the UV damage, and the other wasn't since the damage cannot spread beyond the seam that separates the 2 halves of the cart. The difference between the 2 halves of this cart is enough that it seems the front side would have to be affected by what it appears the back side has been through.
Anybody have an accurate explanation of why this happens, or who can confirm or deny my assumptions up to this point?
Comments
I remember seeing SNES consoles with yellow parts and gray parts even years before the N64, so it didn't take long for the problem to become visible. I'm pretty sure it prompted the creation of new quality control measures, which is why later units and the 101 model didn't seem to suffer from it.
Anybody have an accurate explanation of why this happens, or who can confirm or deny my assumptions up to this point?
CZroe's post about the flame retardant compounds is almost certainly the correct answer.
As I understood it, this is also why so many light switch and outlet cover plates from that time period (and still to this day) come PRE-yellowed (so they don't later change color due to UV exposure).
Rat piss
This exactly
Rat piss
This exactly
Lol
I lew it! Never could catch o r in the act. Look at that lil fucker rat pissing all over the back of that SNES cart. Fucked it up too. Smh.
The parts aren't all molded together. They'll make a batch of controller blocks, a batch of bottom shells, a batch of top shells, a batch of nameplates, etc in whatever sequence they need them. The plastic supply is replenished as needed and the BFR levels are invisible before they oxidize, so some batches will get made with a completely different mix from others. My guess is that uneven mixing of BFRs in the source plastic is to blame. I'm guessing that the BFRs act like a catalyst. Some batches cross a threshold where there is enough of the catalyst that runaway yellowing happens, others stay well below.
I remember seeing SNES consoles with yellow parts and gray parts even years before the N64, so it didn't take long for the problem to become visible. I'm pretty sure it prompted the creation of new quality control measures, which is why later units and the 101 model didn't seem to suffer from it.
I'm pretty sure this is the answer!
I constantly see yellowed SNES systems. Always assumed it came from being in a home with smokers.
Retrobright wouldn't work it's magic on them if that was the case.
Anybody have an accurate explanation of why this happens, or who can confirm or deny my assumptions up to this point?
CZroe's post about the flame retardant compounds is almost certainly the correct answer.
As I understood it, this is also why so many light switch and outlet cover plates from that time period (and still to this day) come PRE-yellowed (so they don't later change color due to UV exposure).
We call those "almond" colored LOL reminds me of the 80s