The phenomenon of cable-shaped indents in the plastic cases of retro systems is one that’s probably painfully familiar to many a collector of such systems. Although in these situations neither side got hot enough to cause any melting – especially while disconnected in storage – it still has that same melted appearance. The real cause here is not heat, but plasticizer migration, as detailed in a recent video by [Run Stop Restored] over on YouTube.
Plasticizers are an additive to many plastics that aim to make it more flexible (‘plastic’), as well as improve other characteristics of the base material, with PVC in particular relying on plasticizers to give it its desired properties for applications where PVC has to be flexible. Here the flexible cable insulation of these devices generally uses PVC, which over time can migrate to other polymers when brought into close contact for extended periods of time.
The – usually ABS – enclosures of e.g. Commodore tape drives as in this video demonstration thus get correspondingly inundated with the same type of plasticizers that ABS is also highly susceptible to. Since in storage the cables tend to be wrapped – tightly – around the device they’re attached to, this results in a solid contact which thus enables this gradual process to work its magic, whether it’s a Commodore datasette or a power supply brick.
Correspondingly the PVC insulation becomes brittle as it loses its plasticizer, with the process sped up by higher environmental temperatures. To prevent this, never wrap a PVC cable around a device, and keep it physically separated from susceptible plastics like ABS as much as reasonably possible. Along with a cool environment this should prevent plasticizer migration from ruining what used to be a pristine case.
This problem is particularly significant for retro gear from the 1980s and thereabouts, before phthalate-free plasticizer alternatives were developed, along with other changes such as more stable formulations that prevent this migration process. Adding a coating can also help, especially for protecting older gear, but flexible PVC in particular should be viewed with suspicion and treated carefully.
Noticed something similar with those cheap cables. It’s not so much brittle, but it feels different.
Does it help to clean sticky old cables using IPA?
You know, I’d seen this in action and just assumed at some point I left a hot soldering iron on, but this makes sense.
The 2020s equivalent is tech that has that soft, almost rubbery exterior. These tend to melt in humidity to turn into a sticky mess after a few years. In Florida I have so many old cameras and the like that are now fuzzy, because the exterior became an adhesive over time and dust or mold sorta “grew” onto the exterior… it’s so gross.
Even if the device still works, it’s e-waste unless you are willing to cover it with masking tape to make handling it tolerable. I’ve tried goo-be-gone and it never quite gets it all, because it’s like the housing is MADE of glue at this point. Device housing manufacturers need to be more cautious. I’d rather go back to beige yellow aging housings than deal with this sticky mess.
This was very enlightening. Years ago, I discovered that some ordinary insulated hookup wire had “melted” the plastic box it was in. I think the box was polystyrene, but I’m not sure. I never understood what had caused it.
Leaking plasticizers are a known problem for more than half a century, they can damage most plastics even without direct contact. Also rubber parts will absorb the fumes and turn into goo after a short time. Many nice things were ruined just by storing them in an airtight bag or box.
Oh, so THIS is the underlying reason why soft-body lures left contacting a hard plastic bobber seem to melt into the bobber when left in a tackle box for a couple years.
Huh. Noted.
Yeah! You’re right!! I really thought that was heat because the tackle box always got left in the barn. …… world model updated.
I had a related version of this phenomenon in an older house I was living in. Green goo would seep out of the light switches in certain rooms. I later learned it’s the plasticizer migrating along a cable’s outer and inner insulation layers. Then it would flow through the light switch, picking up a little bit of copper/brass along the way from the switch mechanism.
Also mention cords on wood finishes like the top of a piano, or placing the vinyl bench on top of the lid.
When you wrap cords you might as well chuck the end in a drill and give it a whirl, it’s twisted.
materials incompatibility, this is why i keep my dildos separated. for a friend.
Your friend doesn’t like their dildos to touch either? What’s up with friends, amiright?
Another annoyance (though smaller than a melted gap in your priceless retro possession) is the same effect on its polystyrene packaging: Cables can melt large gaps into styrofoam because of its “air’y” nature. Melted styrofoam basically fuses with the cable, so that cleaning the cable becomes tedious.
I guess putting cables in polyethylene bags helps, or at least wrapping them in paper.