Not concerning radios as such, but further to the discussion on restoring plastic cases, I have come into possession of a pair of vintage toy telephones made in Japan and dating to the late 1950's or early 1960s. They have been stored in their original box for probably 50 years.

When I opened the box I was greeted by something that I've never seen before: one form of plastic attacking another.

While stored in the box, the curly cords that connect the receivers to their handsets have been in close contact with the plastic cases of the handsets.

As you can clearly see in the photos, the curly cords have dissolved the cases and left them deeply scalloped in the shape of the cords. It's just like a soldering iron has melted the plastic.

Googling around I found some references to the plasticisers used in some cable insulation, over time, attacking other types of plastic, particularly polystyrene. I'm guessing that the plastic used by the Japanese back in the day was a form of, or a relative of, polystyrene.

Has anybody has come across this problem in relation to plastic radio cabinets/cases?

At first I thought, this couldn't be right but there it is in living colour.

If the case of the telephone is made of a styrene-based plastic then that will do it. Polystyrene is not only unstable compared to other plastics but is also brittle and highly susceptible to damage by chemicals such as acetone and perhaps even the chlorine content of the PVC sheathing of the cord.

I remember when black jiffy boxes [for Jaycar (Bill Edge Electronics), Dick Smith and Tandy kits] came out, they used to break like potato crisps. Later versions of these boxes were made of stronger, more flexible and more chemically stable plastics.

I've seen this happen before but not as bad as this. I try not to store any equipment with PVC cables pressed against plastic surfaces to avoid this occurring.

PVC is not a particularly stable plastic and sheds plasticisers as it ages giving the plastic an oily sticky surface. The plasticisers make good solvents as well judging by the ease with which the cables mould themselves into any plastic surface they are pressed into.

I asked about any instances of this problem affecting radio cases and, lo and behold, a crystal set popped up on eBay with a dose of this problem, caused by the earphone cable being wrapped around it.

Granted, the crystal set's plastic case (presumably made in Japan) is probably made from a similar plastic to the toy phones, but it is a radio after all

I've seen this happen with late 50's early 60's AA5 radios. People often wrap the power cord around the plastic cabinet. Leaving the damaged cabinet plastic where it sat.

As annoying as batteries that leak. Why do battery manufacturers insist on putting corrosive carp in batteries anyway. A conspiracy with flashlight manufacturers?

Once had a 14" General TV which was in storage and had a similar problem from the cord getting underneath.

I have had this happen to a little Westinghouse valve radio I bought from the USA. I complained to the seller about not telling me of the burn marks on top, now I realise what had caused it. He thought it was a pattern and supposed to be there,
Peter

There was and article related to conservation of plastic items, in one of the bigger scientific publications. I may still have a saved copy?

Plastic was considered the indestructible wonder material of the twentieth century....... so wrong. Some loses its plasticiser & becomes brittle with heat... lots of 50's radio cabinets. Bakelite & Catlin seem to be a bit more resilient.

The stuff "Barbie" dolls & such are made of is decomposing, one of the decompositin products is Hydrochloric (muratic) Acid aka "Spirits of salts". This is a chain splitter for "Acrylic" and an catalyst / accelerant for further decomposition.

Its a bit like Nitrocellulose, as used in early films and as a furniture finish. It can self sustain its own decomposition in a variety of situations.

Marc