Sinclair ZX80 Case Maintenance

[n6il]

I have a North American ZX80 which I got at a flea market a while back. When I got was in fair condition, the case was not broken. I took it off the shelf today and it is still electrically functional. But now after sitting a few years the case is starting to yellow and I have noticed that cracks have developed radiating out from the holes where the plastic rivets are installed. With those cracks I am now worried about storing the machine with those rivets installed. Can anyone make any recommendations on what else I can do about this situation? Could I for example use dab of CA glue to try to keep the case cracks from expanding further?

 

[tejones777]

I know exactly what you mean. Plastics from the 60's and 70's degrade really bad. I have two ZX80's which are quite yellowed, and fragile.

Almost all whitish plastics from the 1970's and 80's would turn yellow and crack very fast. Almost as if it's drying out. I used to scrub yellowed calculators in the 70's and 80's to turn them white again, but the thin case of the ZX80 won't allow a lot of scrubbing.

Most important: Avoid light. Especially sunlight, but even fluorescent lights will be a problem. Sorry. Takes away from the joy of displaying your stuff.

Modern museum conservators have been looking into this, and there's some information at the Getty Museum's Getty Conservation Institute web pages here....

Preservation of Plastics

Long-term project to study wide range of plastics to understand how to prevent or slow down their degradation.

www.getty.edu

Even modern plastics tend to yellow and degrade, but many have additives to block UV light and help that. Even plexiglass or polycarbonate windows used in homes will degrade in the sun, so they always have to have a special coating to block the UV light. I've seen new items made on 3d printers, when white, yellow with only 10 minutes in the sunlight, so some people spray paint their 3d print models3d resin printers so they can stand the outdoors a bit better.

I'm not sure if you want to try this, but if you look here...

this fellow on YouTube is using a product called "Salon Care 40" which turns the yellowed plastic white again, "with the help of UV light" which seems counter-intuitive. But after it's done, he still uses a UV blocking film to prevent future yellowing. I would not recommend this mystery "Salon Care 40" on a Sinclair ZX80 case, as the case is so thin, I worry it will worsen the brittling and cracking, but it's interesting.

There's a lot of information on the internet with using "magic eraser" or "lemon juice" or "a paste of baking soda" but since collectors of vintage computers don't just care about the white color, we also want the plastic to last forever, I doubt any of these things would be considered "museum safe."

- Thomas.

 

[tejones777]

I read a little more about the "Salon Care 40" and as the name says, it's a strong chemical used in professional hair coloring. While it magically does seem to whiten yellowed plastic, I really worry it will long-term degrade the plastic, and make it even more brittle and crack-prone. Please don't use this.

Hopefully someone else will know more. Something that maybe museums are using. A coating that blocks the UV, and also preserves the underlying plastic.

- tj.

 

[NeXT]

Sounds like another take on peroxide-based whitening. ("Retr0brite") The process is known to weaken plastics and until a better chemical process is found it's generally recommended from a preservationists perspective to leave it alone, especially on plastics that have yellowed from bromide yellowing as it will eventually yellow again.