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AuthorTopic: Non-retr0bright de-yellowing.  (Read 3226 times)

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Offline danamania

Non-retr0bright de-yellowing.
« on: January 24, 2017, 12:10:15 PM »
Posting in here because I wasn't sure of the best place, not having been here for a long while.

I've used retr0bright a fair bit on my old Macs, and it does the job. Curiosity about the causes of and fixes of yellowing lead me to leave some plastics out in the sun for a bit, to see if I could induce yellowing (and how quickly it might come on).

Turned out a week and a bit in bright summer sun near completely de-yellows old Mac plastics. That was a surprise.

some pics below:




Manufacturer plastics vary of course, so what works on the typical Mac plastics may give a very different result on those used for Amiga cases, but thought I'd share the idea in case anyone wanted to give it a burl. I've only done a few pieces so far, and I've now packed them away with a reminder to check them every month to see if there's any re-yellowing or even extra-yellowing that's yet to show.

The top case in the pics above I just sat on top of a garden shed for 12 days total. I left it out overnight, and all day during midsummer sun and >30C temps (and a couple of thunderstorms). No other treatment than Lots Of Outside.

Dana
 

Offline paul1981

Re: Non-retr0bright de-yellowing.
« Reply #1 on: January 25, 2017, 07:31:49 PM »
Hello there. So you didn't treat the plastic except for blasting it with raw sun light? And this actually reduced yellowing? Sorry if I'm being dumb here (wouldn't be the first time), but that sounds like an April fool. :laughing:
 

Offline nicholas

Re: Non-retr0bright de-yellowing.
« Reply #2 on: January 26, 2017, 12:34:33 AM »
Sunshine? What is this thing you speak of?

Yours inquisitively from Manchester.
“Een rezhim-i eshghalgar-i Quds bayad az sahneh-i ruzgar mahv shaved.” - Imam Ayatollah Sayyed  Ruhollah Khomeini
 

Offline danamania

Re: Non-retr0bright de-yellowing.
« Reply #3 on: May 17, 2019, 05:43:29 AM »
Thought I best followup a couple of years later with my results. I didn't check my Q605 for long-term damage after sunbrighting until recently when some other forums picked up on the technique and I saw a lot of folk putting their machines out in straight sunlight. I dragged the 605 out, and it didn't end well for the poor Quadra.


 

guest21671

  • Guest
Re: Non-retr0bright de-yellowing.
« Reply #4 on: May 18, 2019, 03:47:23 AM »
No need to double post with the same overly large photos
I remember those.  The yellowed back in the day when they were in use and sold
Retrobright and Lightbrighting both achieve deyellowing via the same process. That is heating and bonding bromide with free oxygen then evaporating it from the surface.
I wonder if someone in Australia would be willing or has done the same a you did with an A1200.  At least with that you could get a new case
 

Offline paul1981

Re: Non-retr0bright de-yellowing.
« Reply #5 on: May 18, 2019, 11:54:09 AM »
Sorry about your Quadra case. I suppose now you'd wished you'd either left it alone or sprayed it white.  :(
 

Offline Dynamic_Computing

Re: Non-retr0bright de-yellowing.
« Reply #6 on: May 19, 2019, 03:36:23 PM »
I have tested the #LightBrighting technique here in Tucson, Arizona over the past few days, and can confirm it does work. Just remember, all things in moderation. If I left it out for a week or two, it would likely weaken and damage the case for sure. But two or three days? The difference is very noticeable on my A500 case and keyboard. I put a coin on the left side, right under the grill, as a control spot. You can see that the case is several shades lighter. So far, the plastic seems to be in the same condition it was before. This is a total of 16-20 hours of sunlight over three days.
« Last Edit: May 19, 2019, 03:49:12 PM by Dynamic_Computing »
 

Offline paul1981

Re: Non-retr0bright de-yellowing.
« Reply #7 on: May 20, 2019, 11:46:25 AM »
Can you do a follow up post in six months to see if it has reverted somewhat?
 

Offline spudmiga

Re: Non-retr0bright de-yellowing.
« Reply #8 on: May 21, 2019, 11:56:15 PM »
I tried this with my A500 plus a few days ago, the keyboard in particular had yellowed quite a lot.
Just after a day I could see the keys were less yellowed, without even taking a before photo. I will get it out in the sun again when I get chance (and when we have some sun here in Runcorn).
If it works, I am going to have to employ a security guard in my back garden with all this hardware outside  ;D
 

Offline paul1981

Re: Non-retr0bright de-yellowing.
« Reply #9 on: May 22, 2019, 10:03:40 AM »
I tried this with my A500 plus a few days ago, the keyboard in particular had yellowed quite a lot.
Just after a day I could see the keys were less yellowed, without even taking a before photo. I will get it out in the sun again when I get chance (and when we have some sun here in Runcorn).
If it works, I am going to have to employ a security guard in my back garden with all this hardware outside  ;D

Where do you live? I'll volunteer.  :D
 

Offline vince_6

Re: Non-retr0bright de-yellowing.
« Reply #10 on: May 22, 2019, 10:08:26 PM »
The pic in the middle is after 3 hours.
The one at the bottom is after 4 days, 3 hours treatment per day.

http://partsfromthepast.blogspot.gr/ A1200 Black Project
To blit, or not to blit?
 

Offline paul1981

Re: Non-retr0bright de-yellowing.
« Reply #11 on: May 25, 2019, 11:21:40 AM »
So let me get this straight - Heavy, pure unfiltered exposure to sun will turn plastics back to white, yet intermittent less powerful sun rays such as shining through windows onto your Amiga desk in the morning will turn them yellow? And too much exposure will actually cause them to go brittle (even if they do turn white)? It's all a bit confusing.
Some plastics turn yellow with age anyway right? I have this gel mousepad and the white plastic has turned yellow about 33% I believe from what it used to be yet it has never had any sunrays on it whatsoever.

So, that mouse for example...it looks much better now. How do you stop it returning yellow again? And from what I've read, any treatment will mean a return of the yellow much sooner than it normally would in getting there in the first place? Also, isn't they yellow just on the surface and not below it? I'm sure it rubs off with a bit of abrasive cleaning but at the cost of ruining the textured surface. I have a very yellowed Archimedes mouse so I do have an interest here.

Offline Wizard741

Re: Non-retr0bright de-yellowing.
« Reply #12 on: May 25, 2019, 12:51:06 PM »
Toothbrush + Toothpaste = White Color
 

Offline vince_6

Re: Non-retr0bright de-yellowing.
« Reply #13 on: May 25, 2019, 01:38:21 PM »
Yellowing is on top on a thin layer.
Also it comes back in a  2-3 months or a year.
I had a usb wifi card that turned yellow and used retrobright.
In 2 month period was like a canari again...
Even an A500 was back to yellow in a box.
Maybe just heat does the job.
http://partsfromthepast.blogspot.gr/ A1200 Black Project
To blit, or not to blit?
 

Offline Wizard741

Re: Non-retr0bright de-yellowing.
« Reply #14 on: May 25, 2019, 02:21:52 PM »
Read this (here in Russian, but very useful article) -

https://ksportal.ru/901-kak-otbelit-pozheltevshij-plastik.html