Announcement

Collapse

Forum etiquette

Our mission ...

This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.


Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.


Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.



Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • Use the Private Message system for posts that are targeted at a specific person.


"PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.


Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.


Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.


New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.


Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

Retr0Bright: Does re-yellowing occur even in the absence of UV light?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Retr0Bright: Does re-yellowing occur even in the absence of UV light?

    As some of you know, I've done a bit of Retr0Brighting in my time.

    Many of my treated cases and plastic bits are regressing, even in the apparent absence of UV light. I thought this was an interesting find, so wrote it up. See:
    http://www.classic-computers.org.nz/...-temporary.htm

    I'd be interested to know if anyone else has experienced this phenomena.

    Tez
    ------------------------------------------------
    My vintage collection: https://classic-computers.org.nz/collection/
    My vintage activities blog: https://www.classic-computers.org.nz/blog/
    Twitter: @classiccomputNZ ; YouTube Videos: (click here)


    #2
    My Mac Plus got yellowed, even though it has spent nearly all its life since I got it in the mid-'90s in a dark corner of my basement, shielded from any direct light. And my Commodore 128 was the worst case of yellowing I ever experienced, even though it almost never left the cardboard box it was sitting in, totally blocked from any light!

    Comment


      #3
      I thought I had read that the yellowing was caused by the oxidation of the flame retardant in the plastic?
      This space intentionally left blank [ ].

      Comment


        #4
        Originally posted by arrow_runner View Post
        I thought I had read that the yellowing was caused by the oxidation of the flame retardant in the plastic?
        As far as I know it is, but I'd always assumed (maybe wrongly) that a reasonable amount of UV light was needed to facilitate this. Based on what's happened it may be that very little UV (if any) is needed. I too have heard stories about people putting white cases into dark storage and years later bringing them out yellow. In the case of my Retr0Brighted cases....just a few days exposure per year under florescents (i.e. the time I had the computers out of the box to play with or test) seemed to be all that was needed.

        Merlin, in his writeup in the Retr0Bright wiki does say even low levels from florescent lights is enough. I'd always assumed this was everyday exposure though.

        There is something more puzzling. Let's assume yellowing can occur in the absence of much (or any) UV light. Why then are those cord markings on the Apple IIe and Vic 20 reappearing? You would have expected any further yellowing of my cases, even with low levels of UV, to be consistent across the case surface now the cords are not there. All surfaces would be exposed to equal amount of oxygen or brief light. However the cord impressions (which protected the plastic under them from initial yellowing) are re-appearing?

        The question I have in my mind therefore is "do the changes in the chemical structure cause by the initial yellowing (OR perhaps the RetroBrighting itself) make the plastic MORE prone to future 2BR.O co-ordinant bonds or/and migration of these to the surface of the case (hence causing yellowing)? " Or is something else going on?

        Whatever is happening, the practical implications are that even brief and very very low levels of UV seem to be enough to re-yellow retr0Brighted surfaces over time. There is not enough evidence in my case to say that UV is not needed AT ALL, as all the units had been exposed briefly a few times a year, to fluorescent light.

        Tez
        ------------------------------------------------
        My vintage collection: https://classic-computers.org.nz/collection/
        My vintage activities blog: https://www.classic-computers.org.nz/blog/
        Twitter: @classiccomputNZ ; YouTube Videos: (click here)

        Comment


          #5
          Originally posted by tezza View Post
          The question I have in my mind therefore is "do the changes in the chemical structure cause by the initial yellowing (OR perhaps the RetroBrighting itself) make the plastic MORE prone to future 2BR.O co-ordinant bonds or/and migration of these to the surface of the case (hence causing yellowing)? " Or is something else going on?
          Just a further observation, I notice that the RX8000 case is yellowing quite evenly, even on the part that was initially protected from sunlight by a monitor stand. It is now more yellow that it was originally, although you can still make out the circle so the yellowing there hasn't progressed quite as much as the rest of the case.

          Tez
          ------------------------------------------------
          My vintage collection: https://classic-computers.org.nz/collection/
          My vintage activities blog: https://www.classic-computers.org.nz/blog/
          Twitter: @classiccomputNZ ; YouTube Videos: (click here)

          Comment


            #6
            Perhaps the cause of re-yellowing is not so UV light but a natural degradation or breakdown in the pigments or dyes used in these plastics. Even in the dark basement, the plastic is still exposed to oxygen or lack thereof, moisture (dank basements), low levels of radiation (closer to the earth), heat, cold, static electricity, smoke, dust, etc. Perhaps they accelerate the re-yellowing. Could the retro-bright agents be breaking down.
            My Retro Computing and Vintage Gaming Blog : http://nerdlypleasures.blogspot.com/

            Comment


              #7
              I do remember, when retrobright was first publicized, there was a recommendation to coat pieces with clear acrylic lacquer to seal it against oxygen and prevent re-yellowing. It was just a minor footnote, and thus never really came up in discussions much... but perhaps that little detail was a bit more important than it seemed to be at the time.

              Comment


                #8
                By the looks of things, retrobrite was a waste of time.
                GEEKS WITH A GRUDGE!

                Comment


                  #9
                  For solid areas without any decals on them, why not just paint the plastic the desired color?

                  Comment


                    #10
                    Originally posted by Great Hierophant View Post
                    Perhaps the cause of re-yellowing is not so UV light but a natural degradation or breakdown in the pigments or dyes used in these plastics. Even in the dark basement, the plastic is still exposed to oxygen or lack thereof, moisture (dank basements), low levels of radiation (closer to the earth), heat, cold, static electricity, smoke, dust, etc. Perhaps they accelerate the re-yellowing.
                    Yes, but if it was natural degradation or breakdown (or just oxygen) the insides of these cases would also be yellowing. They are not. The insides are not yellowed at all. Only the areas that were originally yellowed (and also treated with Retr0Bright) are now re-yellowing.

                    Originally posted by Great Hierophant View Post
                    Could the retro-bright agents be breaking down.
                    Well, if this yellowing is higher than it normally would be under the given light conditions then it's a result of the plastic already being damaged somehow by either the initial yellowing, or the Retr0Bright itself. I'm thinking it could be the former. Presumably a yellowed case has lots of these small 2BR.O co-ordinate bond molecules throughout the plastic. However Retr0Brighting only deals with the very top layer, and if they are already pre-formed lower down, all they need to do is find their way to the surface? (in which case would sealing against Oxygen really help anyway?)

                    Does this sound a reasonable hypothesis? Any plastics chemists out there?

                    Tez
                    ------------------------------------------------
                    My vintage collection: https://classic-computers.org.nz/collection/
                    My vintage activities blog: https://www.classic-computers.org.nz/blog/
                    Twitter: @classiccomputNZ ; YouTube Videos: (click here)

                    Comment


                      #11
                      Originally posted by tezza View Post
                      Well, if this yellowing is higher than it normally would be under the given light conditions then it's a result of the plastic already being damaged somehow by either the initial yellowing, or the Retr0Bright itself. I'm thinking it could be the former. Presumably a yellowed case has lots of these small 2BR.O co-ordinate bond molecules throughout the plastic. However Retr0Brighting only deals with the very top layer, and if they are already pre-formed lower down, all they need to do is find their way to the surface? (in which case would sealing against Oxygen really help anyway?)
                      The more I reflect on this, the more it fits all the evidence.

                      Here is the hypothesis. The original damage from light causes degraded or free bromides throughout the case from the fire retardants. Retr0Bright only takes these away from the top layer. However these bromides can migrate fairly freely through the polymer. They don't need light to do this. Migration is probably accelerated in hot conditions. They migrate to the top and within a few years the surface is yellowed again.

                      If this hypothesis is correct then a UV sealant will not protect the case. Or any sealant maybe. Unless pre-formed bromides from previous light damage can be stopped from migrating to the surface (and I don't know how you would do that) Retr0Bright is only ever going to be temporary.

                      Sound logical?

                      Tez
                      ------------------------------------------------
                      My vintage collection: https://classic-computers.org.nz/collection/
                      My vintage activities blog: https://www.classic-computers.org.nz/blog/
                      Twitter: @classiccomputNZ ; YouTube Videos: (click here)

                      Comment


                        #12
                        This is disappointing news. I was going to give Retr0Bright a try on one of my IIes. Now, I'm inclined to spray paint it, as suggested by vwestlife. I'd appreciate any suggestions regarding preparation and paint. Or would you prefer that I pursue this in another thread?

                        Comment


                          #13
                          Originally posted by Gib View Post
                          This is disappointing news. I was going to give Retr0Bright a try on one of my IIes. Now, I'm inclined to spray paint it, as suggested by vwestlife. I'd appreciate any suggestions regarding preparation and paint. Or would you prefer that I pursue this in another thread?
                          Indeed. Disappointing.

                          Bear in mind that the theory above (pre-existing bromines from the original damage migrating to the surface) is only a theory. It would need testing and research to prove or disprove. It does seem to fit with what we know about yellowing and my results though.

                          Tez
                          ------------------------------------------------
                          My vintage collection: https://classic-computers.org.nz/collection/
                          My vintage activities blog: https://www.classic-computers.org.nz/blog/
                          Twitter: @classiccomputNZ ; YouTube Videos: (click here)

                          Comment


                            #14
                            Originally posted by tezza View Post
                            Yes, but if it was natural degradation or breakdown (or just oxygen) the insides of these cases would also be yellowing. They are not. The insides are not yellowed at all. Only the areas that were originally yellowed (and also treated with Retr0Bright) are now re-yellowing.
                            I would assume that the inside of cases see a lot less oxygen movement.

                            Have you presented your findings to the chemist(s) who originally came up with retr0bright?
                            Offering a bounty for:
                            - A working Sanyo MBC-775 or Logabax 1600
                            - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

                            Comment


                              #15
                              Originally posted by Trixter View Post
                              I would assume that the inside of cases see a lot less oxygen movement.

                              Have you presented your findings to the chemist(s) who originally came up with retr0bright?
                              Well, I'm not so sure. 99.9% of the time these computers were sitting deep in buried boxes. I wouldn't imagine there would be any oxygen movement to speak of, either in or out.

                              Yes, I did send a PM to Merlin this morning. Merlin introduced Retr0Bright to VC, and did most of the work on the wiki. I think he is a chemist. I'd love to hear a chemists opinion on the theory and also like to hear about the status of machines that were Retr0Brighted about the same time mine were.

                              Tez
                              ------------------------------------------------
                              My vintage collection: https://classic-computers.org.nz/collection/
                              My vintage activities blog: https://www.classic-computers.org.nz/blog/
                              Twitter: @classiccomputNZ ; YouTube Videos: (click here)

                              Comment

                              Working...
                              X