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So I have various old computers and peripherals that could use retrobrighting. However, after researching, I have more questions than answers. What type of cleaner/degreaser is best to use or avoid? Is gel, liquid, or gaseous hydrogen peroxide better? If liquid, what is the best ratio of water to hydrogen peroxide? What is the best temperature to keep it at? What is the best wavelength of UV light? What wattage equivalent is best? What method of DIY retrobright box works best? Every guide and YouTube video has different information, but all really lack any real information all together.

Is there a definitive guide? I doubt it, but maybe I just havent found it. Has anyone done any real scientific testing? Or is everyone just seeing what other people have done and winging it?

What about post retrobright? Does UV protectant actually help?

There are apparently conflicting statements about whether retrobrighting causes brittleness, and even as to what causes the yellowing and what retrobrighting actually does. Does this actually vary, or are there just conflicting theories?

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    ay, are yu about preserving history, or making a quick buck? If the first, then you shouldn't even think about retrobrighting. Beside removing history it'll be damaging the very substance, making it brittle and fall apart soon.
    – Raffzahn
    Commented Oct 29, 2022 at 9:59
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    @Raffzahn Im not saying you are right or wrong, but show me a scientific study that says that is the case. Heck, show my anecdotal evidence that your statement is true.
    – Keltari
    Commented Oct 29, 2022 at 14:34
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    @Keltari At the very least, I can point to Modern Classic's video for the "removing history" part and, for the "damaging the very substance" part, I don't know about heat-activated methods, but UV photodegradation of plastics is a well-known known phenomenon. In fact, that's why I've been looking into the details of retr0brite... to figure out whether heat-based versions of the process are equally hard on the plastic and whether there's a way to stabilize the plastic against further degradation without bleaching it, preservationist style.
    – ssokolow
    Commented Oct 29, 2022 at 14:54
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    Basically you aren’t going to undo the damage to plastic from UV exposure. Can’t be done - UV causes cross linking (hence the brittleness). Anything that attacks the cross links also attacks the main chains so the outcome is ugly.
    – Jon Custer
    Commented Oct 29, 2022 at 16:18
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    I've converned this QA to be a community wiki. My gut feel is that the question is way too broad, but as a Retro Computing resource I feel like we'd be remiss not to have something covering all aspects of retrobrighting, even if they are links to competing theories/processes.
    – Matt Lacey
    Commented Oct 31, 2022 at 16:03

2 Answers 2

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TL;DR Because there are so many variables, anecdotal information is all you can count on. If you wish to retr0bright in order to make your classic machine more "display-worthy", then be prepared to experiment and to risk some undesired results.

Based on my own experience with performing this process dozens of times on many different classic computers with differing plastics, I'd offer the following lessons (not an exhaustive list!).

  1. Proper storage will greatly diminish the rate of (re-)yellowing of plastics. By this, I mean a cool, dry, and dark storage location. The yellowing is primarily caused by UV and heat. Hot attics with direct sunlight are probably the worst.

  2. Many different types of plastics were used for classic machines. Even amongst very similar models, the plastics will vary, and that's before accounting for the differing histories of individual samples. So, you really cannot expect every retro-brighting attempt to go the same.

  3. If the plastics are brittle to begin with, don't bother trying to retro-bright. Trying to improve the look of physically damaged plastics is likely a fool's errand.

  4. The submersion in hydrogen-peroxide technique has proven the safest for me to avoid streaking. The 8-Bit Guy (YouTube) has many videos demonstrating this, and it seems to be his favorite technique.

  5. Using direct sunlight alone is a slower, but still effective means of reducing yellowing. I've even used this to "smooth out" the streaking effect caused by retro-bright attempts that went poorly.

  6. It's very important to start with the plastics being very clean and to try to make the exposure to light/heat/chemical as even as you can across the whole surface. This is why submersion within a clear container in direct sunlight is overall easiest.

  7. Finally, I only bother with retro-bright for badly yellowed machines that are plain ugly and nothing like their original color. If it is just a bit off, then the yellowing is mostly only noticeable if compared directly to a non-yellowed machine or photo showing original color.

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  • Point 2 is very true and also a reason why a one-size-fits-all solution is rather difficult. My Amiga 1200 has not yellowed at all, apart from a handful of keys on the keyboard - the rest of the keys have not yellowed either.
    – Edders
    Commented Oct 31, 2022 at 12:12
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I don't have a single definitive guide, but I'd say these videos together serve that purpose well together.

If you don't have time to watch them all, watching the Modern Classic and Hey Birt! videos should serve well as a minimum recommended set.

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