i found plenty of paint in the past that exactly matches the beige of a 90's computer case.

theres also a chance whatever you retro brighted might just be using a very bad plastic or you didn't do something right.

I am curious what conditions they were stored in.(edit: like, temperature, humidity, etc, not just sun exposure) I've heard so many different results with the process, it would be interesting to actually compile some evidence to see what leads to what.

Is there any kind of text or symbol inside any of them indicating what type of plastic it is?

I think the process with the most potential is the one that the 8 bit guy uses with computer keys. He adds peroxide to a pot of water and uses heat to de-yellow the plastics. I was looking into making a big vat that I could do bigger parts such as monitor casings and full computer cases in. It would have to be temperature controlled, and timer controlled for best results, so I would probably have to do a lot of experimentation to determine the optimal peroxide strength, temperature, and duration of the process.

I just disassemble the plastic parts and clean them like a dishwasher in hot water.
Staining residues (smoker condensates etc) are removed effectively.

But also consider the effects of lighting. With lower color temperature the staining becomes more apparent.
With an illumination of 3000K GE/Philips CDM (Ra 89), my mac keyboard looks really ugly, about the color of thick urine stain.
But at 4200K Osram HCI (Ra 95) it looks quite okay, even less ugly than the C64 beige.

emosun wrote:

i found plenty of paint in the past that exactly matches the beige of a 90's computer case.

theres also a chance whatever you retro brighted might just be using a very bad plastic or you didn't do something right.

do share this paint you used

Nothing I retrobrited approx 1.5 years ago has re-yellowed. Used liquid not cream and heat not light. Regular peroxide, too, not high-test.

Was thinking of getting a ozone generator and a heater and cabinet but not anytime soon.

Not retrobrighted anything as yet but I do intend to do the case and keyboard for my Amstrad 2086 just because they look like they spent the past 30 years in a smokers home. If it re-yellows at a later date then so be it, I think it's worth a shot.

I'll probably do it in a liquid solution since that appears to give the most consistant results.

I got the marble effect when i used the salon cream directly and wrapping the part in transparent plastic film like some of the instructions online say. Sometimes the marbled effect would disappear with a (very gentle) pass with a heatgun, but not always. I tried dissolving the salon creme in a container of hot water and placing the part in - this worked and didn't produce any marble effect, but required a much longer exposure to the sun because the light had a hard time penetrating the hazy water. I also noticed that any metal-plated surface like stickers and decals reacts with the mixture and produces a reddish substance. It happened on the branding of a Commodore datasette and a "Pentium III inside" sticker, causing them to start flaking off a little.

Next thing i want to try is using just a heater that recirculates the water in the container. It's much more convenient than relying on the sun, but i haven't landed on a convenient method of doing it other than using one of those pricy sous-vide kitchen appliances.

About re-yellowing - there's nothing you can do. If the plastic started yellowing after it was brand new, it will continue yellowing after retrobrighting - that's just how it was made. Of course, Amiga and C64c owners are in luck because they can buy one of those new kickstarter cases that are guaranteed not to yellow.

SETBLASTER wrote:

So how dificult is it to create a mold of an AT case front plastic, and replicate using good plastic? Paint is not good as i have not found a paint color that matches the original color, most of the paint is white like a wall.

For making something durable in ABS plastic or other types, then you need an injection mold. And those will never come cheap, and for just making one single item, it is kind of insane. Your best bet, is to keep on using the plastic that you have or just go with the closest colour to the original you can find. For recreating a certain tone, you can actually go for two layers applying the darkest colour first. That way you can finetune the nuance.

Or go to motip and find that colour you want, and then search for a seller.
https://www.motip.com/products/motip/do-it-yourself/

Colour guide:
https://www.motip.com/service/colourguide-motip/

I have never 'retro brighted' anything (but do clean everything). When something is yellow I either sell it or buy a new enclosure for it (I am not really attached to anything, everything has its price over here). The time that you need to spend to do a proper retro bright job is time you can spend on selling the item and get something else.

eh, if it is an item that's hard to find or you really like otherwise... retrobrighting can definitely be worth it

I've only done a couple things -- like the top half of an AV Famicom shell. At my latitude, there's not an abundance of sun, so I had to pick one of the rare gorgeous summer days we get and hope for the best. I used normal liquid hydrogen peroxide like you find at supermarket, because the cream stuff seems too concentrated and difficult to apply consistently. I think that's what causes the marbling issues. It lightened up a few shades after four hours or so, but the wind blew the large gallon baggy off my deck railing and it didn't get any sun after that. 🙁

That was summer a year ago, and it still looks fine.

I have two AT cases that are re-acquired childhood PCs. They will definitely be getting some retrobright love. Given the extent of yellowing (they're really yellow -- like a manilla envelope), any bleaching would be an improvement. It can't be any worse than it is now, and if it turns out terrible (or just doesn't work), then paint is the next logical step.

Interesting topic. A few weeks ago, I bought Salon Creme (40%) from a Dutch hair salon site because I found a Dutch topic about how well that particular brand worked. I'm waiting for more sun to try it (I'm told by friday, it will be sunny so I'll try to get it done by then).

I saw the 8bit Guy vid where heating the water would work great but that doesn't work for large parts and my main use would be to de-yellow a keyboard frame as well as the front of my Pentium III case which is seriously yellowed compared to the (metal) side plates. I'm curious to see what the result will be.

About the marbling: this I don't quite get. Does peroxide cause the plastic to whiten beyond its original shade? Because if it doesn't, simply giving it a second coat should solve that?

I also considered the spray paint method but there's some issues I have with that:
- paint effectively adds another layer on top of plastic that wasn't designed to be painted so stuff like buttons may start to stick and anything that rubs against the sprayed plastic may cause the paint to flake or scuff (think sliding panels, removing or adding drives, ...)
- paint tends to pool - a lot of older cases have grooves, "sharp" edges, a grained texture, ... but paint would easily affect all of those - the grained texture would be gone, sharp edges would soften, etc.

It may be a solution for specific parts like 5.25" panels, loose buttons, etc. b

I also saw the 8-bit Guy video on this subject. I was impressed with the idea of using an ozone generator and inflating a plastic bag, then leaving it out in the sun... that way, no messy liquids involved or anything. Don't even have to remove the case, just find a large enough Ziploc and plop the whole thing in there.

It's something I want to try at some point. Beats me whether I can find a suitable ozone generator for cheap.

So I decided to give that salon creme a go but instead of rubbing it on, I added it to water, stirred it well, heat up the water to near boiling and added a small plastic part of the HP Vectra case which had badly yellowed compared to the other plastic on the front. I let it simmer for 90 minutes, took it out, examined it and thought "hmm it's still quite yellow" but then I took it upstairs, inserted it back into the case and now it's almost the exact same colour of the case so it shows how eyes can be really deceived. Tip: find something with a similar colour and use it to compare.

Note: I did not use much creme at all. Each bottle I have (I bought 3) is 1L and I maybe used 1cl of that. I could have added way more into the pot but since this was a test I didn't want to risk anything too important. If it failed, I would have just spray painted it since it's just a tiny plaque. But if it works with this little cream (and I assume the cream is already weakened by making it gel-like) then you really don't need to cover items in this stuff. The 8 bit guy said he used 4 hours for his key and the damn thing looked like it was related to Michael Jackson!

SETBLASTER wrote:

So how dificult is it to create a mold of an AT case front plastic, and replicate using good plastic? Paint is not good as i have not found a paint color that matches the original color, most of the paint is white like a wall.

Look at plastic modeling as a guide, they do oodles of things more intricate, you learn some of their skill set and replicating much simpler pc parts shouldn't be a problem. Also check out Adam Stavage's videos: https://www.youtube.com/watch?v=9XB4Be6TjHU

Rather than mere part replacement you can then think of enhancement, like making an old style monitor casing for an lcd for example.

I love my yellow computers. Stay away from them with your crazy chemicals!

Errius wrote:

I love my yellow computers. Stay away from them with your crazy chemicals!

I envy you :p The discoloured front of my Pentium III actually puts me off using it - it's ridiculous yet it's true. It looks so tacky and ugly with the uneven yellowing.

meh, it's all a matter of personal taste. I, personally, value appearance pretty high, so I do like retrobrite. However, the current processes do have the potential to cause damage, so I am refraining from retrobriting everything at the moment until the process is refined a little further. I believe the 8 bit guy is still doing some testing on stuff to determine the optimal process.