Indy case discolouration

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squire
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Indy case discolouration

Unread postby squire » Thu Feb 01, 2018 2:06 pm

Hi everyone,

total SGI-noob here. I've been toying with the idea of acquiring an Indy for quite a while now. The pizzabox form factor is still my favourite and I think the Indy has a very striking appearance. I prefer it to every other SGI-Model, despite being rather low-powered compared to some of the other machines. Anyway, every once in a while I search the internet looking for a bargain.

Now, what I've noticed more often than not, is that the Indy seems to be prone do discolouration of the blue plastic. For instance one can often see a mark where a monitor-base once stood blocking the sunlight, whereas the area around it can be much darker. I'm assuming that what happens is the same thing that tends to happen to traditional beige pc-plastics with too much sunlight exposure, only that due to the blue colour it doesn't turn yellow, obviously, but rather gives the plastic a darker appearance.

Has anyone ever tried the retrobrite approach involving mainly hydrogen peroxide and UV-light on an Indy case? Do you think it would work?

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vishnu
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Re: Indy case discolouration

Unread postby vishnu » Thu Feb 01, 2018 2:24 pm

Project:
Temporarily lost at sea...
Plan:
World domination! Or something...

:Tezro: :Octane2:

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Re: Indy case discolouration

Unread postby jan-jaap » Thu Feb 01, 2018 2:38 pm

IIRC retrobright works less well on granite keyboards and mice than beige ones. Same might be true for the blue of Indys. Also, you don't want your Indy to look like a stone-washed jeans ...
:PI: :Indigo: :Indigo: :Indy: :Indy: :Indy: :Indigo2: :Indigo2: :Indigo2IMP: :Octane: :Octane2: :O2: :O2+: Image :Fuel: :Tezro: :4D70G: :Skywriter: :PWRSeries: :Crimson: :ChallengeL: :Onyx: :O200: :Onyx2: :O3x02L:
To accentuate the special identity of the IRIS 4D/70, Silicon Graphics' designers selected a new color palette. The machine's coating blends dark grey, raspberry and beige colors into a pleasing harmony. (IRIS 4D/70 Superworkstation Technical Report)

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squire
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Re: Indy case discolouration

Unread postby squire » Thu Feb 01, 2018 2:48 pm

Thanks for the pointer, vishnu! I actually tried the search yesterday, but I only searched for "retrobrite" and not for "hydrogen peroxide" thus missing the
Restore your yellowed plastics? topic with zackwatt's report, who experimented on an indy.

jan-jaap wrote:IIRC retrobright works less well on granite keyboards and mice than beige ones. Same might be true for the blue of Indys. Also, you don't want your Indy to look like a stone-washed jeans ...
:lol:

I'm actually trying to sidestep the issue by looking for an indy in at least "nice condition", so to speak. Although chances of finding one that's not outrageously overpriced seem to be rather slim these days. Just in case I come a across an Indy at bargain price level, I might actually consider experimenting on the plastic if it's not too extreme. What's almost worse is the amount of scratches these machines have sometimes suffered. Why are people so careless... :roll:

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Re: Indy case discolouration

Unread postby marshallh » Thu Feb 01, 2018 3:15 pm

retrobrite does NOT work on cases they are not white/beige colored. Yes, I've tried...
It has a mottled bleaching effect and causes white streaks. It is VERY noticeable and far worse than having gross dark plastic.


There are basically 2 types of UV damage I've observed:
1. Intrinsic oxygen exposure damage - mere exposure to atmosphere/heat causes the plastic surface to darken and yellow both inside and out. This will happen even if the case is stored in a cool, dry dark place without any light.

2. Exposed UV damage - cumulative exposure to UV sources such as outdoor light, full spectrum incandenscents, CCFL lights. Scattered/reflected light still counts. Plastic becomes yellow and darker only in the places with exposure. The inside of the case will always be the original color.

Of course, you can have both at the same time. But usually it's one or the other if it was well maintained.

If you get a mint SGI and stick it in your bedroom/office, it WILL become yellowed eventually because of your windows letting outdoor sun in (Even blinds/shades won't stop it). If you want to use one everyday, find an ugly one that won't get worse.

Also, black/charcoal plastic can still become yellowed, it just takes longer to notice.

There are 2 "fixes":
1. Paint - there are many types of paints, finishes, and application methods. All of them will change the surface finish. All of them will change the sheen from a matte textured finish (standard with ABS cases) to a more plasticky, fake looking orange peel texture. Eventually if you keep applying coats you will end up with a glossy smooth finish, which is nice on a car but not on a computer case. Sufficient coverage will require multiple coats making this a poor option.

2. Dye - there are special types of plastic-bonding dyes that actually change the outer layer of plastic where the damage occured, rather than covering it. Good binding dyes are sprayed with an atomizing paint gun and generally have superior UV protection. As the coats are much thinner than paint, it has less effect on the textured finish, leaving that original. Unfortunately dye is not able to make significant color changes in 1 step. For example, to move to a lighter (original) color you would dye with a white/light gray and then your final color. It is possible to get custom color matched dye based on a sample piece. I am still working on this method.

Of course, both methods will require removal of any silkscreened logos on the plastic. Luckily a skilled graphic designer can re-create these given enough source marketing literature PDFs. Creation of new patterns can be done with plastic-bonding screen printing methods - screen printing encompasses a lot of end uses and direct plastic printing is just one. I believe it is possible to re-brand a case with new logos at equal or better fidelity than the originals given sufficient materials and experimentation.

So there's what I know on the subject - I have a very sun damaged, dark nasty Tezro that I will be experimenting on once I get my HVLP rig back up and running.

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Re: Indy case discolouration

Unread postby squire » Mon Feb 05, 2018 3:01 pm

Your reply certainly makes me appreciate my ancient Sparcstation clone ever so strongly. Full steel case pizza box, built like a tank and no plastic at all. They just don't make 'em like they used to... The only thing that suffered light yellowing was the manufacturer's logo sticker on the front.

I'd like to point out the following reply from the topic I linked above, though:
zackwatt wrote:My findings were the process removed the yellow caused by the sun, if the plastic was also bleached from the sun, you will end up with a lighter piece. My keyboard was lighter where the sun damaged it, and the same, unchanged OEM color where the sun did not damage it.

Also, My retrobright process did not bleach the teal Indigo case at all, it only brought out the strong original color.

It was an Indigo, not an Indy (my mistake). But that doesn't sound so bad, does it?

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Re: Indy case discolouration

Unread postby Dodoid » Mon Feb 05, 2018 4:03 pm

marshallh wrote:Luckily a skilled graphic designer can re-create these given enough source marketing literature PDFs.


Many (I would even dare say most) SGI logos are available on the Nekochan FTP server as vector graphic EPS files. These are very useful for things like your silkscreen plans or the Mini Indigo.
:Onyx: :O2000: :Fuel: :Octane: :Octane: :Octane: :O2: :O2: :Indigo2: :Indigo2: :Indy: :Indy:
and a small army of Image


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