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Atari 800 Restoration. Retrobrite or paint.

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22 minutes ago, Jetboot Jack said:

I figure you have old equipment, it won't look new after nearly 40 years...

Really just depends on the chemical properties of the plastic. I do have plenty of stuff that old that hasn't yellowed or noticeably aged at all. Other things I have are now the color of a New York taxicab. As a consumer, there's really no way to know which way something's going to go over time.

 

And while I definitely do think light and heat can cause yellowing for plastic that's prone to it (my Apple IIc didn't really yellow at all for 20 years until I put it in a hot attic, and now it's like an orange), sometimes it just seems to happen for no reason other than time. But the plastic needs to be prone to it, and not all plastic is. My IBM 5150, for example, is 36 years old and looks brand new. So does my Magnavox monitor (aka the Commodore 1084). Some plastic just doesn't yellow.

 

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19 minutes ago, Preppie said:

Nothing wrong with growing old gracefully :)

 

Well, gracefully I take, for sure... but "gracefully brownish" not so sure about it... ;-)

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@Jetboot Jack:  I bought an STE that was a really dark greenish brown.  A little over 2 hours in the sun with 40 Volume hydrogen peroxide cream turned it back to the original light gray.

 

Before and after pics of a badly yellowed 800 after retrobrighting with jamm's method.  It took several days.

 

The last pic is after reassembly.  It is the one on the top left of the shelf.

 

...and yes, I kinda like 800s.  I have another one arriving tomorrow (hopefully).

 

 

before_after_6.png

before_after_6b.png

beige_sm.png

Edited by Colleton
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So this 1200XL is the one I restored in a rather intense, invasive and hard core process 3 years ago (June - September 2017). The case started off looking like this:

 

1200XL_pre_peroxide.jpg

 

I used 40vol creme conditioner from Sally's, plastic wrap and June Tennessee sunlight to get it looking like this (comparison with the bottom I had not yet done):

 

1200XL_peroxide_day1.jpg

 

Almost 3 years later, this photo just tonight. I've added a bunch of other "white" stuff for comparison and to account for white-balance issues with the photo. The 1050's in the picture have not been treated in any way. And yes. This is the exact same 1200XL shown above.

 

IMG_4166.JPG

Edited by DrVenkman
Formatting
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On 4/23/2020 at 2:03 AM, Colleton said:

@Jetboot Jack:  I bought an STE that was a really dark greenish brown.  A little over 2 hours in the sun with 40 Volume hydrogen peroxide cream turned it back to the original light gray.

 

Yes green-ish brown, like slimy mud - mine looks NASTY!

 

     sTeVE

 

P.S. Nice collection!

Edited by Jetboot Jack

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I personally use the sun, speak only the sun ... I use "Solar-Bright" ing ... Before cleaning the ATARI (please do not clean it in the dishwasher, but manually!), Then in the sun for a few days , "rotate" every 6-8 hours and detach from the surface and is good. Retrobright breaks the plastic. I know some will shake their heads now, but just wait and see. I have seen many enclosures in the past few decades, but I have never seen an enclosure that lasted longer than 24 months after using H2O2! Painting is also an option, but for me as a collector it is a "NoGo". I had 800XEs here myself, which were a Gilb color, like an ATARI400, because of "Solar Bright" they look like new. You don't need chemistry ... Just the deceptive fact that there are (unfortunately) ozone holes that (and this was explained to me by an ex-student of chemistry) that reversed the oxidation process at that time. I don't know if that's really the reason, I don't doubt, I don't advocate either - I just don't know. What I do know, however, is that I have yellowed a lot of 600XL, 800XL, 65XE, ST (e) enclosures and their peripheral enclosures !!!

 

And yes, since it is very sunny here in Germany again, the entire garden is under my fittings. Of course, my wife is happy ;-) Housing parts everywhere, not just ATARI, also speaker boxes, other old computers, etc. Had 2 1050 cases outside for 2 weeks, they now look like new, coming tomorrow the next 1050s out, I'll see if I take pictures of them beforehand and then afterwards ...

Edited by dash_rendar
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6 hours ago, dash_rendar said:

I personally use the sun, speak only the sun ... I use "Solar-Bright" ing ... Before cleaning the ATARI (please do not clean it in the dishwasher, but manually!), Then in the sun for a few days , "rotate" every 6-8 hours and detach from the surface and is good. Retrobright breaks the plastic. I know some will shake their heads now, but just wait and see. I have seen many enclosures in the past few decades, but I have never seen an enclosure that lasted longer than 24 months after using H2O2!

Are you kidding? I have at least five computers that I've retrobrited myself several years ago and they are exactly the same as they were. This is not an uncommon procedure anymore. I guarantee you half the people in this thread have stuff that's lasted a lot longer than 2 years (and counting) after retrobriting.

 

Some plastic gets brittle over time. But it's got nothing to do with retrobrite. Those things would be brittle with or without retrobrite. Stuff that's not brittle doesn't suddenly get brittle with retrobrite. It's a myth.

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15 hours ago, dash_rendar said:

I have seen many enclosures in the past few decades, but I have never seen an enclosure that lasted longer than 24 months after using H2O2!

You didn’t see my post only two posts above yours? That 1200XL was done in June 2017. The last photo was taken 3 minutes before I posted. That’s 34 months in case your math is rusty.

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It spent 4 hours tanning today. No lotion. And, I think it looks a little better. The temps are mild. So I just set it on the picnic table and rotate it around every hour. May have another session Wednesday.

 

IMG_4703.JPG

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I put a top shell out in the sun yesterday.  When I put it out again today, I realized that I forgot to put the ram cover/cart door out.  I was amazed at the difference between the two after just one day!  They are both out there now.  I hope that they even out.  I should probably put the bottom shell out, too, but it has a bunch of stuff sitting in it.

 

Question:  Should I put the keyboard out in the sun?  Will it help lighten up the lettering on the dark keys?

 

Q2:  Is it OK to put 1050s in the sun while assembled, or should I take them apart and just put the upper & lower shells out?

 

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I disassemble them and only put the case parts outside.  While the case parts are outside the machines get disassembled for cleaning, recapping, repair, etc...

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I would really love to understand how the same processes (heat and sunlight) that seem to turn the plastic yellow over time, seem also to undo the change when done intensely over a short period of time.

 

Are there any chemists in the house?

 

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It's not the heat but the sunlight that is de-yellowing. Part of the cause is that indoor light is not full spectrum. Some indoor lights may be fine while other types (compact fluorescent) seem to be much worse. Suggest you watch Retro Recipe's video when he first covered the topic. Some of the science was discussed.

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Just sandblast the bugger complete without disassembling and then spraypaint it without masking it mate! Neon Multicolour would be ideal. Lol. Post your pics when done! :)

Edited by YSG2020

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On 4/28/2020 at 2:39 AM, jamm said:

I would really love to understand how the same processes (heat and sunlight) that seem to turn the plastic yellow over time, seem also to undo the change when done intensely over a short period of time.

 

Are there any chemists in the house?

 

Scientific literature on the effect of various wavelengths of light on degradation of ABS and similar polymers suggests the following:

 

1) Age and heat mediated yellowing is accelerated by UV light, both UVA and UVB across the spectrum

2) Weakening is similarly accelerated by UVA & UVB but as the plastic ages and yellows, visible light also becomes increasingly damaging

3) Bleaching out of yellowing is due to visible light at the blue/violet end of the visible spectrum

4) Yellowing is accelerated by dark because, particularly in normal indoor lighting conditions behind glass, the bleaching effect of visible light exceeds the yellowing effect of UV light

5) Normal glass filters UVB completely but UVA only partially. Laminated glass/windscreen/windshield glass or UV-filtered glass completely filters out UVA also

 

The conclusion to be drawn from this is that in theory the best and safest way to reverse yellowing without damaging the plastic should be by exposure to bright light  in the visible spectrum e.g. bright daylight behind laminated or UV-shielded glass.

 

Note that although the windshield/windscreen of a car is usually UV-shielded, side windows usually are not and the dash of a car in full sunshine might get VERY hot unless it is very well ventilated.

 

Refs.

Searle, N. D., Maecker, N. L. and Crewdson, L. F. (1989), Wavelength sensitivity of acrylonitrile–butadiene–styrene. J. Polym. Sci. A Polym. Chem., 27: 1341-1357. doi:10.1002/pola.1989.080270418

Abstract

The wavelength sensitivity of unpigmented 100 mil thick ABS exposed to sunlight and filtered xenon are radiation was determined by the sharp cut filter technique based on three types of photochemical changes: bleaching, yellowing and loss in impact strength. Bleaching of the yellow‐colored species formed in the processed material is caused by wavelengths between 380 and 525 nm with maximum color change by the 475–485 nm region. Photochemical yellowing is due to wavelengths between 300 and 380 nm with all wavelengths being almost equally effective. The spectral sensitivity based on change in impact strength shifts from the UV to the visible region as photochemical yellowing progresses.

 

Pickett, James. (2004). Reversible post-exposure yellowing of weathered polymers. Polymer Degradation and Stability. 85. 681-687. 10.1016/j.polymdegradstab.2004.03.008.

 

Abstract

The commonly observed effect of weathered polymer samples continuing to change color in the dark was studied in some detail for polycarbonate, styrene–acrylonitrile copolymer (SAN), and various combinations with SAN–polybutadiene rubber graft (SRG) copolymer. All of the formulations became more yellow upon storage in the dark after accelerated weathering, and all behaved very similarly. There was a fairly rapid shift of 1–2b units (as defined in CIELAB color space) over the first two weeks followed by a slower, linear shift that continued for many months. This amount of color shift is enough to be visible to the eye in side-by-side comparisons. Most of the additional color generated in the dark could be bleached by exposing the samples to sunlight through a south-facing window. The samples usually reached the original color after 2–4 days of window exposure. Putting the samples back in the dark caused the yellowing to start up again, although the rapid yellowing often was not as much as the first time. Samples aged under natural conditions outdoors also underwent a small color shift upon storage for 5 months and substantial color shifts after two years.

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This is always going to be a subject of contention, with people rigidly taking a side.

 

About 2 years ago (give or take a few months) I spray painted a 1050 case for use with my first 1088XLD prototype. To this day it still looks beautiful, and can be seen in several posts and videos through out the development and testing cycle, as well as on the 1088XLD page on my website. And believe me this unit got knocked about and disassembled and then reassembled a multitude of times throughout the process. And as I sit here nearly 2 years later and look at it sitting on my desk, it still looks like brand new. And best of all it won't re-yellow with the passage of time, like all retrobrighted systems will eventually do.

 

The key to painting, is to do multiple light coats, so as not to fill in the natural texture of the plastic. And most importantly choose a color that's close to original, so if any nicks do occur, they won't  be obvious.

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I know I am gonna go against the wind, again.  But why don't people just leave well enough alone.  Let the antique's  true patina just shine in its own glory.   Then again, I am the one that everyone hates because I say that 1 Meg of memory on a 64K machine is not really used.   Let's get get mad again.

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There are a lot of variables involved, including the condition of the particular piece of plastic involved, the degree of yellowing it's undergone, whether or not the yellowing is even, and, of course, personal preferences. 

 

I'm sure it's possible to do a good job with painting, I simply wouldn't trust myself to get it just right, and it would bug me forever to get it wrong.

 

Brightening out in the sun would certainly melt the case into a puddle out here in Arizona - at least for 9 months out of the year - so there's no way I'm going that route, although it's obviously worked well for some people.

 

I've had great luck brushing salon developer on the case and letting it sit indoors for a day or two, so I'll stick with that method until it fails me.  🙂

 

Leaving it alone is always a safe option, but having seen the results of getting it right, I personally would go for some type of de-yellowing process unless it looked like it'd be particularly risky for some reason.

 

Every case and every case owner is a special, unique snowflake. ❄️

 

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2 hours ago, jamm said:

Every case and every case owner is a special, unique snowflake. ❄️

I'd say the cases are quite durable, and it's the owners that are the delicate little snowflakes :)

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2 hours ago, jamm said:

There are a lot of variables involved, including the condition of the particular piece of plastic involved, the degree of yellowing it's undergone, whether or not the yellowing is even, and, of course, personal preferences. 

 

I'm sure it's possible to do a good job with painting, I simply wouldn't trust myself to get it just right, and it would bug me forever to get it wrong.

 

Brightening out in the sun would certainly melt the case into a puddle out here in Arizona - at least for 9 months out of the year - so there's no way I'm going that route, although it's obviously worked well for some people.

 

I've had great luck brushing salon developer on the case and letting it sit indoors for a day or two, so I'll stick with that method until it fails me.  🙂

 

Leaving it alone is always a safe option, but having seen the results of getting it right, I personally would go for some type of de-yellowing process unless it looked like it'd be particularly risky for some reason.

 

Every case and every case owner is a special, unique snowflake. ❄️

 

I hear ya brudda! 

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Just as an example, here is the cart door and expansion bay cover from a case that arrived broken to pieces.  I've been "light brightening" them for 4 days now and took this picture so you can see the difference it has made.  They look pretty good, but still need at least another week with just sunlight.  Peroxide would speed things up pretty well.

 

 

a_sm.png

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How long does it typically take to brighten the case using just the sunlight method?  I have a 1200XL that has yellowing on the case, but the key cap lettering is yellowed too.  I've seen a couple videos on youtube where the key caps got ruined from the hydrogen peroxide streaking the key caps.  I'd like to brighten the system, but not use anything that would mottle the brown key caps or case sections.  I've put the entire computer out in bright sunlight and rotated the unit every couple hours (I also have to move it around because of trees on the property throwing shadows as the sun moves through the day) for the last day or two and I feel like the yellow is fading, just not very fast! 

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