Cheap DIY retrobrite setup - no gels

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Cheap DIY retrobrite setup - no gels

Tools:

  • Walmart clear plastic tub of appropriate size for your item.  As clear as possible.
  • 12% hydrogen peroxide (I had about a gallon of 12%, and a gallon of 3%, had to dump them both all in the tub to fully cover the piece I was retrobriting.  So I reckon I have 7.5% hydrogen peroxide now?)
  • LED black light strip kit "32.8 ft LED Black Light Strip Kit 385-400nm https://www.amazon.com/dp/B07D7RKJYS?psc=1&ref=ppx_yo2ov_dt_b_product_details)
  • Masking tape
  • Clip-on stainless steel magnets (for clipping onto objects and forcing them to sink)

Instructions:  Tape the LED lights on all six sides of the box.  Spread them out as evenly as possible.  Pour the hydrogen peroxide in the tub.  Bubbles will make your object rise along with the apparently low density of hydrogen peroxide compared to the object (or maybe a chemist can explain why my stuff is floating).  Clip on something heavy to weigh the object down, but be sure the clip doesn't cover any area on the object you want to brighten.  Throw the stuff in the tub.  Check periodically to make sure your item isn't floating to the top.

Yes indeed, normal sunlight will work just fine.  This box helps spread the light more evenly around the object (sun can only come from one direction unless you install reflectors), and also I can run this box 24/7 instead of waiting for the few hours of sunlight we have in the north during the winter.

 

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Please note, the internet

Please note, the internet tutorials on retro-briting state that the yellowing will come back and more quickly the second time around.  You can apply protectorants to try to slow the yellowing process, but the protectorants need to keep being re-added.  Also to clarify, you have to dissassemble the computer and just put the plastic case in the tub, sorry you can't submerge the whole computer to my knowledge :-).  Before and after results are as below:

 

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There are many different

There are many different opinions on the internet regarding the yellowing phenomenon, its causes and remedies.

There is not even a commonly agreed mechanism for the color change. Some of the earlier tutorials blamed brominated flame retardants such as polybromine phenyl ethers, which supposedly are degraded by UV light to release bromine, which attaches to the plastic resin and turns it brown. But not all plastic exposed to UV turns yellow, and some plastic kept in sealed boxes indoors has turned yellow too. I am also not aware of any chemical analysis to verify the presence of a specific flame retardant in a yellowed plastic part. What is known is that ABS (the copolymer of Acrylonitrile, Butadiene, and Styrene) is almost always the plastic affected.

(For example, most of the keys on the IIc are shot in PBT, which does not yellow, but the space bar is ABS. This is typical in most keyboards because the space bar needs more toughness so it won't crack.)

As for the retr0brite process itself, there are nearly as many differing opinions. The same early tutorials called for a mixture of peroxide and TAED (tetraacetyl ethylenediamine) which will work differently from peroxide alone. Some have used peroxide and heat with no UV at all and reported good results. Some reported that yellow returned in less than a year; others have gone a decade without new yellowing. Some suggest the process irretrievably damages the plastic itself, exposing fresh resins that will quickly react with UV and oxygen in the air. Others find no change to the surfaces strength or texture, only a reduction of yellow tint.

Do you have access to a narrow-spectrum UV power meter to test the performance of the lights you are using and the %transmission through the bin?

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Excellent summary.  For those

Excellent summary.  For those who are purists, may be best to do nothing and leave the yellow there :-).  I do not have access to a power meter, so I'm not sure how much is getting lost through the plastic.  To that end I have no idea the luminosity or power of the lights themselves to begin with.  I also don't know how to estimate how long the tank and/or the hydrogen peroxide will last before it all needs to be replaced.  Not a lot of science here, for once I just said "eh, let's just try it".

I definitely did not have luck with the gel.  Lots of streaking and really couldn't figure out how to make it work out well.  Dunking it in liquid hydrogen peroxide seemed like a nice and lazy way to get even results.

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odingalt wrote:Excellent
odingalt wrote:

Excellent summary.  For those who are purists, may be best to do nothing and leave the yellow there :-).  I do not have access to a power meter, so I'm not sure how much is getting lost through the plastic.  To that end I have no idea the luminosity or power of the lights themselves to begin with.  I also don't know how to estimate how long the tank and/or the hydrogen

If you UV LEDs aren't hot to the touch they are low lumen, and given what you're using it's also safe to say the are low lumem.

 

I do have a question for anyone that may know... Original "white labeled" IIe keyboards, did they discolor in the same way that retrobrite will help?

 

I've got keys that have an orange tint and I'm not sure of their history and don't know if this is the same problem. Anyone know?

 

Hell, here's what they look like after a good cleaning:
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It's a valid method of

It's a valid method of retrobriting - the immersion method.

 

But for my money, the brush-on method with 6% - 12% liquid peroxide (20 volume or 40 volume or a mixture of the two) that has been thickened with xanthan gum and activated with a small amount of oxygenated laundry detergent booster (like "Resolve" powder) combined with sunshine and attention to detail always yields the best results.

 

By attention I mean re-brushing the thickened solution every 20 minutes and rotating the piece so that it receives even sun exposure.  Rebrushing keeps the solution from drying out and also distriubutes it evenly so that you adoid streaking.

 

Your method doesn't require supervision, but also doesn't always yield perfect streak-free results.

 

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My favorite retrobrite method

My favorite retrobrite method is the no chemicals, just direct sunlight approach. It works really well for keys, but most importantly it works for the infamous Apple IIe yellow spacebar. (What's up with that???)

 

This approach takes much more passive time, but much less active time. Here is the result of a controlled experiment I did for a total of 6 full clear days during the summer. It works in the winter too, but it takes longer since the outside temperature is also a factor. The before and after applies to the left allow key, the Enter is just for comparison and has been sun-brited previously:

 

 

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@CVT you're saying you just

@CVT you're saying you just put the keys out in the sun and the yellowing just disappears?

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Yes, but it has to be diret

Yes, but it has to be direct sunlight, not through a window. Good ol' UV from the sun!

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surprising

That's surprising as most commentators (including some professional conservators) point to UV light as the culprit in turning plastic (particularly ABS) yellow. But those keys look like PBT and not ABS.

 

baldrick: It's hard to locate products with bleach activator (TAED) in the US. From a patent search I saw that its function is to react with hydrogen peroxide to form peroxyacetic acid, a stronger bleaching agent which is effective at lower temperatures. So if it's not available an alternative approach is to use heat to ensure the bleaching reaction of the plastic resin can proceed.

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Not sure about the material,

Not sure about the material, but the sun only method also worked miracles for the spacebar of my Apple IIe. Here is the picture from the original eBay listing, and then after I cleaned it up and sunbrighted the spacebar for several days:

 

 

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thanks

Thanks, it definitely looks worth trying!

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possible alternative activator
robespierre wrote:

baldrick: It's hard to locate products with bleach activator (TAED) in the US. From a patent search I saw that its function is to react with hydrogen peroxide to form peroxyacetic acid, a stronger bleaching agent which is effective at lower temperatures.

It looks like tartaric acid is a possible alternative for the bleach activator. But it would have to be used in larger amounts to get the same effect.

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I am reasonably sure those

I am reasonably sure those LEDs aren't adding anything to the process, especially filtered through plastic. You are just using time and peroxide.

 

The sun adds heat and it's own mild bleaching effect which speeds it up.

 

 

 

 

 

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True. The transmission of

The transmission of light in polycarbonate really dips bellow 400 nm, if this is what this box is made of. However with so many LEDs and fairly thin walls, looks like enough makes is though.

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I have similar crates and I

I have similar crates and I am quite certain the plastic is not polycarbonate. The ones I have are labeled polypropylene.

I don't know the UVA absorption characteristics of PP (searches turned up only irrelevant articles) but it is rather sensitive to photodegradation from UV exposure, which should be kept in mind.

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