Retr0Brite and Zenith ZKB-2

[engicoder]

Over a year ago I acquired a Zenith ZKB-2 with green alps from a friend in exchange for a helping him set up his new computer. See this thread.

It seems that many of these green Alps endowed Zenith's end their lives as donor boards once a GH member gets ahold of them. Part of me is leaning that way. The other half is a bit charmed by this keyboard and its internal speaker chirping away as you type. While my subconscious battles over its final fate, I decided I would have at it with some Retr0Brite and see what happens. If the results are bad, its a donor...if there good, the decision remains difficult.

The Process

I decided to go with a liquid approach instead of paste/gel. H₂O₂ is relatively cheap and the case is thin, so submerging it in liquid shouldn't be too difficult. I went to Sally and picked up some developer for about $10. I already had some oxy clean at home. I got a gallon on 20 volume and a liter of 40 volume which combined yield about a 7% solution, which is a little lower than recommended, but should work.



I have a UV exposure unit I built previously to expose photosensitive PCB material. I put the retr0brite in a plastic container in the bathtub ( in case of disaster ) and then placed the UV above.



The case took about 5 hours. When it was finished, I put the key caps in the remaining solution. The keycaps sink when turned over. I placed the container on some boxes and put the underneath.



The key caps to much longer, but the solution had probably lost strength due to the breakdown of the H₂O₂.

Results

The Case:

Here are some photos of the case before. The inside color is probably the original color. Note the build markings with a date of 87-09-23. Who knew Borg Warner made keyboard cases?


After


Its still slightly yellowed, but close to original.

The Key Caps

Before


After


Issues:

There results weren't perfect.
The Zenith logo on the dip switch cover was silver originally. The Retr0Brite removed the silver color. I can paint it back. Curiously, the silver on the "data systems" remained.



The white key caps still show some yellowing, while some of the grey key caps suffer from some white bloom; noteably the "+" key on the numpad.



Doing it again, I would do the different color keys as separate batches and use fresh solution for each.

Conclusion:

Overall, I happy with the results. Its not perfect, but its much better than it was. Will it become a donor board? Not right now, but should I find I really need (want) to build a green Alps board....well, maybe
 

[intelli78]

Really impressive! I have some boards and keycaps that could really use this treatment... just a matter of tracking down the right chemicals. This process is really impressive, the FAQ about its history is a pretty interesting read.

[engicoder]

Really impressive! I have some boards and keycaps that could really use this treatment... just a matter of tracking down the right chemicals.

I got the peroxide from Sally Beauty supplies. They have stores just about everywhere.

[terrpn]

looks nice...........

great job and one of my favorite boards and switches

.....i left the speaker on

you are more hi tech than me...........i just let mine cook in the sun

[False_Dmitry_II]

Looks good. That's one of those switches that I'd like to try for a week, but I generally prefer clicky over linear.

It's also cool that you got the guy back on The One True Keyboard when he was using something bad.

you are more hi tech than me...........i just let mine cook in the sun

How would that work? The sun is what caused the problem in the first place.

[Vanilla]

Wow that's impressive! I've heard of this from people doing a similar thing to yellowing super nintendo case housings.

But I've also heard that the process is not permanent as further UV exposure, after the fact, will cause it to yellow once more as it's the plastic's formulation that makes it yellow in the first place and you will need to repeat the process once more to bring back its original luster.

[jacobolus]

How would that work? The sun is what caused the problem in the first place.

The original reaction happens with UV exposure over a period of years.

However, if the keycaps are in a hydrogen peroxide bath, then a few hours of UV exposure reverses the original yellowing reaction.

You can read about the chemistry at http://retr0bright.wikispaces.com

[engicoder]

But I've also heard that the process is not permanent as further UV exposure, after the fact, will cause it to yellow once more as it's the plastic's formulation that makes it yellow in the first place and you will need to repeat the process once more to bring back its original luster.

That's true, it could yellow again with time...a lot of time. This could possibly be prevented to some degree by applying a clear sealer after its been restored (or before it yellows)....although, I'm not sure the efficacy of this technique has ever been validated.

[False_Dmitry_II]

How would that work? The sun is what caused the problem in the first place.

The original reaction happens with UV exposure over a period of years.

However, if the keycaps are in a hydrogen peroxide bath, then a few hours of UV exposure reverses the original yellowing reaction.

You can read about the chemistry at http://retr0bright.wikispaces.com

His post makes it sound like he just sticks the stuff outside and the sun somehow makes the yellow go away.

I know the chemistry involved with peroxide. For the record, it's with any light, not just UV. UV is just higher powered.

[Vanilla]

But I've also heard that the process is not permanent as further UV exposure, after the fact, will cause it to yellow once more as it's the plastic's formulation that makes it yellow in the first place and you will need to repeat the process once more to bring back its original luster.

That's true, it could yellow again with time...a lot of time. This could possibly be prevented to some degree by applying a clear sealer after its been restored (or before it yellows)....although, I'm not sure the efficacy of this technique has ever been validated.

True. Re-yellowation is especially slowed if the board is kept away from the sun too.
Not so sure about sealing it as you might be screwing yourself over if it yellows once more and the yellow is now sealed in. XD
Then again perhaps if you sealed every nook and crevice including the underside.

[paicrai]

noice

[koalapear]

What a transformation! Looks fantastic!

[engicoder]

True. Re-yellowation is especially slowed if the board is kept away from the sun too.
Not so sure about sealing it as you might be screwing yourself over if it yellows once more and the yellow is now sealed in. XD
Then again perhaps if you sealed every nook and crevice including the underside.

Your right, I'm sure the sealer would make it more difficult, if not impossible for the retr0brite to get at the plastic. I think its easier to just see what happens and if need be, repeat the process.

[terrpn]

How would that work? The sun is what caused the problem in the first place.

The original reaction happens with UV exposure over a period of years.

However, if the keycaps are in a hydrogen peroxide bath, then a few hours of UV exposure reverses the original yellowing reaction.

You can read about the chemistry at http://retr0bright.wikispaces.com

His post makes it sound like he just sticks the stuff outside and the sun somehow makes the yellow go away.

I know the chemistry involved with peroxide. For the record, it's with any light, not just UV. UV is just higher powered.

a bath of oxy clean, hydrogen peroxide, strong sunlight (UV) for a couple hours= white

[davkol]

Retrobright: The Yellow Strikes Back

[ClarusWorks]

Also, I suspect that Borg-Warner made the plastic resin used to mold the case, not the case itself.  Looks like they used to make plastic but sold that business to GE:  http://www.nytimes.com/1988/06/17/business/company-news-borg-warner-to-sell-chemical-unit-to-ge.html

I suspect that the "Fei Horng" molded into the case was the actual manufacturer, IIRC a lot of Zenith keyboards were made in Taiwan.