Removing "Yellowing" From Beige Case Plastics

[Topcat]

I've been trying experiments with some 'household remedy' chemical yellowing removal, and after a few tries, I found a winner!!

Before:



After:



More to come as I refine this process.

[keeney123]

That worked good.

[goontron]

Ive been on this trail too. Old vintage Mac keyboards and Model M/F PC boards
What is your current process?

[kc8adu]

https://en.wikipedia.org/wiki/Retr0bright

[Topcat]

Knew all about retrobrite....the home remedies are the same thing for pennies. Oxy-based cleaners.

[junktv]

TSP (trisodium phosphate) and dawn or any household cleaner spray works ok. Always alcohol but it can be hard on the painted stuff.

[kc8adu]

this is not nicotine build up.
its yellowing from bromine based flame retardant.

[junktv]

My bad I was just speaking from experience.

[Topcat]

I think I've found my happy place!! I tested it on the worst case I had, came out looking new!!

Before:







In progress, in my super duper bromine yellowing reversing soup...



some other whatnots added with this batch.


After:







I'll post up the ingredients soon. I don't have proportion measurements yet, as its still kind of experimental....but I have the ingredients narrowed down after a few weeks of experimenting...

[diif]

Nice work I wonder if the ingredients will be available in the uk ?

[Topcat]

Originally Posted by diif

Nice work I wonder if the ingredients will be available in the uk ?

It's all grocery store items, nothing crazy, illegal, or hard to find.

[diif]

Originally Posted by Topcat

It's all grocery store items, nothing crazy, illegal, or hard to find.

Cool, I look forward to the recipe.

[Topcat]

Ok, time to let the cat out of the bag. Here's the key ingredients:

1) Oxy-based detergent
2) Hydrogen Peroxide
3) Water
4) Intense UV source (sunlight can't be beat)



I've tried quite a few oxy-based cleaners, this was the best one. This one (unlike most) doesn't foam up. If there's a layer of foam floating on the surface, it blocks the sunlight. Strong UV is the catalyst that makes the whole process work. The hydrogen peroxide is introduced to speed up the process. The process works without the peroxide, but it takes a long time and will require a few treatments if its really yellowed. The 'soup' loses its potency after about 5~6 hours, and 6 hours in direct sunlight with this combination will do the trick. This nasty yellow enlight case was restored after just one 6hr treatment. Other similar yellowed items took 3 to 4 treatments without the peroxide, so its definitely a key ingredient.

Unlike 'retr0brite', which is more of a paste, and has to be reapplied when it runs off or dries out in the sun, the 'soup' works far better....and costs almost nothing. You just have to keep things submerged, which is why the rocks are there. You just have to shift them around periodically so to not get shadowing. Around 5~6 hours, you will notice its not bubbling/fizzing anymore, that's when you know the magic is all gone, and its time to remove & rinse off.

Ok, so the process is pretty simple. Mix the detergent with warm water in a pan and then add the peroxide, then place your items in the mixture yellowed side up. Then place it in direct sunlight for 6 hours. You may need to place heavy objects on the items to keep them submerged. If you do, be sure to rotate the heavy objects every so often so to not get shadows. That's basically all.

I am still working on proportions, I don't have measurements per gallon of water ratios yet....its like my spaghetti sauce, I add until it 'feels right'...but use generous portions of the detergent & peroxide.

The final pics of the yucky enlight case after I cleaned up the rest of it:





Nice home for a VP6



Where did this come from?



That's all for now...

[Topcat]

The case of the left....

Before:



After:





I love it when a plan comes together!

[junktv]

Seems like we need a paper mache volcano for this.

[stj]

so it's Hydrogen-Peroxide and Baking Soda ?

[Topcat]

Originally Posted by stj

so it's Hydrogen-Peroxide and Baking Soda ?

its not sodium bicarbonate (baking soda), its sodium carbonate (aka soda ash)....which is the key in oxy-based cleaners.

[eccerr0r]

The need for UV is weird, as I thought it was the UV that caused the damage to begin with?
How about using a blacklight? Or does it need to be of the germicidal type?

What happens if you simply heat the solution instead of using UV light?

[Topcat]

Originally Posted by eccerr0r

The need for UV is weird, as I thought it was the UV that caused the damage to begin with?
How about using a blacklight? Or does it need to be of the germicidal type?

What happens if you simply heat the solution instead of using UV light?

The UV is the catalyst, so I understand from the people that know more about chemistry than me. Without the UV, the above described formula is useless. Blacklight did nothing. I did try a 400W metal halide 'grow light', that worked, but was slow going. the UV has to be extremely intense, sunlight is best. Ironic that yes, UV caused the yellowing (bromine offgassing) in the first place....and UV with the 'soup' will undo the damage.

[stj]

i wonder if a sunbed would work?
that or - on a smaller scale, a germicidal tube from my eprom eraser.