Is it UV rays that cause case and keycap yellowing?

[EscapeVelocity]

I was thinking that maybe using something like 303 Aerospace Protectant which has UV inhibitors for protection would help prevent yellowing.  Detailers use it on car dashboards and boats.

[Leslieann]

It's the UV protectant in the keys (specifically ABS) that causes yellowing, not UV itself.

[EscapeVelocity]

So blocking the UV before it hits the plastic would, in fact, help. 

[rm-rf]

just squirt some sunscreen on your caps if you are worried about it.

[Leslieann]

So blocking the UV before it hits the plastic would, in fact, help.

No, it can sit in a box and yellow.
The chemical that blocks UV rays causes the ABS to yellow over, it has nothing to do with light exposure.

[mogo]

This paper goes into ridiculous detail, but UV degradation is one way ABS plastics yellow. To summarize a section on "Types of Polymers Degradation"

• Chemical degradation
  Chemical degradation refers exclusively to processes, which are induced under the influence of chemical reagent (e.g. acids, bases, solvents reactive gases, etc.)
• Thermal degradation
  Thermal degradation refers to the case where the polymer, at elevated temperatures, starts to undergo chemical changes without the simultaneous involvement of another compound
• Biodegradation
  Biologically initiated degradation also is strongly related to chemical degradation as far as microbial attack is concerned. Microorganisms produce variety of enzymes which are capable of reaction with natural and synthetic polymers
• Radiolytic degradation
  When polymeric materials are subjected to high energy radiation (e.g. gamma radiation) changes are observed on their molecular structure, mainly chain scission, which leads to reduction in molar mass
  I severely doubt/hope that anyone's keyboard is not yellowed from radiolytic exposure 
• Mechanical degradation
  This generally, refers to macroscopic effects brought about under the influence of shear forces. These forces result in the formation of macro radicals [... which] can recombine in the absence of oxygen. In the presence of oxygen peroxy radicals may be formed, which leads to the degradation of polymeric chains
• Photodegradation
  Photodegradation is degradation of a photodegradable molecule caused by the absorption of photons, particularly those wavelengths found in sunlight, such as infrared radiation, visible light, and ultraviolet light. However, other forms of electromagnetic radiation can cause photodegradation.

In short, yes, UV light can yellow plastics. But, as in the common case of the NES/SNES, manufacturers add bromine to ABS plastic to act as a flame retardant which yellows over time regardless of exposure to light.

[EscapeVelocity]

This paper goes into ridiculous detail, but UV degradation is one way ABS plastics yellow. To summarize a section on "Types of Polymers Degradation"

• Chemical degradation
  Chemical degradation refers exclusively to processes, which are induced under the influence of chemical reagent (e.g. acids, bases, solvents reactive gases, etc.)
• Thermal degradation
  Thermal degradation refers to the case where the polymer, at elevated temperatures, starts to undergo chemical changes without the simultaneous involvement of another compound
• Biodegradation
  Biologically initiated degradation also is strongly related to chemical degradation as far as microbial attack is concerned. Microorganisms produce variety of enzymes which are capable of reaction with natural and synthetic polymers
• Radiolytic degradation
  When polymeric materials are subjected to high energy radiation (e.g. gamma radiation) changes are observed on their molecular structure, mainly chain scission, which leads to reduction in molar mass
  I severely doubt/hope that anyone's keyboard is not yellowed from radiolytic exposure 
• Mechanical degradation
  This generally, refers to macroscopic effects brought about under the influence of shear forces. These forces result in the formation of macro radicals [... which] can recombine in the absence of oxygen. In the presence of oxygen peroxy radicals may be formed, which leads to the degradation of polymeric chains
• Photodegradation
  Photodegradation is degradation of a photodegradable molecule caused by the absorption of photons, particularly those wavelengths found in sunlight, such as infrared radiation, visible light, and ultraviolet light. However, other forms of electromagnetic radiation can cause photodegradation.

In short, yes, UV light can yellow plastics. But, as in the common case of the NES/SNES, manufacturers add bromine to ABS plastic to act as a flame retardant which yellows over time regardless of exposure to light.

Thank you.

[EscapeVelocity]

So blocking the UV before it hits the plastic would, in fact, help.

No, it can sit in a box and yellow.
The chemical that blocks UV rays causes the ABS to yellow over, it has nothing to do with light exposure.

Thank you.

[Puddsy]

This paper goes into ridiculous detail, but UV degradation is one way ABS plastics yellow. To summarize a section on "Types of Polymers Degradation"

• Chemical degradation
  Chemical degradation refers exclusively to processes, which are induced under the influence of chemical reagent (e.g. acids, bases, solvents reactive gases, etc.)
• Thermal degradation
  Thermal degradation refers to the case where the polymer, at elevated temperatures, starts to undergo chemical changes without the simultaneous involvement of another compound
• Biodegradation
  Biologically initiated degradation also is strongly related to chemical degradation as far as microbial attack is concerned. Microorganisms produce variety of enzymes which are capable of reaction with natural and synthetic polymers
• Radiolytic degradation
  When polymeric materials are subjected to high energy radiation (e.g. gamma radiation) changes are observed on their molecular structure, mainly chain scission, which leads to reduction in molar mass
  I severely doubt/hope that anyone's keyboard is not yellowed from radiolytic exposure 
• Mechanical degradation
  This generally, refers to macroscopic effects brought about under the influence of shear forces. These forces result in the formation of macro radicals [... which] can recombine in the absence of oxygen. In the presence of oxygen peroxy radicals may be formed, which leads to the degradation of polymeric chains
• Photodegradation
  Photodegradation is degradation of a photodegradable molecule caused by the absorption of photons, particularly those wavelengths found in sunlight, such as infrared radiation, visible light, and ultraviolet light. However, other forms of electromagnetic radiation can cause photodegradation.

In short, yes, UV light can yellow plastics. But, as in the common case of the NES/SNES, manufacturers add bromine to ABS plastic to act as a flame retardant which yellows over time regardless of exposure to light.

This is the most in depth I've seen someone go into this, thanks for the informative post

[UsualSuspectXXX]

This paper goes into ridiculous detail, but UV degradation is one way ABS plastics yellow. To summarize a section on "Types of Polymers Degradation"

• Chemical degradation
  Chemical degradation refers exclusively to processes, which are induced under the influence of chemical reagent (e.g. acids, bases, solvents reactive gases, etc.)
• Thermal degradation
  Thermal degradation refers to the case where the polymer, at elevated temperatures, starts to undergo chemical changes without the simultaneous involvement of another compound
• Biodegradation
  Biologically initiated degradation also is strongly related to chemical degradation as far as microbial attack is concerned. Microorganisms produce variety of enzymes which are capable of reaction with natural and synthetic polymers
• Radiolytic degradation
  When polymeric materials are subjected to high energy radiation (e.g. gamma radiation) changes are observed on their molecular structure, mainly chain scission, which leads to reduction in molar mass
  I severely doubt/hope that anyone's keyboard is not yellowed from radiolytic exposure 
• Mechanical degradation
  This generally, refers to macroscopic effects brought about under the influence of shear forces. These forces result in the formation of macro radicals [... which] can recombine in the absence of oxygen. In the presence of oxygen peroxy radicals may be formed, which leads to the degradation of polymeric chains
• Photodegradation
  Photodegradation is degradation of a photodegradable molecule caused by the absorption of photons, particularly those wavelengths found in sunlight, such as infrared radiation, visible light, and ultraviolet light. However, other forms of electromagnetic radiation can cause photodegradation.

In short, yes, UV light can yellow plastics. But, as in the common case of the NES/SNES, manufacturers add bromine to ABS plastic to act as a flame retardant which yellows over time regardless of exposure to light.

Wow, so much detail in that article. I'll have to read through the entire thing when I have some more time. Thanks for posting it.

[atarione]

maybe I missed a memo or something but internet "hacks" for making old yellowed plastics white / beige again have been online for ~15yrs at least..

blah blah blah something like this::

http://www.retrofixes.com/2013/10/how-to-clean-whiten-yellowed-plastics.html


so sort of who cares?? also I have black keyboard so really who cares =p

[WhateverZYX]

It's the UV protectant in the keys (specifically ABS) that causes yellowing, not UV itself.

Specifically for ABS, it's also the polymer itself which yellows after the UV-Absorber is used up.

To quote a paper (found on http://www.irbnet.de/daten/iconda/CIB9937.pdf): 
"Photo-product species formed by photo-oxidation of the PB
phase are strongly dependent on irradiation wavelength (Jouan and Gardette 1992). Photo-oxidative degradation of the
polystyrene component of the styrene-acrylonitrile (SAN) copolymer also yields chromophores (Davis and Sims 1983, Jouan
and Gardette 1992). Kulich and Gaggar conclude that initial colour fading is due to oxdation in the SAN phase, and subsequent
yellowing discolouration is due to oxidation of the PB phase (Kulich and Gaggar, 1996)."

The best protection against yellowing of a polymer would be using HALS-Additives (https://en.wikipedia.org/wiki/Hindered_amine_light_stabilizers), which continuously absorb free radicals, or a surface coating.

[tp4tissue]

Same Reason why Tp4 Never goes Outside..

Already too yellow as a sifo..

[chyros]

In short, yes, UV light can yellow plastics. But, as in the common case of the NES/SNES, manufacturers add bromine to ABS plastic to act as a flame retardant which yellows over time regardless of exposure to light.

This is observably false. Why are all my NIB keyboards pristine white then? Also, bromine is famously a dark brown liquid, which might make it easy for people to believe that it's in there, but bromine is NOT used as a fire retardant - it regards several bromine-based compounds which are a completely different kettle of fish. Saying manufacturers add bromine to ABS is more or less equivalent to referring to water as "hydrogen" or to air as "helium".

Glancing through this there is not a word about bromine anyway so I'm curious what the supposed mechanism behind the apparently spontaneous decomposition behind this "bromine" is supposed to be if not through photooxidation.

[Deefenestrate]

This is why I only buy organic pasture fed keyboards.

[mogo]

In short, yes, UV light can yellow plastics. But, as in the common case of the NES/SNES, manufacturers add bromine to ABS plastic to act as a flame retardant which yellows over time regardless of exposure to light.

This is observably false. Why are all my NIB keyboards pristine white then? Also, bromine is famously a dark brown liquid, which might make it easy for people to believe that it's in there, but bromine is NOT used as a fire retardant - it regards several bromine-based compounds which are a completely different kettle of fish. Saying manufacturers add bromine to ABS is more or less equivalent to referring to water as "hydrogen" or to air as "helium".

Glancing through this there is not a word about bromine anyway so I'm curious what the supposed mechanism behind the apparently spontaneous decomposition behind this "bromine" is supposed to be if not through photooxidation.

I never meant to say that all plastics have brominated flame retardant incorporated. I was merely speaking off-hand about why some plastics may yellow over time. I remember reading this article in which someone from Nintendo* states that heat light OR heat generated by the device can cause yellowing in the brominated plastic. The article-writer states that it can happen by virtue of being just exposed to oxygen itself, though I don't take this as a credible scientific source, he could be correct. I apologize if I was misleading, but I do not believe I spoke any misinformation.

*I could not find evidence as to what position Casey Ludwig occupies at Nintendo, they're just quoted often about this yellowing plastic response.

[Leslieann]

maybe I missed a memo or something but internet "hacks" for making old yellowed plastics white / beige again have been online for ~15yrs at least..

blah blah blah something like this::

http://www.retrofixes.com/2013/10/how-to-clean-whiten-yellowed-plastics.html

kind of...
It's better than nothing, but it's a short term fix and done repeatedly will actually degrade the plastic. It will yellow again, and faster than it did the first time.

There is no permanent fix.

[EscapeVelocity]

In short, yes, UV light can yellow plastics. But, as in the common case of the NES/SNES, manufacturers add bromine to ABS plastic to act as a flame retardant which yellows over time regardless of exposure to light.

This is observably false. Why are all my NIB keyboards pristine white then? Also, bromine is famously a dark brown liquid, which might make it easy for people to believe that it's in there, but bromine is NOT used as a fire retardant - it regards several bromine-based compounds which are a completely different kettle of fish. Saying manufacturers add bromine to ABS is more or less equivalent to referring to water as "hydrogen" or to air as "helium".

Glancing through this there is not a word about bromine anyway so I'm curious what the supposed mechanism behind the apparently spontaneous decomposition behind this "bromine" is supposed to be if not through photooxidation.

This is my experience too.  New in box is almost never yellowed.

[rich1051414]

Using sunscreen may in fact make it worse. I have old keyboards that have brown marks where the palms rested, presumably, from lotion. There are many things that can brown/yellow plastic. I have also heard of keyboards pulled from hot attics that have turned a brown color over time.

[Leslieann]

Just because what you have witnessed has stayed nice inside a box doesn't equate to all.

There is more than one way to make ABS and mandated additives and the chemical makeup of those chemicals have changed over the years. It also depends on where a product was made as to how the ABS was formulated. Some used fire retardants (required by some countries), which in some cases was Bromine, higher end items used UV protectors while cheaper ones did not. So don't go by the idea that "well mine did X" because a year difference in manufacturing (law change), or where it was made or even who it was sold to can make a big difference.

Years ago it was noted that Walmart was selling the same toys as ToysRUs, however the Walmart toys were rotting in the sun. It was later found that Walmart was having special batches made without the UV protection in order to save a few dollars. Same look, same part number, the only difference was where you bought it.

[Daniel Beardsmore]

I confirmed with Signature Plastics that Comptec keycaps were all ABS. Yet, the old Comptec ABS keycaps were very hardy, and held their surface texture well. Has anyone ever seen Comptec keycaps (or any other brand of quality double-shot) anywhere near as bad as modern ABS keycaps go in a short space of time? (I can't speak for new SP keycaps personally.)

Tai-Hao suggested to me that the change from thick ink screen printing (not pad printing) to coated screen printing of keycaps was due to RoHS legislation that left them with a thinner ink that could no longer be used without a protective coating. This isn't independently verified, but I have to wonder if RoHS or other legislation no longer allows people to make ABS as wear-resistant as it was, or at least, not at the same price! (i.e. to do it properly you'd have to pay more) Maybe it's not RoHS, maybe it really is a cost saving in ABS formulation. Signature Plastics didn't offer any more detailed insight into what may have changed or why.

In any case, light is definitely a trigger for the yellowing process, regardless of what happens from that point on.

As for product grade, I have a NIB, non-yellowed keyboard that was incredibly cheap and nasty (OK-100M) so you could indeed get rubbish keyboards that didn't yellow in the box.

[chyros]

I confirmed with Signature Plastics that Comptec keycaps were all ABS. Yet, the old Comptec ABS keycaps were very hardy, and held their surface texture well. Has anyone ever seen Comptec keycaps (or any other brand of quality double-shot) anywhere near as bad as modern ABS keycaps go in a short space of time? (I can't speak for new SP keycaps personally.)

I've plenty of Comptec caps, and they all have very strong texture, as you said. I think they came with a much coarser texture than other caps out of the box anyway though, so that's probably it. Also, the switches they were on were so extremely awful that I don't imagine anyone would've considered typing on them for long enough to wear them out xD . Reminds me a bit of Stackpole's capsl actually, in that regard.

Modern SA caps have virtually no texture to begin with so losing it isn't really a thing xD .

[Daniel Beardsmore]

Well, Comptec keycaps were used with Cherry MX, Futaba MR and ML, Hi-Tek High Profile and various others, so I'm sure they were used with something that you don't hate.

I'm not convinced that modern ABS would hold up like old ABS — the BBC Micro for example typically used Futaba MR switches and Comptec keycaps, and I've never seen one with keycaps worn out like what you see with ABS.

The question then is, do gloss Comptec keycaps get the cellulite look that modern ABS does after use?

[EscapeVelocity]

Im gonna use Aerospace 303 Protectant.  It doesnt leave a greasy film nor a gloss finish. 

Just for my peace of mind.  Cant hurt.

[Blaise170]

I had a new in box AEK II that was still pure white - so there are definitely reasons besides chemical changes.

[Leslieann]

ABS is a generic label for any plastic using a primary combination of scrylonitrile butadiene and styrene, the amount of each of those can vary by as much as 35% and that doesn't include what else is tossed into the mix. Most importantly in this case though is stryrene, which is well known for yellowing due to pretty much anything you can imagine, from heat, to light, to additives and more, even just good old oxygen. It yellows over time, period.

The best way to remove it tends to almost always be the same, which has already been mentioned, just be aware that yes, it may be adding to the degradation of and mostly likely removing some of the plastic.

There are quite a few good places to research this, Wikipedia even mentions the problem on the ABS page and on the styrene page. This is also a far more in depth article if you want to spend the time on it, though the initial abstract summary is probably enough to give you the idea that it will yellow and there is little you can do to stop it unless it was baked into the plastic when it was made.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4320144/