I think I discovered a new way to de-yellow plastic!

That sounds likely! Would require some form of continual heating, perhaps an aquarium heater? Seems to work pretty well when cold, but heating it up would probably speed up the process.

I've also been playing with the idea of if it's best to regularly empty the old Napisan and make a fresh batch or not. Weirdly enough, the opposite seems to be true. After I saw the impressive results with the top half of the PC Engine shell, I decided to pop the bottom half in along with it. I'd been changing the solution every 24 hours, but the bottom half didn't seem to become as white as quickly as the top half, which was left to soak in the same solution for 48 hours. So I left the bottom half in for 48 hours and now it's the same shade of white as the top. Also seems to be slowly removing the sweat stains, but man, these are some stubborn stains!

 

Last year I tried soaking for four days a badly yellowed computer case in water saturated with Oxy CLean.
It did not do any miracle. It got a little better maybe but it was still plenty yellow. But then there might be something more to Nappisan. Have you tried it with something really badly yellow ? And please clean it normally before. I did clean the computer case before I put it in the Oxy.

 

Once I finish experimenting with this PC Engine, I've got a much more yellowed PC Engine (can never have enough PC Engines!) that would be a good candidate. It's been close to a week since I started this, so it seems this technique needs more time to work, so in your case you didn't leave it in for long enough, or as you said, there might be an extra ingredient in Napisan. I also suspect that keeping the item in a smaller, more concentrated volume (like putting it in a small container) would probably be more effective than putting it in a big laundry tub like I have now.

 

Okay, I've taken the parts out of the bath, since they've had a pretty good long soak and it doesn't seem like they're going to get any whiter. They came out quite white! But I wondered what would happen if I followed it up with a treatment of Retr0brite? The answer? It brings it to the finish line!


(part on the left has only had the Napisan soak, part on the right has had that plus 24 hours Retr0brite treatment)

Don't be fooled, the lighting makes them look yellow-ish, but in person, they look much whiter. As you can see, there's not a huge difference, but the one that's had the Retr0brite treatment is a little whiter.

It seems to me like the winning formula is to give the parts a soak in Napisan to get rid of most of the yellowing, followed by a treatment of Retr0brite to finish up. I'm in the process of doing a PC Engine shell (just need to finish Retr0briting them) so I'll be able to compare this new method to a traditional Retr0brite treatment, as I have another PC Engine that I'd Retr0brited a few months back.

 

Who here likes comparison photos?

PC Engine that had just a Retr0brite treatment on the left, PC Engine that had both Retr0bright and a soak in Napisan on the right. Again, colors in the photo are not accurate, the console on the right is really white, don't think it can get any better. For some reason, the bottom half of the console doesn't looks as white, which is odd since they had the same treatment for the same length of time. It also didn't turn as white after just the Napisan soak either, so that might just be how it is.

 

Great effect actually, it's a shame that it didn't work the same for the bottom of the case. Anyway, it's better now than it was before and that's the main thing.

 

Oh, it worked for the bottom of the shell, it's just not quite the same shade of white as the top. I figure that plastic itself must be different from the top (maybe from a different batch?)

 

Yes. In the UK it's called Vanish Oxy Action or something.

http://www.vanish.co.uk/products

Just different names for different territories.

 

That sure looks like Napisan. Different packaging though, the powder I use comes in a tall cylinder.

 

Yeah we get that stuff, it's an additive you can stick in the washing machine. Again don't remember the name.

Problem is here in the UK it's likely the vital ingredient is missing due to how strict our product regulations are.

 

The forumulation is different, but the main components seem to be the same - and they both have sodium percarbonate in them (that "sodium carbonate compound with hydrogen peroxide" in the AU MSDS is the same thing with a rather more opaque name).


Napisan Oxi Action (AU):

http://www.rb-msds.com.au/uploadedFiles/pdf/Napisan (Vanish) OxiAction-v17-31448.pdf

Vanish Oxi Action (UK)

http://www.litelines.co.uk/downloads/RC0615.pdf

 

How on Earth did you find that information? Are you a wizard/chemist?

Today I needed to grind some of the plastic away from the PC Engine shell I did with the new treatment. The color of the plastic on the inside of the cut is the same as the outside that was de-yellowed! I think this makes it clear that I've been able to bring it back perfectly to it's original color! The final test will be:
A) Does it work as well for more heavily yellowed items?
B) Does it work for non-white plastic?

 

How about this for a test subject:

http://www.ebay.co.uk/itm/WOW-Sega-...1022505098?pt=Video_Games&hash=item4d127a948a

 

Not even sure Billy Mays could whiten that!

 

Sweet merciful Cthulhu! Well, assuming it's not the kind of yellowing caused by to exposure to air (did the Saturn ever suffer from that?) it might work. I've got two more consoles in mind to continue testing this new method, right after I finish de-yellowing the rest of my PC Engine setup.

Also, to give you guys a more accurate idea of how well this worked, you know how Hu Cards never yellow? Well...

Whiter than a KKK member's Sunday best robes!

 

I'm sort of a chemist - in any event, that's what my degree is in, even if I've never actually worked in the field, and luckily although it was a rather long time ago I have a good memory. It's not hard to find that sort of information for most commercial products - just search for the product name + "MSDS" - the level of detail varies depending on which country it's being prepared for, since some places have different thresholds for what has to be described. They will generally at the least tell you what the major ingredients are, though.

 

I wouldn't even know what MSDS stands for, let alone what each of the ingredients do

 

I recall that it stands for "Material Safety Data Sheet" its also used for guidelines about other types of safety. Such as in IT if someone gets shocked enough to were it causes burns then they may refer to a MSDS, or for a chemical burn etc. I remember at a CTC I went to a few years ago that all the classes had a MSDS for any type of incident, I think its also a Standard Operating Procedure too. Never hurts to be prepared lol

HaloSlayer255

 

Ah, that's what it means eh? Thanks!

I think ASSEMbler might be on to something with his suggestion of using the sun to speed up the process. I've noticed that the sun streams though the window in the bathroom of a morning and shines on part of the laundry tub. I compared the plastic piece that was in the sun with the one that was in the shade and the one in the sun was a little whiter. Putting the pieces under UV might indeed speed things up, it's something I think I'll try once I start experimenting with this a little more. Unlike Retr0brite though, UV isn't essential to the process, as the plastic you can see in the above photo was upside down the entire time (it wouldn't sink otherwise!) and never saw the sun.