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

I think I've discovered a new way of fixing yellowed plastic that doesn't involve hydrogen peroxide!

You know how controllers will often have sweat stains on them? I've never been able to remove this, save for a lot of rubbing with a magic eraser. I thought I might try soaking the plastic in Nappisan (a brand of laundry stain remover we have here) since, hey, that works for white clothes that have sweat stains. Imagine my surprise when I pulled the plastic out after a 48 hour soak to find it had also lightened the yellowing too!

Here's a PC Engine shell I did, the top half was soaked, the bottom was not:


That's the result of simply filling up the laundry tub with water, adding a cap of Napisan and leaving it to soak for 48 hours. No UV light, no hydrogen peroxide, nothing more.

Any clues what's going on here? Has anyone else ever tried this?

 

I would like to see it tested on something a little more yellowed

 

As far as I know the ultimate recipe is combining H2O2 plus some Oxi action like Napisan. Both work just fine on their own but combined they really do miracles.

 

That would be the next test! I have PS1 that's more yellowed, will see what it does to that. The camera's flash is lightening it from how it actually is though.

That's why I originally had Napisan, but this is far less work than Retr0brite.

*EDIT* Reading the label, it says it contains an "oxygen-based bleach". Retr0brite's key action is the large amount of oxygen it produces though a combination of hydrogen peroxide, UV light and an oxy action detergent, so it sounds like the Napisan alone is able to have similar effects. It can't be simply bleaching the plastic white since:
A) Napisan isn't a chlorine-based bleach
B) It's designed for use on color clothes, this would be a bad idea if it simply bleached things It's also had no effect on any colored parts of the console.

 

I found that a better way is to just soak whatever you want whitened in a clear container filled with 40 volume clear developer (which you can find at most beauty supply stores), and then leave it out in the sun for a while. I did this with my white PCE and it was whitened after just two hours.

 

Did you try just cleaning it normally?

I get dreamcasts that are a little off white, much like your bottom half and it just requires a clean.


Maybe wash the bottom part and compare?

 

Others have tried the sun method and resulted in uneven results, aka "blooming." The only permanent fix is to paint it with some kind of vinyl (usually marine) paint.

 

In fact, this process does involve hydrogen peroxide - if you look at the MSDS for Napisan the major ingredient is sodium percarbonate, which is an addition product of washing soda and hydrogen peroxide. It's reasonably stable in solid form, but as soon as you make a solution of it the H2O2 will start to decompose and release free oxygen. I would assume it's also got some sort of activator in it (possibly TAED), but this is not mentioned on the MSDS, probably because it's only being used in small quantities and is not considered to have any safety impact.

 

Only problem with that is, buying that much straight hydrogen peroxide (i.e not the creme that's most commonly available) would be insanely expensive in Australia.

Yep, I'd already washed both halves of the shell, with both soapy water, magic eraser and isopropyl alcohol before soaking the top half in Napisan. And as you can see, the top half, which received the soak, has come out much whiter.

I've had this problem a number of times when trying to use the sun, and I found a UV bulb doesn't cause blooming, provided you wrap up the item in cling wrap. Not the mention using the sun is a pain, since it moves around and goes away for 12 hours.

Really? That's even better, since I've found a cheap source of "liquid hydrogen peroxide" in that case.

 

Not if you are a hairdresser, 40vol isn't too hard to get if you know a hairdresser...

What about hydrochloric acid? or will that mess the plastic up?....

 

When you say "You can get 40% at a hairdresser in AU" are you referring to the creme stuff? That's the biggest, strongest bottle of hydrogen peroxide I've been able to find, since the only place I've been able to find the liquid stuff is at chemists, and they come in tiny bottles. So far, I like the results on this Napisan soak, provided it can keep this up and give me the same results as Retr0brite, I think this will become my favored way of de-yellowing. It takes a lot longer, but is it far less hassle and doesn't need a continual source of UV to work.

 

I would be very surprised if you could get 40% peroxide at a hairdresser - the strongest peroxide normally used for hair is "40 vol" - which is about 12%. Once you hit about 35%, it becomes significantly corrosive and will attack even healthy skin - I did manage to get some 40-50% peroxide from a paper making plant, but they required a fair amount of convincing that I was going to use it in a safe manner.

 

The Nappisan is the same Vanish?

 

There are 2 methods detailed out here by Heroic Decepticon:
http://heroicdecepticon.blogspot.com/2010/12/whitening-yellowed-transformers-toys.html

I haven't actually gotten around to doing anything like this myself.

 

Yeah I think people are mixing up the % vs. the Vol number. And as fireaza said, it normally comes as a creamy form, which makes applying difficult.

 

I'm not familiar with that brand, but I would assume any oxygen-based bleach that's designed for use on colors would be the same thing.

 

Where have you heard that? I didn't encounter anything like that, as long as you place everything evenly and make sure everything is submerged in the developer, you should be golden.

 

I encountered it a number of times, even when the solution didn't dry out. I put it down to the summer Australian sun being too hot and powerful, since I've never had the same problem using a UV bulb.