Whitening yellowed plastic?  

I've always been pleased with the results
from using FLITZ plastic polish.

Novus Plastic Polish
That's the stuff I've used here in the US. Works really well.

yellowed plastic
Try one of those bathroom cleaners with bleach in it. I was cleaning off some ancient white plastic drapery cord tension thingees the other day which were extremely yellowed. I soaked them in a cup of the aforementioned cleaner (mixed with water) for about 10 minutes and was astounded at how well it worked. All the yellowing disappeared completely

I did order the novus polish...
I did order the novus polish today. I would be a bit worried about using bathroom cleaners as I would imagine that they are hard on plastics.
It's weird. I think the Stelton Jug must have been set in a window or something. It is very evenly yellowed. It is white though, as I can see white from a small scratch on the surface.

The housing of the
Stelton/Magnussen jug is made out of ABS (Acryl Butadien Styrene) Olive is going to kill me for this, but the very best way to remove the yellowing (most white colorants for plastics are titanium oxyde based) is to leave it for 24 hrs in water with 5-10% bleach. Do not attack it with any kind of polisher it will cause more dammage than good.

Hi Koen
I thought that any amount of bleach made white ABS more cream- was I misinformed ???

Can the glass part be removed...
Can the glass part be removed before I, (or if I was to submerge it in a bleach bath) soak it. It looks as if the innards can be snapped out. But I don't want to try this before asking.

By the way. I'm finding...
By the way. I'm finding this all very informative. Thank you all so much for your responses!
-Matt

Oh, i should mention that...
Oh, i should mention that when I said "bathroom cleaner with bleach in it" I didn't mean an abrasive like Comet or Ajax.
I meant those liquid spray bottle cleaners that you might use in your shower or something to bleach out mold in the grout. I think Clorox makes one, but there are others.

If you push...
in the two black knobs on the side the top will be pushed up by a spring in the bottom of the cylinder. Over the years there have beenmade different versions of the top. Some years ago I gave on DesignAddict a run down of those changes and the years they were made. It could be that your can is from a period in which the side nob action was re-enforced by a stainless steel spring. It just means that you have to push harder. There is a seal ring inside the black top but other than that there is no connection between the top and the glass. You can take out the glass and you will fid in the bottom either a stainlesss steel spring or a flat stainless steel part with a hole that matches the bottom cylinder of the glass liner. The flat piece is bend downward on both ends. You have to remove all of it before you give the ABS a good bath.

sorry...
I posted twice...

Thanks for the tip again! ...
Thanks for the tip again! The insides came out quite easily. I'll give it a bleach bath today and keep my fingers crossed.

Oven cleaner works wonders
oven cleaner works wonders just do not let it sit on the plastic for too long. It really works seems crazy I know.

Well... The bleach bath only...
Well... The bleach bath only lightened it slightly, very slightly. Boy, the person I bought this from must have let it set out in the sun for years!