Partial yellowing?

[Amiga1992]

My A1200 has never been exposed to sunlight, and only one day had a severe exposure to nicotine.\

Could this be the reason why some of the keys in the keyboard are ywllowing, and others are not? It's very annoying. I got a mint machine and now some keys are yellowy ;(

But it was just one day! (though, in a club, first and last time I used my 1200 for VJing :P)

[Zetr0]

@Akira

the Yellowing as you know is the oxidization of the flame retardant chemicals added to the ABS plastic.

Some internal light source like florescent light will actually act as a catalysis for the this oxidization. as much of not more so than regular sunlight.

[Amiga1992]

So, why some rows are more yellow than the others?
The whole keyboard should be affected the same way
(and i dont remember using it under any sort of fluorescent light, i hate those!)

[StevenJGore]

On one of my A1200s, the '9' and '3' keys on the numerical keypad have yellowed quite badly, all other keys are as-new white. It must just be random.

Steve.

[mr_a500]

I've heard that a lot - that it's smoke and fluorescent light that causes it - but from my experience it's not that simple.

I had my A500 set up in a very smoky room beside a wood fireplace for 5 years and I've had it under fluorescent lights for at least 10 years - and it's still not yellowed at all. A Colour Computer 3 that I had carefully wrapped in a box in a closet for 15 years has ugly yellow patches and randomly yellow keys. An A4000 I just picked up (which was from a non-smoking bowling alley) has a perfectly white keyboard case, but half of the keys and spacebar are bright yellow. If the keys were exposed to the same conditions, why wouldn't they all be yellow and why not the case?

I picked up a couple free A500s recently and they're unbelievably yellow. They're as yellow as a banana - maybe even more yellow. Imagine a banana that was dipped in industrial yellow paint then thrown into a sewer and you've got the idea.

[Amiga1992]

So there's a mistery to solve here.
I want it solved with chemical formulaes and all
;D
It never happend to me for any other computer, that some keys would yellow while others don't. So I am puzzled by my 1200

[Yoto]

Hummm, interesting, my A1200 is 16 years old, its case is still white as snow and in its keyboard only the space bar is really yellow, and in the numpad lightly yellowed keys are number 9 and 3 too.So i guess its not random.

[alexh]

I heard it depends on which fingers you use for typing which you also use to scratch your arse.

If it's the index finger on your right hand then YUHNJK yellow first where if it is the index finger on your left hand then RTFGCV yellow first and if you use both hands or a different finger it varies...

[Yoto]

To: alexh

I heard it depends on which fingers you use for typing which you also use to scratch your arse.

You are right, now all came clear to me, i do use finger number 3 and finger number 9 to type and all the others to scratch my arse!

[Amiga1992]

loffle!

[mr_a500]

Well that explains why my A500 keyboard hasn't yellowed - I don't scratch my arse. However, my boxed CoCo 3 that went yellow must have been wrapped in the plastic wrap that I wiped my arse with. (...and the very yellowed A500 must have been entirely up someone's arse...)

[rkauer]

@Alexh:

ROTFLOLASTC!

Serious now: those random yellowing caps is a normal thing, I'm afraid.

Think with me: those keyboard are made from a batch, right? Do you people know how plastic injection is made?

Let me tell you.

You have the injector with the caps matrix, plus a funnel in the injector where the plastic (in pellet form), colour masterbatch (white, in Amiga case), fire retardant (also in pellet form), plus some "charge" (usually, plastic scraps). Those components are hand-mixed and tossed at the injector's funnel. Some of those pellets are heavier than others (specially white masterbatches). With the machine vibration, the heavier pellets go to the bottom of the funnel, leaving lighter ones on top.

As every injector operator knows, you need to add more auxiliars (add-ons) to the plastic formula to insure the final product have the minimal characteristics expected.

So, in face of those behaviours, they put some "surplus" of fire retardant in the mix, who (since it is lighter than other pellets) stays on top of the funnel more than in the bottom.

This results in some final pieces have more fire retardant than others, and even some without the product at all!

[StevenJGore]

We need to track down the injector operator that worked on the spacebar and the 3 & 9 numerical pad keys, and lynch him!

[Amiga1992]

I want the head of the one who worked in my row of yellowed keys.

OFF WITH THEIR HEADS!

[rkauer]

Originally Posted by Akira

I want the head of the one who worked in my row of yellowed keys.

OFF WITH THEIR HEADS!

Boy! That would be a massacre! From the time the Amiga cases and other plastic parts was made, that's the way the injection work.

Today we have more accurate processes (on-line mixers and dosers, etc) and raw materials. But this is today!

[alphonsus]

Originally Posted by alexh

I heard it depends on which fingers you use for typing which you also use to scratch your arse.

If it's the index finger on your right hand then YUHNJK yellow first where if it is the index finger on your left hand then RTFGCV yellow first and if you use both hands or a different finger it varies...

Eww, nasty!

[StevenJGore]

Just a thought that occurred to me last night... If our beloved machines (15+ years old) haven't started yellowing yet, can we assume that they won't ever yellow? Surely they'd have started by now? Are we lucky enough to have randomly got an Amiga without (or very little) fire retardant?

Steve.

[rkauer]

Originally Posted by StevenJGore

Just a thought that occurred to me last night... If our beloved machines (15+ years old) haven't started yellowing yet, can we assume that they won't ever yellow? Surely they'd have started by now? Are we lucky enough to have randomly got an Amiga without (or very little) fire retardant?

Steve.

That's the idea. From my point of view, fire retardant in keyboard and key caps are useful as giving a calculator to a monkey.

But don't count with "my Amiga still mint, it won't become yellow never". The more fire retardant, more of it will migrate to the surface. Even slight quantity of it will come to surface. It's a question of time. If your Amiga don't start yellowing in say 30 years, than you can say it won't become yellow...

[Yoto]

There is nothing we can do to avoid amiga cases from getting yellow, the truth is that the polymers that yellow the most probably had their stabilizing agents wrongly mixed.
The main yellowing agents are Ozone, UV radiation (either by direct sunlight or some lamps), humidity exposure, heat sources like gas or halogen heaters can sometimes act like a catalyst as well as some organic acids.Bad mixed polymers with stabilizing compounds will yellow earlyer than others, this is why some Cases and keyboards keys will turn yellow faster than others. We have to assume that Commodore had several plastic factories making cases and keys and some may had bad plastic mixtures, thus we dont know the proficency from most plastics used by Commodore, some may have been too many times recycled.

[CRAZG]

OK so, how do they burn?
The white ones burn better than yellow right? Anyone want to do a "scientific" experiment?