Removing yellowing from Amigas with peroxide - Page 5

Photon · 16 July 2008, 00:10

Might just go and paint my whole A600 matte black to match the TFT... I know where all the keys are anyway 8)

Any suggestions as to what paint to get that gives good results on plastic?

Yoto · 16 July 2008, 01:52

I wanted to make something radical to my 1200, maybe to wrap the top case in decalcs from game title covers or amiga magazine covers,(using inkjet transfer paper,and some transparent varnish to cover it all), and for the bottom case, i could just paint it in metalized dark grey, or i could just paint it all in metallic dark grey, carshops usually do those paint jobs quite well...although a bit expensive too...

chiark · 16 July 2008, 15:44

Well, I went to try and buy some.

Boots stock 6%. Sainsburys have 3%.

Worryingly, a google search for hydrogen peroxide had a sponsored link from the British Police saying "Suspicious? REPORT IT!"... I can't help but feel that asking for 20-30% H2O2 is drawing attention, even in the small volume I want to bleach the 4000 front back to minty freshness!

Yoto · 16 July 2008, 16:03

Really! Here in my country the old ladies buy 60% H2O2 and put 3 single drops in their tea!They are not very smart but at least they make it to the 100 years old...LOL

Merlin · 16 July 2008, 16:41

@ Chiark

If you really need some, I'm not too far away from you, perhaps we could arrange a meet somewhere between us, as long as MI5 aren't watching LOL

Yoto · 16 July 2008, 16:58

And you could Codename it: 7UP

Magno Boots · 17 July 2008, 01:50

@ Chiark

I couldn't obtain anything stringer than 6% either but don't worry as this works fine. Just a little more time is required.

Two 6% bottles from tesco left in a jar for five days in the sun produced fantastic results.

Infact the keys turned out brighter than the case I have just painted (white primer only with lacquer finish).

This 600 was actually banana coloured one week ago... really.. no kidding, it was close to being binned.

The grey keys were only in for one day and need another blast.

See current picture..

Attachment 17174

BTW has anyone got a spare Z key as mine has gone walkies?

Good luck guys.

Zetr0 · 17 July 2008, 01:54

@Magno

Looks fantastic m8

PM me you deets my friend and a 'Z' will be in the post

rkauer · 17 July 2008, 05:15

@Magno: You painted the badge? Mine have the C= logo metallic!

chiark · 17 July 2008, 10:52

@Magno,
Excellent result! I'll go and get the 6% then. The only thing I'm confused about is this thing called "sun" - what's that? I live in the North

@Merlin
Thanks for the offer - I'll try the 6%

@Yotoxionomai
I've found 35% available online classed as "food grade" - bloody weird. I might order some...

I'll try the face of a 4000 in the 6% stuff... Tempted to mask a bit off, but I know that if I do that I'll never get it to be the same as the other bits!

Yoto · 17 July 2008, 12:09

The process involved in reversing the yellowing is very impressive, i wonder...since rich oxigen reverses the process, then the plastic yellowing agent should be related to carbon dioxide, rather than UV or acid compounds.
In another approach, CO2 turns water a bit acid, known as carbonic acid, (like the humidity in our fingers and in air), and that may well be why some amiga plastic parts react to CO2 in its acid form or H2CO3 so H2O2 seems to somehow neutralize and reverse it.
Well, the CO2 above statements are wrong, H2O2 creates a process that releases the O2 in plastic...how i´m not sure...

zipper · 17 July 2008, 12:34

What about a common household bleach - has anyone tried it? I did use it on yellowed ice box handles; wet rugs with bleach wrapped round and then plastic over it to keep it moist. Quite efficient in 24 hours but a perfect result had required probably another handling/more time.

Yoto · 17 July 2008, 12:35

@ Chiark
There is good reason why they peroxide is dangerous, specially if mixed with acetone and sulfuric acid, its a common and cheap explosive.(But also too unstable)

Yoto · 17 July 2008, 12:42

@zipper
Bleach is good to eat thru organic material, and its corrosive so i guess it could speed up the yellowing process, having the opposite result! ( But a test surely wont hurt)

See also:
http://www.vintagecomputing.com/index.php/archives/189

zipper · 17 July 2008, 12:50

Quote:

Originally Posted by Yotoxionomai

@zipper
... and its acid so

Nope, base. NaOHCl, sodium hypochlorite usually. Don't remember the exact pH but 12.5 or thereabouts.

Yoto · 17 July 2008, 13:14

@Zipper
There are both oxydizing bleaches and reducing bleaches so in reality, bleach can be acid or base depending on the type, but my english is not perfect sorry... i changed acid to corrosive

zipper · 17 July 2008, 13:28

Well, I wouldn't call the acid ones as bleach - even if my toilet may look cleaner after a handling. Bleaching needs (mostly) oxidizing potential IMO.
The reducing ones are not so familiar - but as a paper factory using it is hereabouts, I do know them.

Yoto · 17 July 2008, 13:36

Ok, you can try bleach i guess, but wont it remove the letter stamping on keyboard keys?

zipper · 17 July 2008, 13:39

Life is dangerous...

Yoto · 17 July 2008, 13:42

So are Winters in Finland!

17 July 2008, 01:50	#87
Magno Boots Zone Friend Join Date: Feb 2006 Location: Hertfordshire Posts: 688	@ Chiark I couldn't obtain anything stringer than 6% either but don't worry as this works fine. Just a little more time is required. Two 6% bottles from tesco left in a jar for five days in the sun produced fantastic results. Infact the keys turned out brighter than the case I have just painted (white primer only with lacquer finish). This 600 was actually banana coloured one week ago... really.. no kidding, it was close to being binned. The grey keys were only in for one day and need another blast. See current picture.. Attachment 17174 BTW has anyone got a spare Z key as mine has gone walkies? Good luck guys. Last edited by Magno Boots; 17 September 2008 at 23:04.

17 July 2008, 12:09	#91
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	The process involved in reversing the yellowing is very impressive, i wonder...since rich oxigen reverses the process, then the plastic yellowing agent should be related to carbon dioxide, rather than UV or acid compounds. In another approach, CO2 turns water a bit acid, known as carbonic acid, (like the humidity in our fingers and in air), and that may well be why some amiga plastic parts react to CO2 in its acid form or H2CO3 so H2O2 seems to somehow neutralize and reverse it. Well, the CO2 above statements are wrong, H2O2 creates a process that releases the O2 in plastic...how i´m not sure... Last edited by Yoto; 17 July 2008 at 13:08.

17 July 2008, 12:42	#94
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	@zipper Bleach is good to eat thru organic material, and its corrosive so i guess it could speed up the yellowing process, having the opposite result! ( But a test surely wont hurt) See also: http://www.vintagecomputing.com/index.php/archives/189 Last edited by Yoto; 17 July 2008 at 13:30.

17 July 2008, 13:14	#96
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	@Zipper There are both oxydizing bleaches and reducing bleaches so in reality, bleach can be acid or base depending on the type, but my english is not perfect sorry... i changed acid to corrosive Last edited by Yoto; 17 July 2008 at 13:30.

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16 July 2008, 00:10	#81
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,602	Might just go and paint my whole A600 matte black to match the TFT... I know where all the keys are anyway 8) Any suggestions as to what paint to get that gives good results on plastic?

16 July 2008, 01:52	#82
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	I wanted to make something radical to my 1200, maybe to wrap the top case in decalcs from game title covers or amiga magazine covers,(using inkjet transfer paper,and some transparent varnish to cover it all), and for the bottom case, i could just paint it in metalized dark grey, or i could just paint it all in metallic dark grey, carshops usually do those paint jobs quite well...although a bit expensive too...

16 July 2008, 15:44	#83
chiark Needs a life Join Date: Jan 2008 Location: England Posts: 1,707	Well, I went to try and buy some. Boots stock 6%. Sainsburys have 3%. Worryingly, a google search for hydrogen peroxide had a sponsored link from the British Police saying "Suspicious? REPORT IT!"... I can't help but feel that asking for 20-30% H2O2 is drawing attention, even in the small volume I want to bleach the 4000 front back to minty freshness!

16 July 2008, 16:03	#84
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	Really! Here in my country the old ladies buy 60% H2O2 and put 3 single drops in their tea!They are not very smart but at least they make it to the 100 years old...LOL

16 July 2008, 16:41	#85
Merlin AmiBay MegaMod Join Date: Mar 2007 Location: Manchester, UK Age: 62 Posts: 1,163	@ Chiark If you really need some, I'm not too far away from you, perhaps we could arrange a meet somewhere between us, as long as MI5 aren't watching LOL

16 July 2008, 16:58	#86
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	And you could Codename it: 7UP

17 July 2008, 01:54	#88
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@Magno Looks fantastic m8 PM me you deets my friend and a 'Z' will be in the post

17 July 2008, 05:15	#89
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	@Magno: You painted the badge? Mine have the C= logo metallic!

17 July 2008, 10:52	#90
chiark Needs a life Join Date: Jan 2008 Location: England Posts: 1,707	@Magno, Excellent result! I'll go and get the 6% then. The only thing I'm confused about is this thing called "sun" - what's that? I live in the North @Merlin Thanks for the offer - I'll try the 6% @Yotoxionomai I've found 35% available online classed as "food grade" - bloody weird. I might order some... I'll try the face of a 4000 in the 6% stuff... Tempted to mask a bit off, but I know that if I do that I'll never get it to be the same as the other bits!

17 July 2008, 12:34	#92
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,837	What about a common household bleach - has anyone tried it? I did use it on yellowed ice box handles; wet rugs with bleach wrapped round and then plastic over it to keep it moist. Quite efficient in 24 hours but a perfect result had required probably another handling/more time.

17 July 2008, 12:35	#93
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	@ Chiark There is good reason why they peroxide is dangerous, specially if mixed with acetone and sulfuric acid, its a common and cheap explosive.(But also too unstable)

17 July 2008, 13:28	#97
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,837	Well, I wouldn't call the acid ones as bleach - even if my toilet may look cleaner after a handling. Bleaching needs (mostly) oxidizing potential IMO. The reducing ones are not so familiar - but as a paper factory using it is hereabouts, I do know them.

17 July 2008, 13:36	#98
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	Ok, you can try bleach i guess, but wont it remove the letter stamping on keyboard keys?

17 July 2008, 13:39	#99
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,837	Life is dangerous...

17 July 2008, 13:42	#100
Yoto 1 Potato to Spam´em all! Join Date: May 2008 Location: Lost in a Wine Country Age: 47 Posts: 572	So are Winters in Finland!

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