Removing yellowing from Amigas with peroxide - Page 43

Turran · 12 March 2013, 17:55

1: Nope. It will be spent after being in UV light as far as I know. Possibly the 30% type will last for a while but dont bet on it.

2: I usually use some soap for the cables. If that does not work, I've heard chlorine works well on cables (dont use it on hard plastic though)

AndersHP · 12 March 2013, 22:09

Ok thanks.

One last thing; anyone ever tried corn starch/Maizena instead of the xanthan gum?

Seems pretty much easier to get a hold of, but will it interfere with the Retr0bright solution?

demolition · 12 March 2013, 22:17

Yes, I used Maizena corn starch and it worked great for me. Experiment with some pure water to find the correct ratio of fluid/starch before you make it with the much more expensive H2O2. To make corn starch work, you have to heat the solution in the microwave (in small steps) until it loses the milky-white color and becomes more transparent. Only then will the starch thicken the solution. I heat it in a cup, and then cool it off in a cold water bath as I don't like to apply something hot onto plastic as it may get deformed.

Needless to say, as H2O2 isn't healthy for the eyes (or the skin in high concentrations), thick and hot concentrated H2O2 is something one should be very careful with.

Edit: I've had success with adding a bit of Vanish to a week old H2O2+Maizena solution, and I think it should be fine to make a larger batch of thick H2O2 and then just 'activate' it using Vanish once you need to use it. I've not tested reusing a spent batch which had been already used for retrobrighting (once you thicken it properly, you don't really need to use very much).

AndersHP · 13 March 2013, 14:25

Quote:

Originally Posted by demolition

Yes, I used Maizena corn starch and it worked great for me.

Great!

Quote:

Originally Posted by demolition

I've not tested reusing a spent batch which had been already used for retrobrighting (once you thicken it properly, you don't really need to use very much).

My thoughts exactly. The reason I asked, was because I didn't hear about the gum/starch thickening solution 'till recently, so I was planning a H2O2 bath for my Amigas. And that would mean pretty large amounts of liquid!

GadgetUK · 17 March 2013, 22:16

Here's the experience I had with an a1200 (went very well), my 500 grey keys came out a little white though.

http://www.amiga.org/forums/showthread.php?t=64425

AndersHP · 20 March 2013, 07:44

Quote:

Originally Posted by demolition

Yes, I used Maizena corn starch and it worked great for me.

How did you get the peroxide thickened? I've added maybe 8 spoonfuls of Maizena corn starch to 200ml peroxide, and it only gets milky to look at, not thicker....??

I tried heating peroxide in the microwave about 40 secs, but it still doesnt work..

demolition · 20 March 2013, 10:02

Quote:

Originally Posted by AndersHP

How did you get the peroxide thickened? I've added maybe 8 spoonfuls of Maizena corn starch to 200ml peroxide, and it only gets milky to look at, not thicker....??

I tried heating peroxide in the microwave about 40 secs, but it still doesnt work..

As I mentioned, it won't start thickening until you heat it properly (the heat makes the molecules unravel), so you probably didn't heat it enough (I'm guessing somewhere between 60 deg - 80 deg, although I didn't measure it). When it gets to the correct temperature it changes color from milky to more transparent. Give it small 15s doses in the microwave and stir it between each dose to determine when you have reached the right temperature.

Also, 8 spoonfuls for 200ml is probably way too much. Experiment with water and corn starch to find the right ratio before you use actual peroxide.

AndersHP · 21 March 2013, 10:38

Quote:

Originally Posted by demolition

As I mentioned, it won't start thickening until you heat it properly (the heat makes the molecules unravel), so you probably didn't heat it enough

OK thanks. I was a bit afraid to heat the peroxide too much, as it says "danger of explosion if heated" on the bottle...

(BTW, sorry for my ignorance - you already stated this in your previous answer, indeed)

demolition · 21 March 2013, 11:03

Quote:

Originally Posted by AndersHP

OK thanks. I was a bit afraid to heat the peroxide too much, as it says "danger of explosion if heated" on the bottle...

That's odd - it doesn't say anything like that on the peroxide that I bought.. The stuff I got is 10% H2O2 bought in Matas. I didn't know that hydrogen peroxide could be explosive. Maybe if you heat it to boiling, which is why I only give it small doses in the microwave so as to not heat it more than necessary. Also, you'll want to cool it after it has thickened before you use it.

Anyone has some good insight into whether it's wise to heat up H2O2?

Mr B · 21 March 2013, 12:01

Quote:

Originally Posted by demolition

I didn't know that hydrogen peroxide could be explosive.

Uh. It's rocket fuel. It sure can go boom. The likelihood for low % stuff to do it through short bursts of heating, is negligible, if even that. It would need containment if there is to be a boom at that rate. However, you are increasing the rate it releases oxygen, and it could pose a fire hazard. I''m assuming your more likely to oxidize the starch, and produce carbon dioxide, which is why i'm unsure about adding organic matter to the proces of "whitening" an Amiga. But what ever works.

zipper · 21 March 2013, 12:38

Although hydrogen peroxide is non flammable, it can nevertheless form explosive vapors under certain conditions (explosion occurring by decomposition of the vapor rather than combustion). This potential hazard is a function of temperature, pressure, and H2O2 liquid concentration. At atmospheric pressure, boiling 74% hydrogen peroxide (ca. 130 OC) will give a vapor just at the limit of flammability. This "lower explosive limit" for H2O2 vapor is 26 mole % (39 wt. %) at atmospheric pressure.

demolition · 21 March 2013, 13:25

So it sounds like it should be safe enough to heat hydrogen peroxide in the concentrations that regular people can buy it (I can't find higher than 10% here)?

Mr B · 21 March 2013, 14:20

Yeah, as i said, your heating it up, causing it to react faster (decompose) releasing oxygen atoms. 1 finding "something else" oxidizes it, 1 finding another turns in to a minute amount of dioxygen gas, O2, you know, the stuff carbon based life breath to continue live. The presence of higher levels of oxygen can make stuff that usually is hard to set on fire, or simply wont burn, turn in to a viable fire hazard. Again, the amounts here should be minute, and insignificant. Not sure heating hydrogen peroxide is helpful to cure the yellowing, but the hazards should be minimal.

demolition · 21 March 2013, 15:08

Quote:

Originally Posted by Mr B

Not sure heating hydrogen peroxide is helpful to cure the yellowing, but the hazards should be minimal.

The heating is performed as to make the starch thicken the solution. It should be cooled again before being applied (plastic might be deformed from the heat).

Mr B · 21 March 2013, 15:44

The temperature is a direct linked factor to the decay of the peroxide. Heating it accelerates the decay, and oxygen production. (Hydrogen peroxide is used in conjunction with redox controllers for example in aquariums, where they help with disposing of unwanted organic mater, and pumping up the 'breathable' oxygen levels.) This process doesn't reverse when the stuff cools down, so what you end up with is a weaker peroxide solution. Thats what i meant with my comment. Heat, and (sun)light is major factors when it comes to how fast hydrogen peroxide decays, which is why one is recommended to wrap the yellowed stuff up in plastic and leave it in the sun while treating it. Containment, heat, and light.

JonSick · 04 April 2013, 13:21

Just to clear up a confusion (I'm about to do this on my stock).

When the original recipe calls for Peroxide, I take it they don't mean BBlonde?
http://retr0bright.wikispaces.com/Retr0Bright+Gel

So, from that, if I just bought a bottle of BBlonde, applied it and let it sit for a couple of hours in the sun, is that all I need to do?

roy bates · 04 April 2013, 16:21

ive used bblonde,and just painted it on with a brush and leave it.

it took 2 days to change the colur back to normal.

i found keys take longer,even in soak in 35% peroxide.

Methanoid · 04 April 2013, 20:21

Take care. A single day or less actually warped my keys. It wasnt that warm (UK after all) so I would advise a coat and leave for 3-4 hours and clean off. Repeat.

After all Bblonde is cheaper than a new case. I bought a big 1 litre bottle

JonSick · 04 April 2013, 21:41

So, is BBlonde slightly riskier than the Retrobrite solution?

roy bates · 04 April 2013, 21:47

ive had no warpage of the keys and im using 35% hydrogen peroxide neat it a tub for upto a week with no problems.

i just leave them floating in the solution untill they turn back to normal colour.

12 March 2013, 22:17	#843
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	Yes, I used Maizena corn starch and it worked great for me. Experiment with some pure water to find the correct ratio of fluid/starch before you make it with the much more expensive H2O2. To make corn starch work, you have to heat the solution in the microwave (in small steps) until it loses the milky-white color and becomes more transparent. Only then will the starch thicken the solution. I heat it in a cup, and then cool it off in a cold water bath as I don't like to apply something hot onto plastic as it may get deformed. Needless to say, as H2O2 isn't healthy for the eyes (or the skin in high concentrations), thick and hot concentrated H2O2 is something one should be very careful with. Edit: I've had success with adding a bit of Vanish to a week old H2O2+Maizena solution, and I think it should be fine to make a larger batch of thick H2O2 and then just 'activate' it using Vanish once you need to use it. I've not tested reusing a spent batch which had been already used for retrobrighting (once you thicken it properly, you don't really need to use very much). Last edited by demolition; 12 March 2013 at 22:23.

04 April 2013, 20:21	#858
Methanoid Retired Quartex Sysop Join Date: Sep 2001 Location: Roman Verulamium Age: 58 Posts: 1,873	Re: Removing yellowing from Amigas with peroxide Take care. A single day or less actually warped my keys. It wasnt that warm (UK after all) so I would advise a coat and leave for 3-4 hours and clean off. Repeat. After all Bblonde is cheaper than a new case. I bought a big 1 litre bottle

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12 March 2013, 17:55	#841
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,571	1: Nope. It will be spent after being in UV light as far as I know. Possibly the 30% type will last for a while but dont bet on it. 2: I usually use some soap for the cables. If that does not work, I've heard chlorine works well on cables (dont use it on hard plastic though)

12 March 2013, 22:09	#842
AndersHP Registered User Join Date: Aug 2010 Location: Denmark Posts: 124	Ok thanks. One last thing; anyone ever tried corn starch/Maizena instead of the xanthan gum? Seems pretty much easier to get a hold of, but will it interfere with the Retr0bright solution?

17 March 2013, 22:16	#845
GadgetUK Registered User Join Date: Mar 2013 Location: Manchester Posts: 189	Here's the experience I had with an a1200 (went very well), my 500 grey keys came out a little white though. http://www.amiga.org/forums/showthread.php?t=64425

21 March 2013, 12:38	#851
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,837	Although hydrogen peroxide is non flammable, it can nevertheless form explosive vapors under certain conditions (explosion occurring by decomposition of the vapor rather than combustion). This potential hazard is a function of temperature, pressure, and H2O2 liquid concentration. At atmospheric pressure, boiling 74% hydrogen peroxide (ca. 130 OC) will give a vapor just at the limit of flammability. This "lower explosive limit" for H2O2 vapor is 26 mole % (39 wt. %) at atmospheric pressure.

21 March 2013, 13:25	#852
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	So it sounds like it should be safe enough to heat hydrogen peroxide in the concentrations that regular people can buy it (I can't find higher than 10% here)?

21 March 2013, 14:20	#853
Mr B Registered User Join Date: Nov 2005 Location: Sweden Posts: 749	Yeah, as i said, your heating it up, causing it to react faster (decompose) releasing oxygen atoms. 1 finding "something else" oxidizes it, 1 finding another turns in to a minute amount of dioxygen gas, O2, you know, the stuff carbon based life breath to continue live. The presence of higher levels of oxygen can make stuff that usually is hard to set on fire, or simply wont burn, turn in to a viable fire hazard. Again, the amounts here should be minute, and insignificant. Not sure heating hydrogen peroxide is helpful to cure the yellowing, but the hazards should be minimal.

21 March 2013, 15:44	#855
Mr B Registered User Join Date: Nov 2005 Location: Sweden Posts: 749	The temperature is a direct linked factor to the decay of the peroxide. Heating it accelerates the decay, and oxygen production. (Hydrogen peroxide is used in conjunction with redox controllers for example in aquariums, where they help with disposing of unwanted organic mater, and pumping up the 'breathable' oxygen levels.) This process doesn't reverse when the stuff cools down, so what you end up with is a weaker peroxide solution. Thats what i meant with my comment. Heat, and (sun)light is major factors when it comes to how fast hydrogen peroxide decays, which is why one is recommended to wrap the yellowed stuff up in plastic and leave it in the sun while treating it. Containment, heat, and light.

04 April 2013, 13:21	#856
JonSick Registered User Join Date: Oct 2006 Location: London UK Posts: 255	Just to clear up a confusion (I'm about to do this on my stock). When the original recipe calls for Peroxide, I take it they don't mean BBlonde? http://retr0bright.wikispaces.com/Retr0Bright+Gel So, from that, if I just bought a bottle of BBlonde, applied it and let it sit for a couple of hours in the sun, is that all I need to do?

04 April 2013, 16:21	#857
roy bates Registered User Join Date: Apr 2011 Location: birmingham Age: 55 Posts: 2,827	ive used bblonde,and just painted it on with a brush and leave it. it took 2 days to change the colur back to normal. i found keys take longer,even in soak in 35% peroxide.

04 April 2013, 21:41	#859
JonSick Registered User Join Date: Oct 2006 Location: London UK Posts: 255	So, is BBlonde slightly riskier than the Retrobrite solution?

04 April 2013, 21:47	#860
roy bates Registered User Join Date: Apr 2011 Location: birmingham Age: 55 Posts: 2,827	ive had no warpage of the keys and im using 35% hydrogen peroxide neat it a tub for upto a week with no problems. i just leave them floating in the solution untill they turn back to normal colour.

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