Questions about using hydrogen peroxide (and other methods) to restore colour to a very special piece (Expedition Balloon)

[Autumn]

Recently I got set 5956 Expedition Balloon but the blimp / zeppelin itself is a little yellowed and so I've been thinking of using hydrogen peroxide to restore the colour (once the British sun comes back! Two big concerns I have however:

Firstly, I have read that the yellow discolouration still returns quickly and worse than before regardless if it is kept out of direct sunlight or not though I am mindful to keep my Lego out of it. I do not want this to happen.

Secondly, the two blimp sections are thinner and more flexible than your usual Lego pieces which makes me worried that the H2O2 could irreversably damage it. It is already prone to denting and stress marks where it screws together. Hydrogen peroxide supposedly affects different types of plastic differently and it's likely the blimp is made from something different to a regular Lego brick.

Would it be a good or bad idea to do it this way? I want to know what other ways there are to do it but I'm having a hard timing finding any that are tried and tested as much.

Another thing I was also thinking of was using some sort of spray paint instead since I know some people create custom parts and minifigs that way. Maybe even a colour that matches light bluish gray since I am hoping to make a more modernised recreation of the set sometime.

Thoughts? Suggestions? Advice? :)

Edited February 6 by Autumn

[AmperZand]

 

@Autumn  To the hydrogen peroxide add a good amount Vanish Oxi Action Crystal White.

The yellowing won’t return any faster than before. I used the above method for some parts in 2014 and have kept them in the dark since. They remain just as white as new parts from the same time (see image).

Using hydrogen peroxide + Crystal White + sunlight doesn’t make parts any more brittle. However, it does give the part a slicker, glassy feel which some people interpret as being more fragile because of the association of glass with fragility. There’s no empirical or chemical reason to believe that’s the case.

I’m not the right AFOL to ask about painting LEGO. @Wardancer is an expert in that.

Edited February 6 by AmperZand

[ukbajadave]

Can't help with the Hydrogen situation but I see this is not a cheap part, £40 or thereabouts. I'd be cautious of anything I thought might damage it permanently so for paint have you considered plasti-dip? You can usually peel it off after painting.

 

[1963maniac]

3 hours ago, AmperZand said:

The yellowing won’t return any faster than before. I used the above method for some parts in 2014 and have kept them in the dark since. They remain just as white as new parts from the same time (see image).

Using hydrogen peroxide + Crystal White + sunlight doesn’t make parts any more brittle. However, it does give the part a slicker, glassy feel which some people interpret as being more fragile because of the association of glass with fragility. There’s no empirical or chemical reason to believe that’s the case.

What "above method" are you referring to? Why add "Crystal White" and what is the formula? Thanks!

[Wardancer]

Hmm thanks for summoning me here. i have been thinking about spraypainting my Smaug for a while, an idea which has some similarities with trying to paint the balloon. 

What I like about the bleaching idea is that it avoids most disadvantages of spraypainting:

- you have to know what you are doing or else you will get an uneven result, spraying is not only easy, especially on 3d objects. Practice a little if you need to.

- most paints do not like anything that moves, bends or gets scratched. You mention the softer parts. Your result might be something you have to be very careful with.

- colour matching with mixing little pots as I do is easy, but mixing sprays needs airbrush equipment. Or you get lucky and find a good Match straight from the can. Or you accept a color that is not exactly a replica of lego. I could Imagine that with the balloon, it is so big it can have its own color.

Intuitively I think bleaching it is a better way. What Amperzand writes sounds very reasonable. The best way would be to try it first on a cheaper part. But if it is a special material this is difficult.

I have been looking for ways to change the color of rubber (Smaugs Wings). There are some paints that instead of covering the object with a layer of paint they go inside the rubber and thereby the object remains flexible. Paint for rubber boats for example is called „elastic“. But I have Not tried anything yet. 

Edited February 6 by Wardancer

[Autumn]

4 hours ago, AmperZand said:

 

@Autumn  To the hydrogen peroxide add a good amount Vanish Oxi Action Crystal White.

The yellowing won’t return any faster than before. I used the above method for some parts in 2014 and have kept them in the dark since. They remain just as white as new parts from the same time (see image).

Using hydrogen peroxide + Crystal White + sunlight doesn’t make parts any more brittle. However, it does give the part a slicker, glassy feel which some people interpret as being more fragile because of the association of glass with fragility. There’s no empirical or chemical reason to believe that’s the case.

I’m not the right AFOL to ask about painting LEGO. @Wardancer is an expert in that.

How does Vanish help? And, like @1963maniac said, what formula? I've read 3% hydrogen peroxide works fine, but how much Vanish should I add roughly, like grams per litre for example?

4 hours ago, ukbajadave said:

Can't help with the Hydrogen situation but I see this is not a cheap part, £40 or thereabouts. I'd be cautious of anything I thought might damage it permanently so for paint have you considered plasti-dip? You can usually peel it off after painting.

I paid £45 for my blimp. It took a bit of patience to find so really don't want to mess up as I probably will only have one chance. Hopefully I can restore the colour and apply some replacement stickers so it looks fresh!

I have not heard of plasti-dip being used for Lego. My first look into it, it seems a bit odd as though it's a sort of rubber coating? Not sure if that's an ideal solution but I will do a bit more research.

53 minutes ago, Wardancer said:

Hmm thanks for summoning me here. i have been thinking about spraypainting my Smaug for a while, an idea which has some similarities with trying to paint the balloon. 

What I like about the bleaching idea is that it avoids most disadvantages of spraypainting:

- you have to know what you are doing or else you will get an uneven result, spraying is not only easy, especially on 3d objects. Practice a little if you need to.

- most paints do not like anything that moves, bends or gets scratched. You mention the softer parts. Your result might be something you have to be very careful with.

- colour matching with mixing little pots as I do is easy, but mixing sprays needs airbrush equipment. Or you get lucky and find a good Match straight from the can. Or you accept a color that is not exactly a replica of lego. I could Imagine that with the balloon, it is so big it can have its own color.

Intuitively I think bleaching it is a better way. What Amperzand writes sounds very reasonable. The best way would be to try it first on a cheaper part. But if it is a special material this is difficult.

I have been looking for ways to change the color of rubber (Smaugs Wings). There are some paints that instead of covering the object with a layer of paint they go inside the rubber and thereby the object remains flexible. But I have Not tried anything yet.

Some of your points were what I was already considering, like equipment expense, adhesion of paint to a flexible surface, my lack of experience.

Thanks for your input, I think I will stay away from this method at least for now. That special paint you mentioned sounds interesting though.

Edited February 6 by Autumn

[Elephant Knight]

I have used the Hydrogen peroxide method a few times, and haven't noticed any reyellowing.

But I haven't had much luck in bringing grey back to it's original colour. Most white parts come back to being white, or at least closer to white. Often when I treat grey pieces, it isn't affected much at all, or it comes out an off shade, and a bit bright. But at the same time, the grey parts I have treated tend to be the very bad ones.

As for the stickers, people seem to say it destroys stickers, and while the stickers don't survive unscathed, they don't completely destroy. Stickers that are printed onto white tend to have many small hairline cracks appear on them, sometimes not even noticeable at a distance. and stickers printed on clear it's even less noticeable.

Restoring yellowed parts by Elephant-Knight, on Flickr

Picture isn't the greatest, but you can see that the sticker really isn't any worse for wear. It was pretty rough to begin with, though.

EKnight

[Autumn]

5 hours ago, Elephant Knight said:

I have used the Hydrogen peroxide method a few times, and haven't noticed any reyellowing.

But I haven't had much luck in bringing grey back to it's original colour. Most white parts come back to being white, or at least closer to white. Often when I treat grey pieces, it isn't affected much at all, or it comes out an off shade, and a bit bright. But at the same time, the grey parts I have treated tend to be the very bad ones.

As for the stickers, people seem to say it destroys stickers, and while the stickers don't survive unscathed, they don't completely destroy. Stickers that are printed onto white tend to have many small hairline cracks appear on them, sometimes not even noticeable at a distance. and stickers printed on clear it's even less noticeable.

Restoring yellowed parts by Elephant-Knight, on Flickr

Picture isn't the greatest, but you can see that the sticker really isn't any worse for wear. It was pretty rough to begin with, though.

EKnight

The blimp I have isn't nearly that yellow, though it might be a bit hard to compare off-white to off-gray. There are a few stickers on it but I will remove them first since I am going to buy a full replacement set anyway if it turns out well.

[AmperZand]

@Autumn , I didn’t realise the part was originally light grey, not white! I didn’t know until I looked up the set’s inventory just now. Not sure how well it would work as I’ve only ever done it to white parts, hence the addition of the Crystal White.

@Elephant Knight reports above only limited success with hydrogen peroxide and that doesn’t surprise me. I don’t think there’s any risk, but you shouldn’t get your hopes up of it fully restoring the original colour. Instead of Crystal White, you may want to add regular Vanish powder instead - about 5% to 10% to hydrogen peroxide by volume. Note that the mixture gets hot - the reaction is exothermic - and froths like mad, so you want to do it in a glass jar or bowl with a tray or similar underneath for the overspill/frothing. The Vanish acts as a catalyst, hugely accelerating the process. What takes a day without Vanish, takes an hour with it.

[MAB]

21 hours ago, Wardancer said:

I have been looking for ways to change the color of rubber (Smaugs Wings). There are some paints that instead of covering the object with a layer of paint they go inside the rubber and thereby the object remains flexible. Paint for rubber boats for example is called „elastic“. But I have Not tried anything yet. 

Years ago, I dyed the flexible rubber tail part and the brick from a Duplo zooter. I left it in warm but not hot dye for a couple of days and it eventually went black. Just reheating it every few hours.

I also tried some 60s train wheels (the treads) but they fell apart. 

I'm not sure I'd try Smaug's wings though. Maybe a fake one but even those are expensive. 

[Autumn]

4 hours ago, AmperZand said:

@Autumn , I didn’t realise the part was originally light grey, not white! I didn’t know until I looked up the set’s inventory just now. Not sure how well it would work as I’ve only ever done it to white parts, hence the addition of the Crystal White.

@Elephant Knight reports above only limited success with hydrogen peroxide and that doesn’t surprise me. I don’t think there’s any risk, but you shouldn’t get your hopes up of it fully restoring the original colour. Instead of Crystal White, you may want to add regular Vanish powder instead - about 5% to 10% to hydrogen peroxide by volume. Note that the mixture gets hot - the reaction is exothermic - and froths like mad, so you want to do it in a glass jar or bowl with a tray or similar underneath for the overspill/frothing. The Vanish acts as a catalyst, hugely accelerating the process. What takes a day without Vanish, takes an hour with it.

I have seen some people do it on old light gray parts with success, but most focus on white. Some have shown dark gray and blue get a weird marble effect afterwards but light gray seems to come out okay.

Thanks for the clarification on the proportions, would you still need UV or sunlight if using Vanish?

Edited February 7 by Autumn

[AmperZand]

@Autumn , I used sunlight as well as Vanish but whether it’s strictly necessary is uncertain. If you can do it on a window sill, that’s probably better but likely not a deal breaker if not.

[Toastie]

22 hours ago, AmperZand said:

I used sunlight as well as Vanish but whether it’s strictly necessary is uncertain.

I believe this whole retro-brighting approach has so many aspects, it is really tough to tell, what works in what "case".

I just wrote a way too long post (and I bet I will get a lot of flak for that content) in the Technic forum/CaDA (https://www.eurobricks.com/forum/index.php?/forums/topic/189501-cada-cada-general-discussion-topic/&do=findComment&comment=3681951), mostly touching on ABS as such and (scroll down - yellowing and retro-brighting.

The entire process is based on oxidation - Vanish = "O2" oxidation, H2O2 = "OH" oxidation. The yellowing is - as far as I am concerned after extensive literature surveys - breaking double bonds in the ABS polymer, leaving a single bond and free or better delocalized electrons. These cause the absorption of a portion of the "white light" shining on them - leading to yellowing (white = no absorption of "white" light). And they can be "removed" upon oxidation = making a new bond with "O2" or "OH" which does not absorb any of the visible light wavelengths.

In other words: Whatever active oxidation compound can penetrate through the ABS material to "remove" or better "bind" the free/delocalized electrons. H2O2 is quite good, but you need to crack it first into two OH radicals, which is easily done with UV light. Vanish is activated by heat to yield oxygen "in statu nascendi" = O atoms rapidly recombining to O2 (and then they are "dead" with regard to oxidation power). So the O atoms initially produced upon heat mediated decomposition of Vanish need to find these free electrons before recombining to O2. H2O2 does not decompose into 2 OH radicals with heat, but with UV light.

In other words: H2O2 needs UV light to activate, Vanish heat. Mixing both + heat + UV light may accelerate the overall oxidation process.

I'd use as high as possible concentrated H2O2 aqueous solutions + UV light (sun/LEDs). Problem is: The authorities don't like to let us easily get 80% H2O2 solutions - you can make so many really bad/cool things with it. Just look up "The Blue Flame" for example, which is totally cool. NASA is also fond of it. And: The 80% solution works fast - and then may bite into the plastic as well. As said, retro-brighting is an entire philosophy among the retro-folks (computers, game pads, whatnot)

Best,
Thorsten

 

Edited February 8 by Toastie

[The Reader]

10 hours ago, Toastie said:

I believe this whole retro-brighting approach has so many aspects, it is really tough to tell, what works in what "case".

I just wrote a way too long post (and I bet I will get a lot of flak for that content) in the Technic forum/CaDA (https://www.eurobricks.com/forum/index.php?/forums/topic/189501-cada-cada-general-discussion-topic/&do=findComment&comment=3681951), mostly touching on ABS as such and (scroll down - yellowing and retro-brighting.

The entire process is based on oxidation - Vanish = "O2" oxidation, H2O2 = "OH" oxidation. The yellowing is - as far as I am concerned after extensive literature surveys - breaking double bonds in the ABS polymer, leaving a single bond and free or better delocalized electrons. These cause the absorption of a portion of the "white light" shining on them - leading to yellowing (white = no absorption of "white" light). And they can be "removed" upon oxidation = making a new bond with "O2" or "OH" which does not absorb any of the visible light wavelengths.

In other words: Whatever active oxidation compound can penetrate through the ABS material to "remove" or better "bind" the free/delocalized electrons. H2O2 is quite good, but you need to crack it first into two OH radicals, which is easily done with UV light. Vanish is activated by heat to yield oxygen "in statu nascendi" = O atoms rapidly recombining to O2 (and then they are "dead" with regard to oxidation power). So the O atoms initially produced upon heat mediated decomposition of Vanish need to find these free electrons before recombining to O2. H2O2 does not decompose into 2 OH radicals with heat, but with UV light.

In other words: H2O2 needs UV light to activate, Vanish heat. Mixing both + heat + UV light may accelerate the overall oxidation process.

I'd use as high as possible concentrated H2O2 aqueous solutions + UV light (sun/LEDs). Problem is: The authorities don't like to let us easily get 80% H2O2 solutions - you can make so many really bad/cool things with it. Just look up "The Blue Flame" for example, which is totally cool. NASA is also fond of it. And: The 80% solution works fast - and then may bite into the plastic as well. As said, retro-brighting is an entire philosophy among the retro-folks (computers, game pads, whatnot)

Best,
Thorsten

 

Thank you very much for the chemical explanation. 👍

And - I like your style! 😃