| Discussion Forum: Thread 340533 |
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| | | Author: | Luloma  | | Posted: | May 29, 2023 12:01 | | Subject: | Whitening process | | Viewed: | 167 times | | Topic: | Help | |
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| I am writing this post because I was wondering if may be possible to obtain the
catalization with the usual procedure for bricks whitening (hydrogen peroxide+UVA)
also wrapping them in a transparent film to preserve the stickers, or if it is
necessary (as I always believed), the direct contact with the material.
Thansk to all
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| | | | | Author: | SylvainLS | | Posted: | May 29, 2023 12:25 | | Subject: | Re: Whitening process | | Viewed: | 59 times | | Topic: | Help | |
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| In Help, Luloma writes:
| | I am writing this post because I was wondering if may be possible to obtain the
catalization with the usual procedure for bricks whitening (hydrogen peroxide+UVA)
also wrapping them in a transparent film to preserve the stickers, or if it is
necessary (as I always believed), the direct contact with the material.
Thansk to all
|
This’s exactly how I do my laundry: I put all my clothes in a hermetic bag before
putting the bag in the machine. The bag gets out really clean!
But I don’t get why people grimace when I’m upwind to them 
IOW: if the peroxide is not in contact with the plastic, how can they react together?
 
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| | | | | | | Author: | Luloma | | Posted: | May 29, 2023 12:34 | | Subject: | Re: Whitening process | | Viewed: | 56 times | | Topic: | Help | |
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| In Help, SylvainLS writes:
| | In Help, Luloma writes:
| | I am writing this post because I was wondering if may be possible to obtain the
catalization with the usual procedure for bricks whitening (hydrogen peroxide+UVA)
also wrapping them in a transparent film to preserve the stickers, or if it is
necessary (as I always believed), the direct contact with the material.
Thansk to all
|
This’s exactly how I do my laundry: I put all my clothes in a hermetic bag before
putting the bag in the machine. The bag gets out really clean!
But I don’t get why people grimace when I’m upwind to them
IOW: if the peroxide is not in contact with the plastic, how can they react together?
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LOL. By the way, to reply your answer: I just thouth that maybe it's
not about the contact, but about the way the rays hit the plastic after passing
through the hydrogen peroxide!
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| | | | | | | | | Author: | SylvainLS | | Posted: | May 29, 2023 13:52 | | Subject: | Re: Whitening process | | Viewed: | 55 times | | Topic: | Help | |
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| In Help, Luloma writes:
| | […]
LOL. By the way, to reply your answer: I just thouth that maybe it's
not about the contact, but about the way the rays hit the plastic after passing
through the hydrogen peroxide!
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Er, no that’s not how it works.
Last I looked, it would be the “bleaching”/“whitening” effect of the peroxide:
it transforms some molecules so they don’t absorb/reflect the light the same
way, thus changing (back) the apparent colour.
But that doesn’t repair the degraded plastic: it degrades the molecules that
were created by the degradation of the plastic (and may help degrade the plastic
further too).
yellowing:
ABS + (light and/or heat + oxygen) → degraded-ABS + yellow-stuff
whitening:
degraded-ABS + yellow-stuff + UVs + oxygen → degraded-ABS + whitened-yellow-stuff
Whatever you choose to do:
1. Avoid direct sunlight: it has UVc that are very bad for the plastic (and you).
(Put everything behing some glass.)
2. Tell your buyers.
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| | | | | | | | | | | Author: | Luloma | | Posted: | May 29, 2023 17:31 | | Subject: | Re: Whitening process | | Viewed: | 45 times | | Topic: | Help | |
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| In Help, SylvainLS writes:
| | In Help, Luloma writes:
| | […]
LOL. By the way, to reply your answer: I just thouth that maybe it's
not about the contact, but about the way the rays hit the plastic after passing
through the hydrogen peroxide!
|
Er, no that’s not how it works.
Last I looked, it would be the “bleaching”/“whitening” effect of the peroxide:
it transforms some molecules so they don’t absorb/reflect the light the same
way, thus changing (back) the apparent colour.
But that doesn’t repair the degraded plastic: it degrades the molecules that
were created by the degradation of the plastic (and may help degrade the plastic
further too).
yellowing:
ABS + (light and/or heat + oxygen) → degraded-ABS + yellow-stuff
whitening:
degraded-ABS + yellow-stuff + UVs + oxygen → degraded-ABS + whitened-yellow-stuff
Whatever you choose to do:
1. Avoid direct sunlight: it has UVc that are very bad for the plastic (and you).
(Put everything behing some glass.)
2. Tell your buyers.
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Thanks for your detailed explanation, and for your time. My buyers are fully
briefed, that's my primary mission! and I needed this informations for my
personal development, not for my inventory.
Have a nice evening!
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| | | | | | | Author: | leggodtshop | | Posted: | May 29, 2023 17:57 | | Subject: | Re: Whitening process | | Viewed: | 65 times | | Topic: | Help | |
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| In Help, SylvainLS writes:
| | In Help, Luloma writes:
| | I am writing this post because I was wondering if may be possible to obtain the
catalization with the usual procedure for bricks whitening (hydrogen peroxide+UVA)
also wrapping them in a transparent film to preserve the stickers, or if it is
necessary (as I always believed), the direct contact with the material.
Thansk to all
|
This’s exactly how I do my laundry: I put all my clothes in a hermetic bag before
putting the bag in the machine. The bag gets out really clean!
But I don’t get why people grimace when I’m upwind to them
IOW: if the peroxide is not in contact with the plastic, how can they react together?
|
My experience on (older) discolored items...
Although peroxide works on discolored white parts, it does not (properly) work
on discolored blue or grey parts.
However putting the items behind glass (e.g. HR+, HR++) in sunlight does work
on discolored white, blue and grey items. Maybe not all, maybe not perfectly
but I have had good results over the past years. Other colors I don't know.
Discoloring however may return after some time.
BR,
Paul
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| | | | | Author: | MiniRoz | | Posted: | May 29, 2023 12:29 | | Subject: | Re: Whitening process | | Viewed: | 58 times | | Topic: | Help | |
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| In Help, Luloma writes:
| | I am writing this post because I was wondering if may be possible to obtain the
catalization with the usual procedure for bricks whitening (hydrogen peroxide+UVA)
also wrapping them in a transparent film to preserve the stickers, or if it is
necessary (as I always believed), the direct contact with the material.
Thansk to all
|
I’m not sure I 100% understand your question, so forgive me if this reply doesn’t
answer it. Hydrogen Peroxide does not need a “catalyst” to to whiten, but UV
rays seem to help it with the oxidation process. Hydrogen peroxide is the main
active ingredient in most teeth whitening products, and they do not require UV
rays. As far as whitening LEGO, putting white parts in a clear container in direct
sunlight for at least 6 hours definitely helps remove discoloration. This happens
bc it targets electrons and sort of breaks down the atoms that cause staining.
I have no evidence that this harms the parts, but I would not use this process
on bricks I would sell because it seems like anything that causes molecules to
fall apart can’t be good for the integrity of LEGO. Again, I have no evidence,
and humans use it on their these without damaging the enamel, so maybe do a google
search.
As far as using that method on a part with a sticker, I definitely would not
try that, even with plastic wrap over the sticker (not sure how that would even
work). Hydrogen peroxide can and will get under the edges of stickers and loosen
them - you know how you pour it on a little paper cut and it starts to bubble?
That, but under a sticker. If you’re hell bent on it, don’t try to just cover
the sticker with plastic wrap.
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