> The blue light reduced the yellow stain substantially more than hydrogen peroxide or UV exposure. In fact, UV exposure generated some new yellow-colored compounds.
Here's the key piece of information for me, it's not just light doing this or higher energy blue being close enough to UV to get things done, the blue light tested outperforms UV at destroying some of these yellowing compounds.
It would be nice in followup research to see Figure S8 [1] with an additional dimension for irradiation with various frequencies, not just 445 nm.
It looks like Amazon has some "therapy bulbs"[2] close to the correct frequency for $30, now I wish I hadn't thrown away some of those old yellowed pillows so I could do some science.
There's even special formulas of hydrogen peroxide, arrowroot, and oxyclean, with raging debates on the proper ratios, how long to keep them in the sun, etc:
I feel like the removal of yellowing from things like Apple II computers known colloquially as 'retrobriting' as showing in your video is more the use of peroxide compounds which are not used in the article.
"The blue light reduced the yellow stain substantially more than hydrogen peroxide or UV exposure. In fact, UV exposure generated some new yellow-colored compounds."
There is probably some math to do about the availability of free radicals from bleach versus a set period of sunlight at a certain time of year, in a certain part of the world.
I tried drying linens and clothes outside the first time I moved from an apartment (with strict controls on what can and cannot be seen on the balcony) to a single family home. I quickly stopped because there was so much dust that would accumulate on your freshly washed clothes in the time they were hung outside. That's not to mention bird poop or feral cats deciding to do some stretching on your sheets.
That's no longer "basic low tech from centuries ago" any more. Centuries ago there wasn't transparent glass, only colored glass (think stained glass in an old church).
> “ After heating the swatches to simulate aging, they treated the samples for 10 minutes, by soaking them in a hydrogen peroxide solution or exposing them to the blue LED or UV light. The blue light reduced the yellow stain substantially more than hydrogen peroxide or UV exposure. In fact, UV exposure generated some new yellow-colored compounds.”
They did test with UV light. The sun is broadband (it will have both blue light and uv light) so it works to a degree. The insight is that uv generates some new yellow coloured compounds and only using blue light prevents this.
In my experience no not really. I'm sure it has some effect but compared to chemical bleach or even just using a clothes dryer the wear is not noticeable.
When you do it with actual flax linen it is quite stiff afterwards and it may form permanent creases if you treat it in certain ways immediately after, depending on the weave. But that's to some extent always true with linen.
I'm not a chemist but my two cents because I studied a course of Industrial Inorganic Chemistry in my college. My professor of that course used to say Hydrogen Peroxide is a very strong carcinogen. So I hate every Tom Dick n Harry that yaps about the goodness of Hydrogen Peroxide on YouTube or elsewhere without mentioning that it will give you cancer even in small amounts. And yes UV disintegrates the fibres so the more you keep your clothes in the sun or in UV then they will look old. Source: I live in India with too much UV andif I keep anything under the sun for a couple of days then it looks old or atleast no more new to be worn fashionably.
Your professor was teaching Industrial chemistry. At industrial (undiluted) strengths, there aren’t many chemicals that can’t damage tissue or potentially cause cancer. Constantly breathing the undiluted fumes or other exposures will certainly carry some risk in an Industrial application.
Washing clothes in a dilute peroxide solution is not going to cause cancer, therefore simply walking outside to hang your clothes carries substantially more cancer risk than the use of Hydrogen Peroxide.
Saying it causes cancer in “small amounts” is a bit like shouting at someone that stepping on a twig is destroying the entire forest…while standing next to an inferno.
I’m neither ingesting, inhaling, nor bathing in it, so I don’t care either, nor would I be concerned to wash my hands in it were it needed. Just drinking water or being outside is more than enough exposure to cancer to be worried about.
Well, it's part of the cancer process; most cancers couldn't survive without it. But that's also true of, for example, local production of DNA, or anaerobic glycolysis, or angioneogenesis.
It's not true that if you expose tissues to lots of H₂O₂ they'll get cancer.
I'm also not a chemist... but I do have a PhD in mtls science from a top 10 program. My dissertation was on computational chemistry on organic compounds.
You're 100% right.
As long as the photon is energetic enough, it can cause a radical and therefore break a chemical bond.
Brighter the sunlight, more peroxides (or radicals) made, more damage to your skin or your cloth's fibers.
This is also why anti-oxidants are so effective at protecting the body, why inflammation is so damaging (body produces peroxides to eliminate what it believes is a threat), over consumption of food, too much/little exercise, etc. they all affect peroxide concentration or their halflife.
right, been glancing at this thread, and what occured to me is that blue light from LED's having a bleaching effect, specificly on yellow(cebum) organic compounds, then implys that it's not just(famously) hard on our eyes, it's frying them, and possibly worse.
I certainly mind a brite screen, and keep it at the minimum level, except when in sunlight or useing my phone to show family and customers things.
There are other effects to mass use of high powere LED's, where seagulls are flying around in downtown Halifax, NS in.the middle of the night, which I see now, but never happened with the old mercury vapour street lighting, which was it's own kind of wierd, in that it's bright yellow light from a distance, but makes everything under them monocromatic.IE: something in.the LED light wakes birds up.
I wonder if this is related to yellowing plastics? Retr0brighting with peroxide and sunbriting (putting yellowed plastics out in the sun) are already common treatments in the retro community. I’ll have to give it a try on some of my old hardware
This changes the best practice for retr0brighting from using UV or sunlight to 445nm blue LED. I already knew from anecdotes that sunlight seemed more effective than a UV lamp. People assumed it was the extra heat, which may or may not still be a contributing factor, but I guess it's the blue light prt of the sun's spectrum.
UV can trigger the chemical reactions within the plastics that yellow the plastics, but UV + peroxide does a different chemical reaction to bleach them.
LED packages are designed to radiate the heat in the opposite direction of the light, and they would need to be sealed behind some barrier away from the damp clothes anyway.
1.25 watt/centimeter² ~= 853.75 lumen/centimeter², eg. not a terribly exotic brightness assuming you are ok treating a small area at a time. One of those small LED light panels would probably be in the right ballpark if you positioned it very close to the target.
Let's model a shirt with a cylinder, and let's flat it in to rectangle. Some 50 cm x 100 cm could be OK for a quick estimate. It's 5000 cm, so 6.25 kW if we want to make it work fast. The OP wrote about 10 minutes. Let's relax it to a little more than 1 kW not to be inconvenient to other home activities and we get a 1 hour time. Probably that will help with heat management too.
But 50x100 is not particularly large (think of bed linen) and yet it could take a lot of space in a house. Maybe some small area handheld device that one can apply to stains and leave it there until it turns off with a timer?
I would not expect the effects to be in the same ballpark. Bleaching is very harsh, to the point where I wouldn't want to put my hand in a jug of bleach. I could imagine holding my hand up to a strong light. Sure, it might get too hot or too uncomfortable eventually, but at least in my mind, I would expect it to be lesser (so long as we don't talk about a literal deathray lamp).
What intensity is “high-intensity?” The article doesn’t give a number. Is this something that can be done with a few bright LEDs or do you need a specialized lighting array?
If you follow the links to the supplementary info it gives you intensity level, for example "The prepared dish was placed in a blue LED irradiation device and irradiated at 1.25 W/cm2 for 3 h."
As a reference, noon sunlight is very roughly 1000 W/m^2 or 0.1 W/cm^2, so this is pretty intense and I suspect would not be eye safe.
Jokes aside, I suppose it's novel in the sense that it can be achieved with artificial _blue_ light.
My understanding was that it was various forms of UV from the sun that caused "bleaching", whereas the paper points out that it is not UV in this case, and in fact, the UV can cause additional staining.
Maybe I should have emphasised the word "artificial" rather than the word "blue", the implication was that it's not the only type of blue light, the sun being the obvious one.
The thing about the sun is, you get no light when there's no sun, and some countries don't even get daylight for several months of the year!
It's an interesting idea, and how it would work with colours other than "bleached" would be the interesting part.
Presumably it wouldn't work on black without fading the garment, but given how we've seen things fade in shop windows, I wonder if there's some novel applications for removing other types of intentional "stains" like ink, or paint, and particularly if they're under/behind a surface like a clear-coat or glass or something else that prevents physical access.
That would be an interesting one, I have a strangely related story that not too long ago my toddler drew _all over_ a yellow suede sofa with a blue ballpoint pen, was a nightmare to get it out without making the pristine sofa look like a drowned rat.
I am a common "poo-pooer" of bad submissions on here, and comments not in good faith
But this paper taught me something I had no idea about as a 33 year old.
Also in the comment chain someone mentioned/brought up using peroxide/sunlight to clear up old yellowed plastics which is....monumental to some of my projects :)
Ultraviolet light is ionizing. Things oxidize and often whiten in sun because the UV light (the part of the UV spectrum as you go below ~315nm) ionizes and causes chemical reactions, in most cases by splitting O2 which is then charged O atoms that want to react with things.
445nm light isn't ionizing at any brightness, and shouldn't be catalyzing oxidation. Didn't look at it in detail but what is their claim on mechanism?
Here's the key piece of information for me, it's not just light doing this or higher energy blue being close enough to UV to get things done, the blue light tested outperforms UV at destroying some of these yellowing compounds.
It would be nice in followup research to see Figure S8 [1] with an additional dimension for irradiation with various frequencies, not just 445 nm.
It looks like Amazon has some "therapy bulbs"[2] close to the correct frequency for $30, now I wish I hadn't thrown away some of those old yellowed pillows so I could do some science.
1. https://pubs.acs.org/doi/10.1021/acssuschemeng.5c03907
2. https://www.amazon.com/Aumtrly-Light-Therapy-Irradiance-Cove...
https://youtu.be/aFGS9xaaO_M
There's even special formulas of hydrogen peroxide, arrowroot, and oxyclean, with raging debates on the proper ratios, how long to keep them in the sun, etc:
https://www.callapple.org/vintage-apple-computers/apple-ii/s...
"The blue light reduced the yellow stain substantially more than hydrogen peroxide or UV exposure. In fact, UV exposure generated some new yellow-colored compounds."
I dry my linens outside (I'm not American), and no chemical bleach beats the effectiveness of the sun turning oxygen and water to peroxide.
https://en.wikipedia.org/wiki/Flemish_Market_and_Washing_Pla...
Though I think this is possibly a depiction of a step in linen production, rather than the maintenance of used linen.
But anyway yeah it used to be a normal part of life people were used to seeing.
https://en.wikipedia.org/wiki/Bleachfield
They did test with UV light. The sun is broadband (it will have both blue light and uv light) so it works to a degree. The insight is that uv generates some new yellow coloured compounds and only using blue light prevents this.
For instance "color-bleach" (which I guess is peroxide with other stuff) makes cloths disintegrate if used too often
When you do it with actual flax linen it is quite stiff afterwards and it may form permanent creases if you treat it in certain ways immediately after, depending on the weave. But that's to some extent always true with linen.
Washing clothes in a dilute peroxide solution is not going to cause cancer, therefore simply walking outside to hang your clothes carries substantially more cancer risk than the use of Hydrogen Peroxide.
Saying it causes cancer in “small amounts” is a bit like shouting at someone that stepping on a twig is destroying the entire forest…while standing next to an inferno.
I dont, but I dont care.
It's not true that if you expose tissues to lots of H₂O₂ they'll get cancer.
You're 100% right.
As long as the photon is energetic enough, it can cause a radical and therefore break a chemical bond.
Brighter the sunlight, more peroxides (or radicals) made, more damage to your skin or your cloth's fibers.
This is also why anti-oxidants are so effective at protecting the body, why inflammation is so damaging (body produces peroxides to eliminate what it believes is a threat), over consumption of food, too much/little exercise, etc. they all affect peroxide concentration or their halflife.
When I lived overseas my laundry was often dried in the sun and it’s amazing how fast the color is bleached out.
(Also, the additional energy/heat will help drying, so you pay for the hardware but the energy consumption for the light is totally free.)
> 445 nm; 1.25 W/cm2
But 50x100 is not particularly large (think of bed linen) and yet it could take a lot of space in a house. Maybe some small area handheld device that one can apply to stains and leave it there until it turns off with a timer?
https://thebrickblogger.com/2020/06/restoring-discolored-leg...
You don't use concentrated bleach on clothing... You diluted it. It's only provided concentrated for storage convenience
As a reference, noon sunlight is very roughly 1000 W/m^2 or 0.1 W/cm^2, so this is pretty intense and I suspect would not be eye safe.
See https://pubs.acs.org/doi/suppl/10.1021/acssuschemeng.5c03907....
Jokes aside, I suppose it's novel in the sense that it can be achieved with artificial _blue_ light.
My understanding was that it was various forms of UV from the sun that caused "bleaching", whereas the paper points out that it is not UV in this case, and in fact, the UV can cause additional staining.
EDIT: Edited for grammar.
The thing about the sun is, you get no light when there's no sun, and some countries don't even get daylight for several months of the year!
Take a color that is maximally absorbed by the stain and thus get the most energy into it without affecting too much else.
I wonder if that would work with other colors as well.
Presumably it wouldn't work on black without fading the garment, but given how we've seen things fade in shop windows, I wonder if there's some novel applications for removing other types of intentional "stains" like ink, or paint, and particularly if they're under/behind a surface like a clear-coat or glass or something else that prevents physical access.
But this paper taught me something I had no idea about as a 33 year old. Also in the comment chain someone mentioned/brought up using peroxide/sunlight to clear up old yellowed plastics which is....monumental to some of my projects :)
ty, too much coffee this morning
445nm light isn't ionizing at any brightness, and shouldn't be catalyzing oxidation. Didn't look at it in detail but what is their claim on mechanism?
I think standard glass blocks UVB and car windscreens often block UVA and UVB.
Then put in the strongest 455mm wavelength diode you can find off Digikey that fits the kit parts.
https://www.spectrumwiki.com/wiki/display.aspx?f=659000000&l...