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.
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.
> 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?
(Also, the additional energy/heat will help drying, so you pay for the hardware but the energy consumption for the light is totally free.)
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...
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 :)
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...