Posted by bookofjoe 5 days ago
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...
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.
(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?