> 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.
> “ 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.
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?
Readit News
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.
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?