Don’t buy anything. Use the sun, for the moment it’s free.

Given the bits about UV, using the sun plus a glass window might be better?

I think standard glass blocks UVB and car windscreens often block UVA and UVB.

Or existing oxygen based cleaning products. The sun can cause other damage, it’s a balance

https://news.ycombinator.com/item?id=45209124 mentions that simply putting the stained cloth under the sun works.

You can buy blue led strips just about everywhere.

Buy some diy flashlight kit. There's an entire community of people that build flashlights for fun and hence a ecosystem of parts.

Then put in the strongest 455mm wavelength diode you can find off Digikey that fits the kit parts.

Haha, 455mm! That's 659MHz, which used to be channel 45 for UHF TVs in the US: https://en.m.wikipedia.org/wiki/Television_channel_frequenci... but has it been reallocated to something else like LTE?

https://www.spectrumwiki.com/wiki/display.aspx?f=659000000&l...

*nm, as in nanometers.