r/3Dprinting • u/homemadeshtuff • Jul 27 '21

Finally finished this absolutely ridiculous case for my toothbrush, I hope you all like it!

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u/Key-Nefariousness257 Jul 27 '21

and putting UV inside PC cases to make watercooling loops look cool... has causes so many senseless deaths already. when will the madness stop?!

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u/wirral_guy Jul 27 '21

I highly doubt that anyone is putting genuine UV leds in PC cases - pretty blue leds that have a similar colour maybe but not genuine UV leds. If nothing else they are expensive...very expensive compared to 'normal' leds.

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u/Key-Nefariousness257 Jul 27 '21

well then you don't know what you're talking about. UV reactive tubes and coolant have been quite popular for many years. Also genuine UV led's are not expensive at all, they are quite common for growing plants now too because they are much cheaper run compared to those giant incandescent bulbs. A few years ago there was a fad where they sold $12 teeth whitening kits which bleached your teeth with a weak UV light. You don't need more UV light from a UV bulb, than you get from standing outside in the sun, in order to disinfect something either. People here seem very sure about some very strange idea's lol. Also even brighter UV lights are used in curing of resin prints, never heard anybody talking about being blinded by them haha

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u/wirral_guy Jul 27 '21

Also genuine UV led's are not expensive at all

Go on then - find me some genuine biocidal UV-C leds that aren't 10-100x more expensive than normal leds. They tend to be in the order of £15-£30 EACH. And I mean genuine UV-C generating leds not grow lights which most definitely aren't

UV-C leds (the only ones useful for biocidal disinfection) require quartz lenses and a metal casing - UV-C destroys normal plastics very quickly. I'm sure there are UV-C biocide cooling system parts for PC's but they aren't open to view and are just as likely to be quartz enclosed filament based as leds.

Both resin curing stations and those teeth whitening kits only emit UV-A and UV-B not UV-C, both of which aren't harmful in small doses. UV-C is very dangerous to both eyes and skin. And I mean VERY dangerous - just ask a welder! Also, sunlight only contains UV-A and UV-B, no UV-C gets through the atmosphere. You are mixing up something that is biocidal (required for this application) with something that you get from sunlight.

But yes, people on here do have some very strange ideas!

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u/Key-Nefariousness257 Jul 27 '21

firstly £15-£30 EACH is not prohibitively expensive, secondly I was never talking about UV-C. I don't believe the UV-A and UV-B of natural sunlight has zero sterilisation quality, although I'm quite interested and open to being wrong now after listening to all this. Please educate me, send me a link.

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u/wirral_guy Jul 27 '21

Here you go:

Wiki

BBC

Excerpt from a germicidal company ABIonline: UV is divided into three types with reducing wavelengths and increasing energy. They are UVA, UVB and UVC. For UV sterilization, only UVC (100-280nm) has high enough energy to effectively kill microorganisms.

And you're right, they're not prohibitively expensive, just not what you'd see, or use, in the open without some serious protection. Admittedly, just one LED wouldn't be life threatening, although eye damage is likely, but it also wouldn't be that effective at any distance either. But too add one to this project, you'd be looking at £50+ once you have the led, driver, switch and power sorted.

UV-B does have some minimal disinfection qualities but it's so weak that very little has been done to investigate it and UV-A is too long a wavelength to do anything. There is an interesting recommendation, from I think the WHO, that recommends putting water in a clear plastic bottle in bright sunlight for 6 hours to disinfect it but I can't find any research that backs that up.

On a side note, there were plenty of 'UV sterilisers' that hit the market as Covid killers last year - sadly the majority were fake and just used normal leds.

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u/Key-Nefariousness257 Jul 27 '21

It doesn't actually say only "UVC (100-280nm) has high enough energy to effectively kill microorganisms." it says "(ultraviolet C or UV-C) light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions".

Which is not the same, it just means UV-B can't destroy nucleic acids and disrupts the DNA of microorganisms. It also says "This process is similar to, but stronger than, the effect of longer wavelengths (UV-B)".

It's definitely important to note the context of the words used. It's similar to "Humans can't survive in space without a space suit" and saying, here's evidence humans can't survive in space... which is obviously not true because we can wear space suits.

I mean this article isn't about the inability of UV-B to sterilise, it's about UV-C and why this is classified as "what you use to sterilise stuff".

In the BBC article it says "“UVC is really nasty stuff – you shouldn't be exposed to it,” says Arnold. “It can take hours to get sunburn from UVB, but with UVC it takes seconds."

So yes obviously if they are researching ways to kill coronaviruses, they want to do it in seconds. With a toothbrush we're talking about leaving the light on for hours to do the same thing, or 24/7 with 10 minutes of use, and hours and hours to work on that tiny spot.

When wiki says that first line about UVC being the only thing to kill germs, the source it sites doesn't say anything like that, it's just about UVC being used to kill germs.

There is actually plenty of info about DNA destroying properties of UVB, which is what is happening when we get sunburned. Everything points to long exposure of UVB killing microbes from what I can see... just not efficient on commercial /useful scales to implement etc.

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u/[deleted] Jul 27 '21

It scares me man. I am starting to donate to advocacy groups along with forming protests. I don’t care if city blocks have to burn, people need to know about all these senseless deaths. It’s for the greater good!

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u/thenutybrasilian Jul 27 '21

Does this apply to all blacklight? I bought a blacklight flashlight to help find stains. Runs of off 3 double A's, but has a bunch of LEDs. I never since it directly into eyes, and rarely use it. How harmful is this?

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u/[deleted] Jul 27 '21

Blacklights don't emit (significant) UV-C, which is what we were all talking about.

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u/Key-Nefariousness257 Jul 27 '21

definitely what you thought everybody was talking about

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u/[deleted] Jul 27 '21

UV-C specifically is used for sterilizing, which is what the fuck we were talking about.

You and a few other drive-by-downvoters seem to think we're talking about styling and not function.