# How to block 100% of UV light?

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Hi all,

I'm looking for a setup to block 100% of UV light from windows. I understand that standard glass blocks the majority of UVB rays, but it lets UVA rays in, so I need to find a way to block those as well. Here's what I'm planning so far.

I will put Gila window film on the windows first. This film blocks around 98-99% of UV rays, or at least that's what it claims. I have read that window films often neglect to mention that the films can't block the upper spectrum of UVA rays (380-400 nm). I have confirmed this by asking the manufacturers of films for their performance data, so I will only rely on the film as an extra, not the main line of defense against UV.

I am going to purchase blackout fabric to make curtains. If this fabric is completely opaque and I cannot see any light, will this suffice for UVA protection? Can UV rays pass through the blackout fabric? I have also considered buying UPF 50+ fabric as well, but blackout seems better for this purpose (correct me if I'm wrong).

There's also one more problem associated with the blackout curtain method. How can I prevent light spillage from the sides of the curtains? I need a way to block the light that spills in from those areas (preferably a way that doesn't look awful). Some fitted window shades might work well for this purpose, but I'm really not sure so suggestions would be good.

I would greatly appreciate any advice, suggestions, or information anyone can offer. Thank you for taking the time to read and for any help!

Edited by epmarshall

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Do you need a method that allows you to remove it and then use the windows normally? If not, just spray paint them with some opaque color.

If you do, might I suggest the humble conspiracy theorist method of tin (aluminum) foil on the window?

Also, don't forget your interior lights - fluorescent lights do emit low levels of UV.

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Do you need a method that allows you to remove it and then use the windows normally? If not, just spray paint them with some opaque color.

If you do, might I suggest the humble conspiracy theorist method of tin (aluminum) foil on the window?

Also, don't forget your interior lights - fluorescent lights do emit low levels of UV.

Hi Greg and thanks for the suggestions. I do need to be able to remove whatever I put up, yes, since I am renting at the moment.

Haha, I might have to use the good old-fashioned conspiracy theorist look you mentioned. I take it that UV just can't pass through aluminum? Just trying to understand the reasons behind what I'm doing as well.

Oh right, thank you for mentioning the lighting in the room. I was also going to ask about interior lighting, but figured I would avoid asking too much at first. But now that you brought it up, do you know offhand if incandescent lights emit any UV? I'm also wondering about LED lighting, so if anyone has any info regarding interior lighting I'd appreciate that as well. I need to know which type of bulbs to get to avoid exposure.

Thanks for the help!

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I would look into articles on making a photography darkroom... there will be shops online that specialise in supplying the necessary stuff. Darkroom lights will also be minimal UV...film is very, undesirably, responsive to it.

Edited by StringJunky

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I would look into articles on making a photography darkroom... there will be shops online that specialise in supplying the necessary stuff.

I hadn't thought of that, thanks StringJunky! I will look into darkrooms.

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I hadn't thought of that, thanks StringJunky! I will look into darkrooms.

No probs.

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But now that you brought it up, do you know offhand if incandescent lights emit any UV? I'm also wondering about LED lighting, so if anyone has any info regarding interior lighting I'd appreciate that as well.

Incandescent bulbs do emit some UV, but not as much as compact fluorescent bulbs. Stay away from those if you can.

LEDs are probably your best bet, although long tube fluorescents are coated well enough usually to reduce UV to a minimum. I'd still go LED, since your options are broader. If you use an LED fixture that isn't trying to emulate an Edison-base bulb, you'll probably get a more efficient light with almost no UV at all.

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Incandescent bulbs do emit some UV, but not as much as compact fluorescent bulbs. Stay away from those if you can.

LEDs are probably your best bet, although long tube fluorescents are coated well enough usually to reduce UV to a minimum. I'd still go LED, since your options are broader. If you use an LED fixture that isn't trying to emulate an Edison-base bulb, you'll probably get a more efficient light with almost no UV at all.

LED head torches contain UV emitting diodes - white ones - I used to use mine to charge my artificial, luminous fishing baits with them. About 10 seconds would bring them to full brightness when placed directly next to the lens.

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Tin foil does block UV rays, assuming it's not unnaturally thin. I'd probably do a layer of foil, a piece of cardboard cut to fit for stiffness, and another layer of foil. That way you can pop it in and out of the window without worrying about tearing the foil.

From another thread on this very subject from SFN:

Cardboard (especially if it's black) would be a good way to block UV, but if you want to be really sure use aluminium foil.

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I will look into darkrooms.

You won't see much.

(See what I did there?)

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LED head torches contain UV emitting diodes - white ones - I used to use mine to charge my artificial, luminous fishing baits with them. About 10 seconds would bring them to full brightness when placed directly next to the lens.

That's the beauty of solid-state. You can make LEDs that have custom properties for the purpose they fulfill. I saw an LED array in IR for a CCTV camera, 48 LEDs arranged in a circle around the lens, for $3. Most bulbs and fixtures for the home and office aren't going to emit much UV, that's one of their selling points. #### Share this post ##### Link to post ##### Share on other sites That's the beauty of solid-state. You can make LEDs that have custom properties for the purpose they fulfill. I saw an LED array in IR for a CCTV camera, 48 LEDs arranged in a circle around the lens, for$3.

Most bulbs and fixtures for the home and office aren't going to emit much UV, that's one of their selling points.

Yes, I didn't think about the fact that their emissions are quite customisable. Not read up much on them TBH. That was just an anecdote of mine I remembered and I thought "Hmm, that's not right".

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Do we know yet exactly what this room is for? Why the need for blocking UV light, since it's not for a darkroom?

Vampires?

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What's the purpose?

I used to do lots of UV photolithography, we used rooms with no windows or wood over them. Filters over the lights (always weird walking back into normal lights after a few hours in the clean rooms). For storage/moving around we used metal boxes, aluminium a few mm thick. Even in the low UV rooms we used those boxes as the photoresist would expose with very very low levels of UV and you never knew when someone might use the lithography kit.

I'd either try and do it all in a metal box or use foil and cardboard closing the gaps with making and insulating tape.

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Tin foil does block UV rays, assuming it's not unnaturally thin. I'd probably do a layer of foil, a piece of cardboard cut to fit for stiffness, and another layer of foil. That way you can pop it in and out of the window without worrying about tearing the foil.

From another thread on this very subject from SFN:

Awesome, thanks for the explanation! I am thinking of making roller shades or panels of aluminum foil and cardboard as you just explained to put behind the curtains. I can remove them as needed that way. I'm just not sure on the specifics of how to attach it to the wall yet, but that is something I will research.

You won't see much.

(See what I did there?)

Haha, I definitely set myself up for that one.

Yes, I didn't think about the fact that their emissions are quite customisable. Not read up much on them TBH. That was just an anecdote of mine I remembered and I thought "Hmm, that's not right".

I'm glad that's cleared up, then. I always appreciate clarification on such things, so I appreciate you bringing it up.

Do we know yet exactly what this room is for? Why the need for blocking UV light, since it's not for a darkroom?

I'm just uv-proofing my entire apartment because I'm very sun-sensitive and I want to prevent aging from the sun. I don't want to wear sunscreen indoors when I'm not going out that day. I just want my apartment to be uv-free since I spend a lot of time at home and am kind of a hermit. I see no reason to take damage that I can prevent sort of thing, if that makes sense. A lot of people think I go overboard with it, so I didn't mention the reason upfront. Right now I live in a basement apartment with no windows save for one small one that I block in the bathroom, so it's not an issue. But May 1 I am moving to a high rise with many windows. Not to mention, in the fall I switch to the night schedule so I'll need to have things blacked out for day sleeping anyway.

Vampires?

Haha, pretty much. I've been called that before on numerous occasions.

What's the purpose?

I used to do lots of UV photolithography, we used rooms with no windows or wood over them. Filters over the lights (always weird walking back into normal lights after a few hours in the clean rooms). For storage/moving around we used metal boxes, aluminium a few mm thick. Even in the low UV rooms we used those boxes as the photoresist would expose with very very low levels of UV and you never knew when someone might use the lithography kit.

I'd either try and do it all in a metal box or use foil and cardboard closing the gaps with making and insulating tape.

Thanks for the input, Klaynos. This isn't for photography, but I still appreciate hearing the methods you used for your photolithography. It's interesting and may help me think of new ideas anyway.

Edited by epmarshall

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UV blocking windows are available- but expensive.

http://windowfilmcentre.co.uk/index.php/commericalfilm

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I'd just use some kind of blackout curtain like hotels use, along with your normal curtains. Then use LED bulbs and fixtures that advertise little to no UV. You don't have to go too crazy with this to protect your skin. This is probably cheapest.

It will also have the advantage of protecting any colors in cloth from fading due to UV light.

You might want to check to see how much it would cost to use a transparent UV film on your windows. They make them so they don't even have a tint if you don't want it. This way you get light and sun without the harmful part of the spectrum. You can also get daylight harvesting controls for your LED lighting so they dim when the sun is out, and come up to full as clouds or dusk change the ambient light.

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Tin foil does block UV rays, assuming it's not unnaturally thin. I'd probably do a layer of foil, a piece of cardboard cut to fit for stiffness, and another layer of foil. That way you can pop it in and out of the window without worrying about tearing the foil.

Depending how fussy you are, this might need some sort of soft/squishy edging to make sure nothing leaks around the outside.

Haha, pretty much. I've been called that before on numerous occasions.

Not sure if this is relevant but I heard a radio program a while ago about a woman who developed extreme photosensitivity. It started out as being irritated by sunlight and fluorescents and then progressed to pretty much any source of light. This seems to have been triggered by stress. It pretty much destroyed her life: she was unable to work or socialize. But she did eventually and very slowly recover, to some degree at least.

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UV blocking windows are available- but expensive.

http://windowfilmcentre.co.uk/index.php/commericalfilm

I am renting at the moment, so not really a possibility right now.Thanks for at least explaining the option, though.

Depending how fussy you are, this might need some sort of soft/squishy edging to make sure nothing leaks around the outside.

Not sure if this is relevant but I heard a radio program a while ago about a woman who developed extreme photosensitivity. It started out as being irritated by sunlight and fluorescents and then progressed to pretty much any source of light. This seems to have been triggered by stress. It pretty much destroyed her life: she was unable to work or socialize. But she did eventually and very slowly recover, to some degree at least.

Hm, that's interesting. So was it biological in nature or just became a phobia?

And you're right I'll need to deal with the edges where light spills in. Either that or get some window roller blinds that have sides.

I'd just use some kind of blackout curtain like hotels use, along with your normal curtains. Then use LED bulbs and fixtures that advertise little to no UV. You don't have to go too crazy with this to protect your skin. This is probably cheapest.

It will also have the advantage of protecting any colors in cloth from fading due to UV light.

You might want to check to see how much it would cost to use a transparent UV film on your windows. They make them so they don't even have a tint if you don't want it. This way you get light and sun without the harmful part of the spectrum. You can also get daylight harvesting controls for your LED lighting so they dim when the sun is out, and come up to full as clouds or dusk change the ambient light.

Thanks for all the info, Phi for All! So LEDS are best to use, then? Also another thought I had, it might sound stupid but what about LED Christmas lights? I was thinking of having some up in the apartment year round. I am just asking to make sure because I know those are widespread so I'm not sure all the places that manufacture them will use the correct filters. Will those most likely be safe or do I need to find ones that advertise little to no UV?

Thanks again to everyone, I appreciate all the help!

Edited by epmarshall

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So LEDS are best to use, then? Also another thought I had, it might sound stupid but what about LED Christmas lights? I was thinking of having some up in the apartment year round. I am just asking to make sure because I know those are widespread so I'm not sure all the places that manufacture them will use the correct filters. Will those most likely be safe or do I need to find ones that advertise little to no UV?

Christmas lights might not be engineered for low/no UV, since that's not their main purpose. I would go with some standard LED bulbs or fixtures where low/no UV is one of the primary concerns. Bulbs are going to fit in the old Edison-base fixtures. If you can, I recommend taking advantage of a fully-integrated LED fixture, one that isn't trying to emulate an incandescent or fluorescent lamp. These are going to give you the best optics for the energy, and while they might be a bit more expensive, they make up for it in longevity and low-maintenance. Maybe floor lamps, so you can move them around easier, without making them a part of the apartment?

Color temperature might be a concern for you, since you're sort of spelunking in this space. Warmer temps (2700K-3500K) are cozier and help you wind down after a day spent out in the world. Cooler color temps (4000-6500K) are bluer and give you more of an outdoor "sunny" effect, which doesn't really encourage relaxation, but it's great for focus.

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just a thought- people typically live something like 30,000 days and during that time they rack up some level of damage.

If you reduced the exposure 100 fold then, over the whole of your life you would get something like a year's worth of exposure during you whole life.

Even a 10 fold reduction would mean you only got 10 years worth- or thereabouts.

Well, most 10 year olds don't look sun damaged.

So it's clear that 10 year's worth of sun isn't an issue- so there's no need to reduce exposure by more than about 10 fold.

An ordinary window will do that.

So the whole idea is pretty much pointless.

You only need to worry about sun damage if you are outside- and that's what sun cream is for.

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Hm, that's interesting. So was it biological in nature or just became a phobia?

It definitely wasn't just a phobia; she had severe physical symptoms. But as far as I remember, they were unable to find any "physical" cause so it was, presumably, a conversion disorder (i.e. psychologically based).

So the whole idea is pretty much pointless.

You only need to worry about sun damage if you are outside- and that's what sun cream is for.

There are a quite a few disorders which can produce unusual sensitivity to light/UV. Some of these do require people to avoid UV almost completely, and in some cases be in complete darkness for a recovery period. Some, such as xeroderma pigmentosum, can be fatal.

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It definitely wasn't just a phobia; she had severe physical symptoms. But as far as I remember, they were unable to find any "physical" cause so it was, presumably, a conversion disorder (i.e. psychologically based).

There are a quite a few disorders which can produce unusual sensitivity to light/UV. Some of these do require people to avoid UV almost completely, and in some cases be in complete darkness for a recovery period. Some, such as xeroderma pigmentosum, can be fatal.

I imagine, also, some people have over-sensitivity problems with their eyes or visual system when exposed to it.

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Christmas lights might not be engineered for low/no UV, since that's not their main purpose. I would go with some standard LED bulbs or fixtures where low/no UV is one of the primary concerns. Bulbs are going to fit in the old Edison-base fixtures. If you can, I recommend taking advantage of a fully-integrated LED fixture, one that isn't trying to emulate an incandescent or fluorescent lamp. These are going to give you the best optics for the energy, and while they might be a bit more expensive, they make up for it in longevity and low-maintenance. Maybe floor lamps, so you can move them around easier, without making them a part of the apartment?

Color temperature might be a concern for you, since you're sort of spelunking in this space. Warmer temps (2700K-3500K) are cozier and help you wind down after a day spent out in the world. Cooler color temps (4000-6500K) are bluer and give you more of an outdoor "sunny" effect, which doesn't really encourage relaxation, but it's great for focus.

That's interesting since I usually picture blue as the relaxation color. Thanks for sharing! It's good to consider how this will affect the whole look of the apartment.

Floor lamps are definitely something to consider. Also, excuse the ignorance since I know very little about light fixtures, but how do I determine whether an LED light is in a fully integrated LED fixture rather than trying to emulate a fluorescent or incandescent model?

Thank you again, Phi for All!

It definitely wasn't just a phobia; she had severe physical symptoms. But as far as I remember, they were unable to find any "physical" cause so it was, presumably, a conversion disorder (i.e. psychologically based).

There are a quite a few disorders which can produce unusual sensitivity to light/UV. Some of these do require people to avoid UV almost completely, and in some cases be in complete darkness for a recovery period. Some, such as xeroderma pigmentosum, can be fatal.

Yes, agreed. I have heard of xeroderma pigmentosum and they are forced to realize the importance of blocking out all UV light they can since they can't repair their skin after receiving damage as normal people can.

just a thought- people typically live something like 30,000 days and during that time they rack up some level of damage.

If you reduced the exposure 100 fold then, over the whole of your life you would get something like a year's worth of exposure during you whole life.

Even a 10 fold reduction would mean you only got 10 years worth- or thereabouts.

Well, most 10 year olds don't look sun damaged.

So it's clear that 10 year's worth of sun isn't an issue- so there's no need to reduce exposure by more than about 10 fold.

An ordinary window will do that.

So the whole idea is pretty much pointless.

You only need to worry about sun damage if you are outside- and that's what sun cream is for.

Every bit of sun damage does add up, that's been scientifically proven. It doesn't matter if it comes from a day at the beach or sitting in front of a window. When you put a 10 year old under one of the UV lights that dermatologists use to show UV damage, you see discolorations and damage already. This damage doesn't show up until later on in life, but damage accrued at this age does matter and show up at some point. The figure I've commonly read is that damage you accrue shows up about 10 years later. So if you tanned as a teenager, you'll start seeing signs of it in your 20s, etc.

It's definitely not pointless to me anyway and I'd like to do everything I can to preserve myself and 10 years seems like a big deal. I still appreciate the input and dissenting opinion, though.

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