Mailing List lml@lancaironline.net Message #70548
From: Kevin Stallard <kevin@arilabs.net>
Sender: <marv@lancaironline.net>
Subject: RE: [LML] Re: UV & IR Filtering Film on Acrylic Windows
Date: Mon, 13 Oct 2014 07:09:59 -0400
To: <lml@lancaironline.net>
According to Wikipedia, sunburns are caused by UV radiation in between the UVA and UVB bands.  You can get burned under UVA, but it much harder to do so than under the effects of UVB.  UVB is responsible for creating Vitamin D, but can also damage DNA ( I was wondering where that third arm was coming from, I wonder if the FAA has a medical exemption for it )

UVA is UV radiation in wavelengths between 400 or 315 nm (not absorbed by the atmosphere), UVB is between 315 and 280 nm (mostly absorbed by the atmosphere).   They have a nice graph that seems to show most of the skin burning wavelengths between 300 and 325-330 nm.

Also according to Wikipedia, Poly(methyl methacrylate) (or PMMA, aka acrylic and plexiglas) absorb UV wavelengths at around 300-315 nm, which happens to be the same was window glass.  Some manufacturers add things to it to do UV absorption from 400 nm.

Window glass (and PMMA) absorbs most of, if not all UVB.  It absorbs about 75% of UVA, mostly near the 315 nm area if I understand this correctly.  These additives appear to grab the rest above 315 nm.

So, it appears you can indeed get tan or some burning of the skin under glass, but it is very reduced compared to being out in the open.  But it also explains why my glasses wouldn't darken while in the airplane.

Kevin
 

________________________________________
From: Lancair Mailing List [lml@lancaironline.net] On Behalf Of Thorn, Valin B. (JSC-VA411) [valin.b.thorn@nasa.gov]
Sent: Thursday, October 09, 2014 5:11 AM
To: Lancair Mailing List
Subject: [LML] Re: UV & IR Filtering Film on Acrylic Windows

Hi Doug,

Of course, the UV protection is for passenger skin and to protect the materials from rapid break down.  I’d rather not have to put sun screen on to go flying.   The IR is to limit the greenhouse heating effect.  The canopy shades seem a little clunky to me – but, haven’t ruled them out if this doesn’t work…

I haven’t heard back from Kim yet on what filtering properties the acrylic has.

Thanks,

Valin



From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Douglas Brunner
Sent: Wednesday, October 08, 2014 5:24 AM
To: Lancair Mailing List
Subject: [LML] Re: UV & IR Filtering Film on Acrylic Windows

Valin,

Why do you want to do this?  Not a criticism, just a question.

What I have found to be extremely valuable is a canopy shade that allows me to control the amount sun that comes in.

D. Brunner



From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Thorn, Valin B. (JSC-VA411)
Sent: Tuesday, October 07, 2014 4:47 PM
To: Lancair Mailing List
Subject: [LML] UV & IR Filtering Film on Acrylic Windows

Hello,

We’re looking at applying ultraviolet and infrared filtering films on our Legacy’s canopy.  Not looking to darken it since the canopy has some tinting in it already -- though, looking to filter as much UV and IR as possible.  There are several products from 3M, Llumar, and others with these properties used on cars and glass windows every day.

Has anyone one applied any window tinting or other films to their acrylic windows?  How did it work out or not?

Kim at Lancair is checking with their acrylic window vendor to see what UV and IR filtering properties their acrylic windows already have.

Thanks,

Valin Thorn
Legacy Project
Colorado

BTW, Paul and Marv, this is an example of a question that applies to all Lancair aircraft types.  We could use a category on Lancairtalk.net for these kinds of general topics, questions.




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