Sun Protection While Soaring - UPF 50+ Clothing

On Sunday, April 21, 2019 at 8:46:13 AM UTC-5, Richard DalCanto wrote:
On Sunday, April 21, 2019 at 1:38:36 AM UTC-6, Tango Whisky wrote:
Sun screen helps you to avoid superficial sun burn, but it doesn't do anything against UVA and the subsequent skin cancer. The only thing which helps against skin cancer is clothing.

That is not correct. Quality sunscreen protects against UVA and UVB.

There is another factor here making the issue even more complicated. It seems there are two basic types of sun screen, chemical and mineral. There is considerable debate as to if some of the ingredients in the chemical types may cause other health issues. There is a lot of info on line about this. I started using a mineral type this season, which can be hard to find. It is white and stays that way making you look like a ghost.

Terry

This is a topic with multiple facets. If you are looking for more info on suncsreens, here's what appears to me to be a reasonable discussion on their effectiveness and some possible risks: https://www.choice.com.au/health-and...ides/sunscreen

From my reading, Acrylic, which I think most/all canopies are made of can be made to block UV with additives, but in its pure form it does not. So it depends on the specifications of the acrylic that was used in the manufacture of your canopy. I found one reference that suggests Mecaplex, who make canopies for many gliders, use an acrylic that "blocks 95% of UV": https://www.dg-flugzeugbau.de/en/lib...nopy-dg-glider

If anyone has a spec sheet for the acrylic used in their canopy, that would be interesting data.

I was talking recently to Ian Linke, who makes canopies here on Australia, he told me he can get two types of Perspex, one that is normal and one that blocks UV, however the UV block is considerably more expensive, about 3 x the cost.

My understanding is that Plexiglass = Perspex = Lucite = PMMA = poly-methyl-methacrylate = pure acrylic

Here's a transmission curve for pure acrylic (PMMA) vs UV-transmitting Acrylic: https://www.gsoptics.com/transmission-curves/

It seems that you have to work hard to get an acrylic that does not block all of UV-B and almost all of UV-B

I started using a mineral type this season, which can be hard to find. It is white and stays that way making you look like a ghost.

The mineral suncreens are zinc oxide and titanium oxide nanoparticles, the "white" ingredients of white paint, and the oldest sunscreens. They scatter UV instead of absorbing it like the chemical ones do. So using this is basically painting your skin white. If you can see skin, it's not enough .. Or they add enough other ingredients (oils, etc) that absorb the rest of the UV, so you're back to chemical absorption.

On Saturday, 20 April 2019 02:18:13 UTC-4, David Hirst wrote:
....SNIP...
If you think of a glider canopy as an SPF100 layer, you won't be far off.

....SNIP....
As previously stated, your biggest danger is in hanging around on a sunny airfield,
....SNIP...
DH
TX

Is that really the case David? It is the first time I have heard about this..
I recall being told that the plexiglass was doing nothing to protect against
UVA & UVB. This is still what I preach at the X-country lecture that I give at
my club. If what you claim it true, I'd have to change my storyline and workflow.

Having been more than once incommodated by an aweful mix of sweat and solar cream in my eyes while airborne, I would really like to get away from "buttering" up before a flight. I can see the point of protecting our skin while running around the airfield but right now my routine seem reversed: I wait
until the last minute to layer the sunscreen on my face, hands, neck and ears just as I climb in the cockpit for my XC flight

Can anybody challenge David's claim here?

Can anybody challenge David's claim here?

See the posts above by:
who measured the reduction with a meter
David Hurst who analyzed a transmission curve
Bret (me), who posted transmission curves

Plexiglass blocks UVB and most of UVA. David said only 17% of UVA is transmitted by 2mm plexiglass. My canopy is 4mm thick, twice as thick, and the transmission dies off exponentially with thickness so roughly (0.17)^2 = ..03 = 3% of UVA is transmitted, which matches what measured: very little is transmitted.

Correction: my canopy is 3 mm thick, so I'd guess about 10% of UVA is transmitted.

On Sunday, April 21, 2019 at 9:19:16 PM UTC-7, Bret Hess wrote:

It seems that you have to work hard to get an acrylic that does not block all of UV-B and almost all of UV-B

I'm told that not all acrylic is created equal. Years ago I sold an old free-blown glider canopy transparency to someone with an LS-1 who had lost their original canopy. Later, they took UV measurements and found that the Mecaplex fixed forward canopy blocked a lot more UV than the hinged canopy section they made using the transparency I'd sent. I don't recall whether that was UV-A or UV-B, though.

--Bob K.

He educated me that UV does not transits mediums to any concerning levels

Can anybody challenge David's claim here?

Lab science vs my real life experience: I get a tan very fast once I start soaring each season. If I don't use my sunscreen cream (factor 30), after few hours of gliding my face, neck and arms are red. And I also have been explaining to others how plexi transmits UV, unlike glass, except for special quartz glass used in the lamps/bulbs so that people can get the desired tan and pay for it. So what I'm reading posted above turns everything upside down - not so much my scientific knowledge which I have none, but my practical life experience.