On Tuesday, April 23, 2019 at 12:48:04 PM UTC-7, Bob Kuykendall wrote:
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.

That matches my experience. It basically depends on the glider. To know for sure, you have to get a meter and measure your own canopy.