LED seal for a dedomed LED

Has anyone done any testing to see if it affects lumen or throw?

I’ve read it can provide some “protection” after a dedome.

Following....

Some guys say it is good...

Or maybe Liquid Glass Shield
http://youtu.be/xufAQ8SHLxc

Anyone?

https://www.norlandprod.com/adhesiveindex2.html

Probably the best product the public can buy.

Looking at product list and NOA89 mentions using it as a coating.