Yes agree, difficult to control all variables but I tried as much as possible to avoid them.
Here are more details about what I did :
*I used a lamp wich has a very narrow wave light in UV visible.
*the light used was a laser pointer which has a specific wave frequency ( because is a laser )
*I tested it in an almost dark chamber - no direct light from sun and other sources.
*I made the test in a cartoon box to avoid as much as possible any other type of light interference
*I used 5 types of resin: loon, deer creek, solarez, bug bond and resin used in professional UV printing. All behaved almost identically.
*glasses used where Orvis, Zeiss, Smith, Mouche Devaux France, cheap no-name Chinese glasses and some Swedish glasses in: yellow, green, brown, gray. With plastic and glass lenses. Some of them new some of them from friends.
Of course that the resins can react on a larger spectrum of light even in non UV light. But in my room was almost dark and I consider that I took out all other radiations from my equation. For coating I used laser light which is a clear radiation in UV spectrum
* Without polarized eyeglasses the resins went harder in a few sec.
*With eyeglasses on the resins went almost hard ( a thin layer ) but not completely in over 30sec.
*dark colored are more protective compared with light colored, is obvious that the light absorption is higher if we talk about dark colored glasses and less for glasses with light colored lenses.
* the polarized eyeglasses protect against UV but far from declared 100%.
*glass lenses are better than plastic ones because the plastic is easy to be deformed and will present spherical aberration which will give you headache in time.
I had a chat these days with a professor from our local University and he told me that is not such thing: lenses or glasses capable to offer 100% protection. Even ordinary glass provides UV protection but 100% UV protective glass is not possible.
Brands like Zeiss, Varivas, Talex, Tiemco, do not tell to anybody that they glasses provides 100% UV protection ( some of them 90 or 99 but not 100% )
My Final Conclusion:
In the end: cheap Chinese glasses are good and protect your eyesight enough in the same way like those expensive do/ But because they do not have complicate and super durable anti scratch layers is better to change them at 2 or 3 years. The most important thing is to be sure that they do not have deformations and diopters which is very easy to test . Then 2 or 3 pairs are a must, light colored for cloudy days and darker for super sunny days.