KrackerG Posted February 17, 2004 Share Posted February 17, 2004 During my mission in finding the correct glass needed for my 20” CSL 70w MH, I obtained a reasonable amount of knowledge about glass and UV rays… and even some basics about how light works. However, I’m most definitely NOT an expert in ultraviolet, lights, rays, electrical, or glass or anything that falls in between. But some of the info below may be of use to you… UV LIGHT Ultraviolet light, or UV is present in EVERY single light source…the sun, a lamp, a window or skylights, fluorescent tubes, and halogen bulbs as well. UV rays are more commonly known for wrinkles and sunburn on your skin but also can do some serious damage to it’s surroundings causing fading, yellowing and aging. It’s inherent to every light source…however all manufactures coat their bulbs to protect from these rays…except MH HQI bulbs….Ok??! UV GLASS Now for UV blocking glass, there are a few various types but all of which, filters out over 97% of damaging UV light rays. Your mid-grade UV filter glass has a spectrum cutoff slope set gradual so it allows for a small amount of UV transmission in the 300nm to 400nm spectrum region. From there, all that gets blocked is light transmission below the 300-400nm which is basically blocking the whole UV region and allowing the transmission of the visible light spectrum beyond the 400nm and into near infrared. The more expensive UV glasses differs in overall clarity but has an almost vertical ascent around 400nm, going from almost zero just before 400nm to 90 percent just beyond 400nm. It can also be done tempered for strength and made of pyrex-based material so it can deal with a reasonable amount of heat…. Link to comment
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