Glass or plastic? That is the question manufacturers are faced with when designing lenses for lighting solutions. It is an important consideration and will have implications on how the solution transmits light, resists impact, and combats discoloration. Plastics are gaining wider acceptance in outdoor and industrial lighting applications when LEDs are being used. But switching to polycarbonate materials comes with disadvantages that render them inferior to glass lenses. Here is what should be known about glass and plastic lenses before making an investment in the technologies.
One of the most important factors in choosing between glass and plastic lenses is clarity. Plastics will develop a haze over time, with studies revealing polycarbonate can break down by 20% in 3-4 years even without exposure to UV radiation — a common source of degradation. When it comes to light transmission, borosilicate glass transmits 92% of the lumens, while new polycarbonate transmits only 85%. This number declines even further as the plastic is exposed to UV, heat, and age. Furthermore, plastics suffer from unsightly discoloration issues which results in less light output and raises the probability of premature product failure. Borosilicate glass does not discolor when exposed to UV light, heat, and harsh environmental conditions.
Plastics have higher impact ratings than glass when comparing similar thickness. However, most plastic lenses are not even 1/8″ thick on billboard lights, less than what would be used in a glass construction. The difference in mass reduces the strength advantage of plastic, the one area where it had a leg up on glass. And when it comes to surface hardness, glass is the runaway winner, translating into a more durable lighting solution that resists scratches and requires fewer maintenance interventions.
When comparing the two materials, it is essential to understand how glass and plastics scatter light. Glass offers more precise light distribution than plastics, making it the perfect solution for spaces that need targeted lighting. For example, the ideal streetlight will illuminate the road and not the area behind it where a home or business may be located. A similar scenario is a sports field where a high level of light is desired on specific parts of the field, and lower levels off of it.
Those in the market for outdoor or industrial lighting solutions should understand the advantages glass lenses hold over those made of plastic. High-performance glass lenses maximize fixture efficiency and efficacy while providing mechanical strength and long lasting durability. Global Tech LED is a LED lighting solution manufacturing company specializing in LED retrofit kits and new fixtures for commercial and industrial lighting applications.
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