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Name:  Bosekarthik
Status:  other
Age:  20s
Location: N/A
Country: N/A
Date: 2000-2001

I find some road signals sign boards glow in the dark or reflect the light (in glowing style)...

1. is this chemicals different from self luminous materials(the chemicals like like radium which glow in the dark)?

2. will they lose their property over the period of time... if so in how many months?

3. can u explain the chemistry behind that chemicals( that is why they reflect

much light so that they appear to glow)? 4. can u tell me some names of the chemical compound which exhibits this property?

There are three basic retroreflective technologies: corner cube, bead, and parabolic.

Corner cubes are just what they sound like. Stimsonite used to produce them, but they have been taken over by Avery. They have a metallic backing shaped like the corner of a cube. Very long lasting, but there are some overglow problems when used for lettering. 3M does some, also.

Bead technology is also used, 3M is one of many manufactures. This is used in lane markings and crosswalks. They wear out in a few months and need to be redone sooner than the paint that they stick to. When used as signage, the overglow problem is reduced, and can last for years without the need for replacement. On signs, they are generally plastic encased. The beads are plastic.

Illuminite corporation does the parabolic reflectors, which has many clothing applications, but very few traffic applications.

The keywords for search include: corner cube reflector, retroreflection

---Nathan A. Unterman

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