Mirrors intensifying heat from sun

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I saw a post that I'd like to try. It was broken mirror pieces (4" max. size) used on a privacy outdoor fence to create a design (i.e., starburst, swirls, etc.). One reader said a similar one created a fire because of the heat created by the reflecting mirror. Can a design like this create enough heat to start a fire? I know glass can be used to intensify the suns rays shining through it, but if it can't shine through but only reflect the sun, can the reflection in this scenario cause a fire?
  7 answers
  • Debs Debs on Mar 17, 2016
    Perhaps using good placement of the mirror pieces so they do not reflect the direct rays from the sun would be ok to do.
  • Patricia Bell Patricia Bell on Mar 17, 2016
    I believe that it could help start a fire from the reflective ability. It only takes one time for the conditions to be right for this to happen. Better to be safe than sorry. I love the way it looks!
  • Irene Irene on Mar 17, 2016
    Sounds like the mirrors involved in these disasters were magnifying mirrors (as in the Google story). It wasn't the vanity mirror, it was magnifying mirror on the top of the vanity. In another case it was glass jugs filled with water that were set on the window sill, which magnified the sun's rays. Still not sure a plain mirror reflection would cause increased heat to start a fire in normal circumstances.
  • MN Mom MN Mom on Mar 17, 2016
    I'd hesitate to use mirror pieces not just for fear of starting a fire but also of blinding anyone who happened to be in the way! Could you use colored glass or mosaic tile instead?
  • Duv310660 Duv310660 on Mar 18, 2016
    If your glass mirror is thin and the pieces are broken up and mounted with separation, there is less chance of a heat build up under the pieces. If you have a concern, mount a foot square mirror tile to wood and place it where you are planning your structure. If that does not get too hot, then I think you are safe with smaller spaced pieces. Remember that sunshine is the most intense at solar noon, and that vertically-mounted pieces of mirror will get less direct sun at this time.
  • Susan Ziegler Susan Ziegler on Apr 29, 2016
    I understand that you can start a fire with a mirror and sun aimed onto combustible material. (scouts) I placed mirror outside and birds crashed into it.
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