I have just purchased a long mirror & on hanging it (horizontally) i find It distorts the image fat & thin . How do i correct this please. I think it is either concave or convex

  • Get a new mirror?
    – iLikeDirt
    Jul 22 '14 at 19:00
  • How is this hung? In a frame, or directly attached to the wall?
    – alt
    Jul 22 '14 at 19:11
  • take it back to the shop where you bought it. Is it a plastic mirror?
    – hookenz
    Jul 23 '14 at 3:39

If it's very long, I'd suspect that it's being physically distorted during the installation process since the glass itself is flexible enough to distort the image without breaking first. To correct it, you need to make sure that the mirror is as straight as possible - use shims.

If it's along a wall, the mirror may be following the contours of a slightly uneven wall. You can shim the back of the mirror in the hollow spots to correct this. Masking tape (ideally the blue kind to protect the mirror) can be used in the low spots to build up sufficient support for the glass. Thicker shims can be used if you find the hollow spots to be very thick.

It's it's in a frame of some sort, either the frame is not straight, or it is sagging/distorting too, or (if the glass is sufficiently loose int he frame) the mirror itself is just distorting as above. The approach is basically the same - shim the spots that you need to push forward.

  • Many thanks for that suggestion I will leave it hung for a week then attempt It . Thanks again you've been very helpful
    – M Easter
    Jul 23 '14 at 9:33
  • no problem. I was just thinking, in the interest of preventing the backside of the mirror from getting damaged by the tape (either from adhesion or possible acidic reaction with the adhesive)s, you could put the adhesive side of the tape against the wall/frame, whatever the case may be. Even better than blue masking tape would be photo-quality acid-free tape... at least for the layer that contacts the mirror. It may be worth investing in that stuff (can get from any craft store, amazon, etc) if you've already invested in a very large mirror. Good luck!
    – aaron
    Jul 23 '14 at 12:25

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