2012 iMac 27" Marks on Screen / Glass

I received mine around the same time, did this too when inspecting, and noticed the same thing. It didn't bother me, as I could only see it under those conditions, not in any way during normal use. Your hypothesis as to the cause is interesting. I thought it may just be residue from cleaning. Have you tried wiping it off from the outside to confirm it is on the inside?

Spots not visible on white background?

I returned one of the first bto 2012 21.5" in early December with what sounds like a similar display problem but I could more easily see the 1/16" diameter smudge centered around some larger problem when I had a white background.

I've a similar problem:


Looks worse as it is... there's also a second one, seems to be the glue!? I'm really happy with my iMac... I think I'll simple stick with it. What would you do?

edit: how can I downsize the picture?

You might be seeing artifacts from the metallic anti-reflective coating. I know that CRTs with the metallic anti-reflective coatings show all kinds of blotches when illuminated directly by a bright flashlight.

My new 2012 27" iMac's screen shows all kinds of vertical blotchy smears when illuminated by a close Maglight. They can be removed with brisk rubbing with a micro-fibre cloth, but since they are only visible with a bright flashlight held close to the screen, and otherwise invisible in normal ambient light I'm not bothering. I have found that it's very difficult to do a perfect cleaning of this screen, probaly due to the coating.

Be very careful when cleaning the screen, and use only a clean micro-fibre cloth. I was cleaning the screen with a previously used micro-fibre cloth which left a couple of scratches, an "Oh *****!" moment. The scratches were clearly visible in room light. Vigorous rubbing across the scratches with a brand new micro-fibre cloth removed the scratches. I figure that the anti-reflective coating was scratched and the rubbing with the clean cloth healed it.

Wow, there were smears, smudges, and dust. Distilled water, a moistened clean cotton terry cloth and a micro-fiber cloth later and . . . .

She's a perfect thing of beauty.

I just wiped pretty hard with a lens cloth and it came off.

FreemanW said:

Wow, there were smears, smudges, and dust. Distilled water, a moistened clean cotton terry cloth and a micro-fiber cloth later and . . . .

She's a perfect thing of beauty.

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Yes she is, but also a fingerprint magnet. Whenever my wife wants to point to something on a computer screen, she has to touch it. Then out comes the micro-fibre cloth. She thinks I'm too fussy.

drambuie said:

Yes she is, but also a fingerprint magnet. Whenever my wife wants to point to something on a computer screen, she has to touch it. Then out comes the micro-fibre cloth. She thinks I'm too fussy.

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My pet peeve! My parents, and especially my inlaws are terrible with this. they think every screen is a giant ipad! lol.

Re the smudges, ignore them. It is a byproduct of the manufacturing process of the AR coating. I have two Samsung TVs which do the same thing when illuminated by a flashlight. I returned one for it only to find ever set I inspected has it.

Be glad that while there is that side effect, reflections are almost non-existant. It's a thing of beauty. A shiny screen with no reflection. The best of both worlds!

drambuie said:

Yes she is, but also a fingerprint magnet. Whenever my wife wants to point to something on a computer screen, she has to touch it. Then out comes the micro-fibre cloth. She thinks I'm too fussy.

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QUOTED FOR TRUTH!!! I seriously lol'd!!!

Same here on a 27" Late-2012 iMac.





Spots beneath the lamination and cannot be rubbed off.