Weird Blotch on my iMac Display


macrumors newbie
Original poster
Mar 30, 2014
I've already went ahead and made a genius appointment for this week, but would anybody mind taking a look at this blotch on the bottom left corner of my 27" iMac screen and give me their take on what it can be? I took the photo with the screen showing a pure white background




macrumors member
Jan 6, 2004
Humidity perhaps that got between the glass and the LCD? Looks like the glass will need to come off and them some iKlear cleaner applied. Not sure if this is a depot repair where they send it out (usually to the Texas center) or if they can do it overnight at the store. I would guess a depot repair.


macrumors 6502a
Jul 31, 2007
Had the exact same thing happen to me on my 2010 iMac. about a year and a half ago.

It's like a weird dirty spot on the LCD that suddently appear.

Went to the Genius Bar and the genius told me that this is a recurrent problem with these 27' displays and that Apple extended the warranty for this particular problem. Had Applecare at the time, but he told me that they would have swapped the lcd screen for free anyway.

So you should be fine and it should be covered.


macrumors 6502
Feb 28, 2010
If your iMac is pre-2012 it's probably dust between the LED panel and the backlight.


macrumors regular
Mar 9, 2012
Have just discovered the same issue on my late 2012 27" iMac also. Just happened to notice it when opening Safari full screen, not often there is anything with a white background in that lower left corner.

Lots (& lots) of comments here about the issue.

In the Czech Republic, the law mandates a full two year warranty on electronics which in this situation is useful as you cannot buy a machine with AppleCare here and my machine is now over a year old. My two years will be up in December of this year so I think I'll wait until closer to then before contacting Apple to discuss repair/replacement.

Is it likely that the smudge will get steadily worse? I haven't read through all 83 pages of the discussion on the Apple Support pages.


macrumors regular
Apr 12, 2011
My 27in just got the same smudge/blotch in the lower part of the screen. Purchased brand new from Apple 3/2013 and hopefully this issue is covered under the AppleCare I'd purchased. I didn't notice until I was viewing a website that had an all white background and the blotch really stood out. I wonder what happened to cause this and if they replace the screen if the issue can reoccur.