Greyish Smudge marks behind the glass screen.

I too have a problem with my new 27" iMac late 2012. Grey smudges appears on the bottom left and right corner of my LCD panel in 3-4 months. What to do please help and suggest.

@Abhishek ShastriI just had my late 2012 new imac replaced for screen issues. They'll send you a new one and you gotta move everything to the new one and ship back the old one.

I have a mid 2011 27" imac and just noticed that when I have a light screen there are what look like snake stains on the left side of the screen. The right has the same althought they are more faint.

I just noticed this today and have not seen it before so it must have just appeared.

They look almost like water stains. You can really see them when you boot up the imac and the mac logo appears with that white screen (before it boots to your desktop)

What is causing this? Will they replace?

I own an Imac 27 I7 of 2011 still under warranty.
6 months ago I replaced the display because he had yellow undertones.
A few days ago I noticed that startup, and on white and gray backgrounds there are three vertical smear that can not be seen but only the front side.
I contacted the assistance hoping to solve the problem.
In addition, the sensor for adjusting the brightness sometimes it works and sometimes not.
I'm really amazed that lately Apple has lost quality.
Greetings.

Messed up! You should have Apple fix or replace part(s), especially if under warranty.

In your opinion, what is it?
Backlight?
Thank you.
I have already contacted the assistance.

I have no idea what this is. It is not the same issue that has been discussed here in this subject "Grey Smudge marks behind the glass screen". This is something else. I hope Apple makes it right for you.

i also had this problem, basically it looks like water sandwiched between 2 peices of glass.

I had the screen replace less than a month ago, but i noticed new marks on the screen once again.

Spoke to Apple, they are giving me all kinds of nonsense about the problem being environmental.

I have Apple Care and told them to do an onsite repair. They wanted to bring the machine in to "evaluate" the problem. To which i told them to do an onsite repair.....period.

I told them when the tech comes, to bring a replacement in case he determines that it needs to be replaced. But was told that they need to evaluate if the problem is environmental.

***!!!!! In less than a month, the problem shows up and it is environmental??? What about the poor quality control of these screens, coming out of the factory!!!

Its also a waste of time for the tech to come out 2 times, one to evaluate the problem and then come back again to actually replace the screen.

This is not the first time this has happened to me so I don't know why Apple isn't doing something to solve this problem. It is clearly a manufacturing issue.

Where i am it is in the tropics, there is going to be humidity. Basically, they want all iMac users who encounter this problem to put the machine in a clean room that is temperature controlled, air scrubbed and we have to wear anti static suits.

Common Apple you need to get your **** togethter.

I am not very happy in the way I was talked down to by the Apple care specialist.

So I just got the dreaded grey smoke/flame looking problem on my 27" Apple Cinema Display (non-thunderbolt version) that it seems like a lot of people have here:

What irritates me the most is that this display was PERFECT. It literally took me months and hundreds of dollars trying around the Tennessee state looking for a display that didn't have dust behind the glass and/or dead pixels and after like the 6th one I finally found this one and bought it off someone a few years back.

I recently moved to Hawaii and I'm thinking the monitor getting shipped from an airplane made this happen due to the pressure/humidity differences since I think it started to appear shortly after I got here.

So from me reading this topic it seems like I only have 2 choices. Either call apple or bring it into the apple store. I'm not even the original owner of this monitor so I don't even have a purchase receipt plus of course it isn't under apple care or anything. Do I literally just need to beg to death for a new monitor via phone call or the geek bar? What are my chances?

I had a similar problem so I went to the genius bar in the Apple store in Cardiff (Wales) and they sorted it out I had my Mac back in 2 days I had 2 months left on my Apple care thank God the customer service was absolutely first class and this is what they did to correct the problem

Warranty Status: Protection Plan(A)

Model: IMAC (21.5-INCH, MID 2010)

Date of Purchase: 10-Oct-10

Serial No:

Parts and Services

Item Number	Description	Price	Amount Due
661-5799	LCD Panel, 21.5", with LED Backlight Board	£ 275.00	£ 0.00
S1490LL/A	Hardware Repair Labor	£ 24.00	£ 0.00
VAT		£ 0.00
Total		£ 299.00	£ 0.00

Hello, I have replaced the display.
And 'the second in 6 months.
I also hope and there I think I have solved the problem.
greetings

I have the same problem. My screen looks similar to Seyumi's screen. I own a 2011 27inch Imac. I read somewhere that if you turn down your brightness about half way or turn off your computer for a long period of time, the water like stain should go away. I tried it and bam! The grey stain was gone. It does suck though not being able to have my computer on 24 hours a day or have the brightness up all of the way, but whatever it keeps me away from applecare.

Same problem on my 21.5 inch iMac (MC309LL/A) - dark spots all across the top of the screen.

Took it in to the local Genius Bar today and was told that this is not a "known issue" with this model and it will not be a covered repair since my warranty recently expired.

Called Apple Support (800-275-2273) and was told the same thing. They also indicated my one-year warranty expired on 04/30/2013 despite the fact that I purchased the computer on 06/28/2012.

Not too impressed with Apple's customer service right now...

@Chris Adrian .. Oh really? You eliminate your smudged display problem simply by turning it off? How long did you turn your iMac off until the marks disappear?

Does it appeared again though after some time?

Looks like LCD panel de-lamination, which would require replacing the LCD panel. This happens to LCD and LED TV's all the time.

There are two plastic polarizer sheets laminated to the outside of the glass, one horiz, one vertical. When the glue starts coming loose, or de-laminating from the glass, it results in a darker smudge, a blob shape, with irregular edges. There is no fix but to replace the panel, so, learn to live with it or replace it.

My guess is uneven glue or glue solvent application on the assembly line.

I have 35+ years as a TV repairman, now with Best Buy.