Greyish Smudge marks behind the glass screen.

Give it a little time. It grows.

My 2009 iMac 27" has these marks. Became a lot more noticible since I started using X-Plane 10 and had sky showing. Even on a clear day I am flying in grey clouds on my iMac !!!! The screen on my 2007 iMac 24 is great and no marks whatsover. Both are operating in the same place so it is not an environmental issue. This has to be a design issue and as such surely Apple should be adressing the problem of ALL affected machines, whether in or out of warranty.

X-Plane is a demanding application and I am in the market for a more powerfull machine. A top of the range 2011 iMac 27" would have been a good option, but with this problem still being around there is no chance I will be purchasing a current iMac. I'll wait to see if there is a major update of the iMac range later in the year. Unfortunately the secondhand value of my present 2009 iMac 27" has been hugely affected by this problem. I could probably get more for my 2007 iMac 24" !!!!!!!

The Glass panel is not sitting securely against the magnets. This occurs over time. The inside of glass needs cleaning.

You need a couple of "Suckers" to pop the glass off the magnet. Dont use anything to pry it off as it will break. One the glass is off use Isopropyl Alcohol on a lint free cloth to clean the inside of the glass. Dont buff it off as this will cause static and dust will attract. Carefully wipe the LCD Panel with same but do not flood. again leave to dry not buff.

Try to keep the iMac pointing downwards so that dust doesnt land on panel and pop the glass back on. it may take a few goes to clear all dust specks.

I'm sure any Apple repair centres won't charge much for doing this

Thank you for your concern, and tips .. Tafftech. But I'm sorry because this has been said a couple of times here. This problem is NOT simply a dust deposites stuck or accumulated behind the protective glass. You cannot clean it by simply "unclog" the front glass panel and wipe it away.

This smudged, dusty and stained screen on iMac is COMMON and happens INSIDE the lcd matrix due to heat expose, or maybe dust. Thus it is irrepairable, irreversible and obviously .. uncleanable .. It's not that simple otherwise this thread would not 40 pages long. You should read some of the post. But once again, thank you for your concern, and tips .. too bad it's not much of a help.

And one more thing. Last week or so, I've read a few comments or rumors here about "NEW KIND OF SHIELDED LCD" that will be used to replace your screen from now on, which states that Apple would use new shielded LCD so the smudged display will less likely come back. Well I'm sorry to burst your bubble, I have no evidence whatsoever, but I dare to say that rumor was simply a lie.

I have been told once by Apple Technician when I got my iMac display replaced for this very same problem about 4 5 months ago, he told me that Apple use the new kind of LCD which more resistant to heat and dust so the problem wouldn't come back. But NO, that was a lie, plain and simple. My LCD has been showing the same symptom for the last 2 months. And I will be BACK this week to replace my iMac display for the SECOND TIME.

So yes, please .. don't believe what they say, it's simply a BOGUS just to calm you down. There is no real solution available unless Apple move the heatsink away from the screen, which means? Apple have to redesign iMac completely, and our poor iMac will indefinitely carry this problem.

Aftre mz bad eperience with AppleCare in mz previous post Apple replaced mz screen for the fourth time. This was less than 1 month ago. Last week the grez spots returned. So less than one month after replacing the screen!

I called AppleCare last week, just to mention this. I didn't expect anything from Apple after mz last contact. Guess what? I got a brand new iMac 27 I5 3.1 gHZ!!! I am glad that Apple regained my confidence, but I'm also painfully aware that most of you stillhave to dela with the screen problem. I really have no idea whz they changed their policy in my case, the only thing I did last time was sending an email with a picture of my iMac in my livingroom to show them that the Mac was not located in a coalmine....

They made clear that this was a very exceptional step and that I was given this privilige because of my real bad misfortune with that Mac.

I hope al of you will have your problems resolved as well in short time.

Good luck!

@Churcill .. Wow congratulation for your unit replacement!

I think it's more like a gamble, sometimes Apple would kindly replace the whole unit after 3 4 times of same replacements, but on other times, Apple would just simply replace your screen again and again and again until the warranty/AppleCare expired, or on some rarer bad times, Apple would refuse to replace the screen after X times just because they think it's an environmental problem and user's fault. It really depends on store manager behalf, I think.

But yeah, you're fully aware that it is a part of good news and bad news. Good news is that you get a faster iMac, for free yeah? 😀 ... Bad news is, many 2011 iMac is not escaped yet from this serial horror (mine, which is 3.4GHz i7 included). In my experience, the smudged display would appear on upper right corner of the screen, so you might wanna start lurking there.

And also you can try to slow down your iMac workflow, make it runs cooler, ramp up the fan with smcfancontrol until GPU heatsink stabilized on 40 - 50C, and don't make the GPU works hard too long, which in result would make GPU heatsink heated, and accelerate the smudging process.

I experienced that with non-gaming and GPU intensive task, smudge appearance and growth appear to be slowed down over the same period. And this empower my hypothesis that this whole thing started with one word. HEAT 😠

I don't know what makes the iMac any different, even iPad is essentially a portable iMac, the guts and innards located right behind the screen, and sometimes your iPad gets warm, but no report of iPad have this smudged display issues like iMac have.

Hey, all:

Just wanted to drop by and update my experiences with the iMac screen smudging. Quick recap: iMac 27" bought in Oct 2010 developed the smudges by Oct 2011. Apple was good enough to replace the screen even though it was out of warranty.

We're approaching the five month mark and so far, so good. I've made a few adjustments when using my iMac since then:

1. I've eased up on playing games. I was playing Left 4 Dead and Team Fortress 2. Not sure how much stress they put on the GPU, but the graphics in both games probably heat up the computer.
2. I've been turning off the computer at night, rather than letting it go to sleep.
3. Prior to Smudgegate, I got lazy and had a DVD sitting in the disc drive. I've since made sure discs are ejected when they aren't in use.

I have no idea whether these adjustments make any differnece or not. My gut feeling is that they don't, but who knows? I'd like to avoid any more screen replacements. I probably should look into smcfancontrol.

Good luck to everyone and talk to you later.

Hey. Add one more to the fray. The Genius Bar people denied my request for a replacement under warranty as "damage caused by the environment". It seam that the fact dust can penetrate the innards of the LCD panel itself is not so much an assembly or design fault than the fact there is dust in the air at all.

It appears Apple is trying to avoid it's legal obligations. I'm currently looking at my options.

Hmm... That's strange. If I were you, I would make another appointment with the Genius Bar. Last week I brought my iMac 27" mid 2011 model to the Apple Store in Amsterdam. The Genius analyzed the problem and said to me that the smudges are a common problem. He said that he is going to replace the screen for free. The next day I could pick up my Mac and now I have shiny new LCD panel.

Sure thing. Im going back, first thing. I've studied the warranty some more along consumer protection act. They have no leg to stand on. The smudges are not caused by the environment. They are the results of the defect.

I'll keep you updated if you care for it.

For the first time last night, I noticed what seemed to be a "smudge mark" in the upper right hand cormer over the day and time of my imac. In fact I tried to clean it, but it clearly seemed to be "under the glass." I was in Safari, so I just happened to close Safari. At that point the smudge disappeared and the day and time was clear as it usually is. I re-opened Safari, and the screen froze. All that wouold move was the cursor. Only way to deal with the issue was to do a hard shutdown.

All this happened soon after the mac came out of sleep

Hey. I joined this thread about a month ago. I have three iMacs in differenet locations. In the course of a month I visited all places, looked again and found same problems everywhere. After my fantasies online about revenge against Apple I was censored, but now I feel pretty sure that 100K+ users having the same problem deserve the right to be heard. My personal loss is about 3,000 USD because nobody is going to buy my used iMacs with this stains on their front. Next few days I'll figure out lawyers and place, like Facebook or Twitter where I would offer to consumers hurt by this problem to unite. We will force our beloved Apple to pay for its mistakes.

Got to amdit I agree with Antonio999. I complained about by 2009 with the same problem and was told it was an environmental issue. I said so how come my 2007 24" sitting right beside it and 2.5 years older has no problem whatsover.

I have got right into X-Plane 10 recently and that really needs a high spec machine. I have grey coulds on it all the time I fly it now. I am looking to upgrade it later this year when I expect an updated range of iMacs to come out. I was in a local Apple store a few days ago and the salespeople I spoke to denied complete knowledge of any screen issues with the present range. I said I was very disspaointed as the secondhand value of my Mac has plumeted due to this issue, in fact my iMac 24" is probably worth more.

I have been a Mac user since the mid nineties and have bought loads of Apple products (probably getting on for a record purchase history) and this is the only product I have had problems with, but is is also by far my biggest investement. I keep buying Apple products because they are quality items which work great and are a joy to use. Because I pay so much for them I do expect them to last and if there is a design issue then I do expect that to be addressed by the manafuafcturer.

They did excellent recently when my 2005 iPod Nano was part of a universal recall and I ended up receving a latest version Nano replacement. My old Nano was still working fine but love the new nano.

Apple has made substantional money out of me and I am overall very happy with their products. I am very serious about going for a top end updated range iMac when they come out later this year, but do expect them to demonstrate customer support by coming up with a solution for this grey smudge mark before I go ahead with what I have always seen in the past as a sound INVESTMENT (Not if it looses value far quicker because of a manfuacturing fault)

Come on APPLE, you have enough money to sort this problem, do the right thing, please.

However I will keep up to date with Antonio999's campaign, and will give my support if Apple dosn't respond soon.

Ditto, here. I will sign on, and I will yell along with the rest of you. What really bothers me is that neither time the glass was replaced, did the tech who came here acknowledge the problem, or even allude to thefact that itis widespread. Each time, the guy seemed puzzled and said he did not know what could have happened. Since I did not do any research online, figuring this was not the kind of problem which was occurring regularly, I never acted on it with Apple. My warranty on my 24 edxpired at the end of January.

I have also been an Apple user since about 1980, and have stocked the house in recent years with three iMacs, iPad, iPod, iTouch, etc. I think my loyalty should have some rewards,

For starters, I have emailed the folowing to Apple. I will follow up with a call next week. "I have only now become aware of the extensive problem involving gray "finger like" gray smudges behind the glass of tons of iMacs produced within the past few years. My glass was replaced twice in the last year or so, and never did Apple, or the tech who came here, acknowledge the problem. The two techs simply expressed surprise. After reading about all the problems, and the fact that Apple has known about this for some time, I find myself extremely annoyed that Apple did not acknowledge the flaw in these machines, and offer to replace them. My warranty expired two months ago, and I now have the same smudges back again, after only two months since the last exchange of glass panel. I have been a loyal Apple customer since 1980, and purchase Apple products regularly, and feel that my loyalty has been misplaced, since Apple does not seem to have any loyalty to me, as a customer. I want someone from Apple to contact me, and let me know what you are planning on doing about replacing these faulty computers, which interfere with most programs,and especially with photo editing, and other programs which rely on screen integrity. My two newer iMacs do not suffer from the same problem, and there is no reason my 24 has to suffer, either."