2011 iMac - screen stain / clouding

[moustachebandit]

My iMac has given flawless service since it was bought 10 years ago.

A recent restore and update to high sierra and I have started to notice a strange issue with what I can only describe as a clouding / stain that gradually grows after a few hours of use.

Initially I assumed it was screen burn from an application tool bar that sits down the left side of the screen (after some long hours you can also make out a ghost of some of the icons) but even when the app isn't in use and I have deliberately not positioned anything on the left side of the screen it slowly develops a dark stain.

Does anyone have an idea on what could be causing the issue? The similar cases I have found online have been permanent, where mine gets gradually worse - so could be the result of something other that dust ingress.

Regards

[Bikerjon]

Dirty or smudgy screens (particularly noticeable on white or grey backgrounds) are a common problem. Dust and heat over many years causes it. Would need a new LCD panel to fix but obviously not worth it on a 10 year old machine.

[eeLee]

I have a Dell that is like this, I believe it is a layer of clue in the screen that does this. The Dell is a touchscreen which means more layers. As the screen heats up, you could be getting that effect. Could that be the case?

[buggalugs]

Think your imac is of a vintage where the front glass is held on by magnets. If that’s the case it’s pretty straightforward to take the front glass off and check if it needs a clean on the inside surfaces.

Later imacs have glued front glass it’s more of a PITA.

SSD it while you’re in there

[sutoka]

I think the clouding is down to condensation I had the same problem with a 2007 24' iMac. After an hour of use half the screen was clouded up.

I remedied it by putting a fan control app which I had on maximum which didn't do it much good but it was an old workhorse and it had served it's purpose.

[moustachebandit]

Thanks for the responses, I pulled the front screen panel off and cleaned the screen behind. Still seems to occur, so I suspect having done some further research is that its dust trapped between the layers of the screen and it needs opening up and wiping down.

A white background has helped reduce some of the staining and dropping the brightness, and shortening the screen saver interval.

Quite tempted to open up the screen and clean the layers and see whether that cures the issue. Dont want to junk the machine consider how good its been over the years!

[andygo]

I think your luck might be in - the new 2021 iMacs are likely to be unveiled tomorrow.