I wrote a post a while back about the problem I was getting with pixelated (fuzzy) icons under Snow Leopard. As soon as you start to use more than a few, the icons become fuzzy – almost like they’re enlarged versions of low-res icons. Sometimes a reboot will temporarily fix the problem, and sometimes using a utility to clear caches can also help, but it’s usually short-lived. If the Apple Support pages are anything to go by, it’s a common problem affecting quite a few people and there’s no fix in sight from Apple.
After a little research (thanks to ‘steepleton’ in the Apple Discussion Forums), I might have found a fix. It’s early days but I tried this about 5 hours ago and all my custom icons are still fine whereas normally they would have been fuzzy within 5-10 minutes of a reboot. Now before I go any further – a warning. The fix involves deleting a hidden system file that Apple probably didn’t envisage people messing with. On the plus side, OS X will recreate this file from scratch after you delete it, but it’s worth noting that while I haven’t experienced any undesirable side-effects on my Mac, your mileage may vary. So… don’t say I didn’t warn you ;-)
The fix involves removing a file called thumbnails.data which is located inside a folder called com.apple.QuickLook.thumbnailcache on your Mac. Now, the path to this file seems to vary slightly because on my Mac Pro I found it in the following location:
On my Mac Mini the path was almost the same except the +h… part (shown in red) had a different name. The best way to locate the file is to use something like Find Any File. It’s an excellent utility by Thomas Tempelmann that let’s you search for files, including ones that Spotlight doesn’t index (which will be the case with thumbnails.data. Although there’s a free version, I highly recommend you get it from the new Mac App Store as it’s a great way to track down things on your Mac that Spotlight doesn’t help you with.
Anyway, back to the matter in hand… Once you’ve located the file you’ll need to navigate to it with your preferred file manager. If you’re using Finder then you’ll need to go to the View menu and turn on the setting that says ‘Show System Files’. If (like me) you use Path Finder then you go to the View menu and select ‘Show Invisible Files’. Having done that, navigate to the thumbnails.data file and copy it to a temporary folder somewhere – a temporary folder inside your Documents folder is probably a good place. Having done that, delete the original file and then empty your Trash. Next, reboot your Mac and everything should look just how it should be – custom icons and all.
I noticed that in my case, the thumbnails.data file was almost 370Mb in size before I deleted it. The new thumbnails.data file that OS X has created for me is under 35Mb and that’s after 5 hours since a reboot and with me exploring every folder I can think of to check on my custom icons. Obviously once you’re happy that everything is working ok, you can delete the copy of the old thumbnails.data file that you made.
I’m hoping that the fix continues to work, and if it does work even for a few days or weeks then I’ll be happy. I hope it works for you too, but as I mentioned above, do proceed with caution because this is an OS X system file that your fiddling with. To be doubly sure, I’d make a full backup of your Mac before trying this. Oh and one last point – when you’ve finished, it’s a good idea to turn off the ‘Show System Files’ option in Finder (or Path Finder) so that system files are once again hidden.