Re-Installing Mac OS X Mountain Lion for Resale

I have recently sold my iMac on eBay. I have a MacBook Air and was not fully convinced when I purchased it that it would be good enough for a main machine. How wrong was I, which left me not really needing my iMac hence the reason for the sale. Therefore I needed to wipe it and then re-install the OS ready for sale. Here is how I went about this.

Previous to Mac OS X Lion all Macs shipped with Install discs containing the Operating System and any additional software that was installed on the machine. However starting with Lion and afterwards the Mac App store meant that Mac OS X was all done with digital downloads and therefore Apple stopped providing install discs with Macs. What Apple failed to announce in a prominent place was that all Macs then included a Mac OS X Recovery partition which could be used in order to restore your machine to a vanilla install.

With this in mind I took the steps below in order to wipe my Mac and re-install the OS ready to set the item after a sale.

  1. Backup all data from the Mac. I use Time Machine with a Time Capsule and therefore I just checked to make sure that the latest backup had run correctly (which it had) and therefore I knew all my stuff was safe.
  2. Deactivate the computer in iTunes (should you use this for your music etc. of course). Purchases from iTunes are only allowed to be played back on 5 computers and therefore you should remove this one as you will no longer need it again.
  3. Deactivate any other software that you may have installed that is only authorised for one machine. I was running Adobe CS5 and therefore I needed to deactivate this so that I could then activate this on another machine.
  4. Sign out of iCloud services and then turn them all off.
  5. Next you need to restart your Mac, holding down the Command + R keys which will restart your Mac into Mac OS X Recovery Mode. From the screen that appears you should select Disk Utility.
  6. Here select the main disc in your Mac with all your stuff on it (probably called Macintosh HD). On the right panel click on the Erase tab and then select security options below. I would not choose anything lower than to zero out the data but would recommend higher. The higher you choose the longer the erase will take (it could be anything from a couple of hours to 15 hours depending on the security level you choose and the size on your Mac’s hard disc).
  7. Once the disc has erased close Disk Utility and then click on the “Re-Install Mac OS X” option from the window. Follow the instructions here. One thing to note here is that it will ask you for your Apple ID at this point. I was worried that this would ’embed’ my Apple ID into the install – something I did not want as I was selling the Mac. However this is not the case as your Apple ID is only used to verify that the OS is legal.
  8. Once this is done your Mac will restart and then arrive at a screen for your to start setting up your Mac with a language and user etc. At this point press Command + Q in order to quite the installer as you want the person that has bought the machine to go through this.

Hopefully the purchaser will have no problems with setting the machine up from here as it will be as new for them when they turn it on. The one that I did wonder about was what happens if the disc fails? This would mean there is no recovery partition. Perhaps there is the option to build a bootable recovery thumb drive? More research needed!

Published by

Mark Wilkinson

Lead developer & owner at Highrise Digital @highrisedigital. Develops the @wpbroadbean plugins. Former teacher.

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