When you take your Mac into a Genius Bar, or arrange with Apple Support for it to go off for repair, it is worth spending a little time making sure that it is in a fit state. When it arrives at the repair facility, staff there make a detailed condition report, noting any dust, stains or marks, dirt, and other damage.

In some cases users have been shocked to discover that Apple expects them to cover the cost of repair because their Mac is in such a neglected condition: this should not come as a surprise, as your responsibility under statutory and AppleCare warranties is to keep your Mac clean and well-maintained.

Once you know that your Mac needs to go away, either for repair or to a Genius Bar for possible repair, check that you have the right materials to clean it. Apple provides advice in its documentation, and has a very helpful index to its cleaning advice for different products.

The three most important things when cleaning your Mac are:

• Shut it down and disconnect it from mains power before starting to clean it. Do not reconnect it until you have finished, and it is fully dry and safe to use.
• Do not allow any liquid to enter your Mac at any time. Some advise that cleaning alcohols such as isopropyl alcohol can be used internally, but these contain water and you should never try this (specialists may do so when they know what they are doing, though). If any part does become wet, it must be thoroughly and completely dried before even considering putting power to it again.
• Never use any abrasives, and avoid all solvents (other than small amounts of water, damp not wet) unless they are known to be safe on all the materials which they might come into contact with.

This sounds over-cautious, but I have seen so many Macs and other expensive items ruined because their owners have inadvertently used the wrong thing to try to clean them. Once scarred, they are expensive to restore.

Laptops are particularly difficult in this respect, as they contain batteries (so are difficult to isolate from power completely, making fluids even more dangerous), are often used in relatively dirty environments, and have integral keyboards and trackpads. Leaving their keys and trackpads covered with finger grease when sending them for repair is not acceptable.

Many Macs do have to work in tough conditions. For several years, I supported systems used in sailmaking lofts and other premises which had high dust content, smoke, and more. If you want to obtain warranty service on a Mac in such an environment, you will have to strip it down quite frequently and use dry, clean air to clear out all the accumulated dust and debris. If you don’t, it is at risk of hardware failure, overheating, and even catching fire.

If anyone smokes in the vicinity of your Mac, then smoke and tar deposits will accumulate. One spot to watch in particular is around Thunderbolt ports, where the heat and possibly electrical charge leads to tar deposition. A slightly dampened lint-free cloth with a little mild detergent should be sufficient to remove them.

A lot of this comes down to the obvious. But unfortunately, we do not always see the obvious – like the Mac user who owned a pet bird, which liked to perch on top of their Mac. The repairers had a major task on their hands before they could even open that Mac up to look inside.