While from the instructions above, it might seem relatively easy to clean a watch and strap (and it is), there are some critical factors to consider before you launch into the task. So, before you grab your scrubber and soap, here are some things to think about.
As you may have guessed, the far most important consideration is knowing the water-resistance of your watch. Suppose your watch lacks water resistance, such as a vintage dress watch or a more fragile chronograph. In that case, you will need to clean it differently than a modern, professional dive watch or even a moderately water-resistant piece like Rolex datejust such as a field watch. Every expert we spoke to stressed the importance of this factor, as the entrance of even a tiny amount of water and soap into the case can quickly devastate a watch.
Along these lines, before you begin cleaning, we recommend double-checking that the crown of your watch is pushed or screwed in completely; he also recommends not operating the pushers on the side of the case during cleaning if the watch is a timepiece, as having an unsealed issue, via an open crown or moving pushers, reduces the overall security of the watch against water.
The following two considerations to think about are the age of the timepiece and its last servicing date. Both of these factors contribute to the adequate water resistance of a watch, as older pieces and those that have gone a long time without servicing will have diminished water resistance as a result of aging and drying gaskets.
Gaskets will dry out in several years, making them brittle, and if they crack, moisture can get inside and rust your movement. A timepiece has a crystal, case back, crown, [and] tube, and some also have pusher gaskets, and if one of them fails because they are old and dry, moisture can damage your timepiece.