I don't use normal WD-40, I use a version of WD-40 that is called "Specialist Water Resistant Silicon Spray"... My understanding is that this WD-40 spray is basically some kind of Silicon lubricant that's dissolved in some short chain petroleum distillates; when you spray it on, the petroleum distillates will evaporate off leaving a nice smooth layer of whatever silicon lubricant was dissolved within.
My method
- Soak the bracelet in WD-40 inside a ziplock bag for around 30 minutes to an hour. I don't see the purpose of going longer... it's not like you need the lubricant to soak through 10 years of rust (e.g. we're not soaking a rusted car suspension bolt over night to try to get it to come undone).
- Then I take the bracelet out of the WD-40 and dap / wipe it off with a shop / paper towel.
- Then I air dry the bracelet for 30 minutes to an hour. A good place to dry the bracelet is over the exhaust fan of your computer. This gives you a nice gentle stream of warm air that does wonders for evaporating off the last of the petroleum distillates. I have a heat gun, but that's a bit intense and I'm lazy and prefer to let something hang / sit rather than having to actively point a heat gun / hair dryer at it.
- At this point the bracelet should feel pretty dry to the touch but it'll still smell like WD-40 (gross) and it'll leave a slightly oily feeling on your fingers after touching it (also gross).
- Then soak the bracelet in a bath of mineral oil (I use a clean yoghurt container so I can re-use the oil for multiple bracelets). I usually leave the bracelet in for another 30 minutes to an hour. I'm not sure if doing this removes all the silicone goodness that I put on in with the WD-40 step, but my working theory is that whatever the silicon lubricant in the WD-40 was, it's probably less soluble in the long chain hydrocarbons of the mineral oil than it was in the short chain volatiles of the WD-40 spray. (I'm not a chemist, and I'm sure if there is one who reads this, I'll be quoted and corrected).
- After the mineral oil bath, I remove the bracelet and dap / wipe it as dry as I can with paper towels. This can never get all the mineral oil off, so after I have it pretty dry I rinse the bracelet under gently flowing warm water from a tap, and then dry again with fresh paper towels.
This method has worked really well for me. My bracelets go from squeaky and clicky to smooth and silent.