Re: Rust Spots on shaftsRust is usually a result of moist conditions and changing of temperature. If you have a big enough rust attack that it comes from the inside you can just throw away the clubs.
With the clubs in an uninsulated garage the temperature will swing during the winter. This creates a moist environment, and water is the main catalyst for the rusting process. Water penetrate the microscopic pits and cracks in the metal. The chemical formula for water is H²O, the O stands for oxygen. So now you've got oxygen penetrating the cracks in your irons, the oxygen atoms will combine with the metallic atoms which will form oxide compound, rust.
Sodium will speed up this process, sodium is something you can find in saltwater, which is why iron rusts faster near the coast or salty environment. So, for those of you who live by the coast, keeping the clubs dry is even more important. All shafts I've seen is made of stainless steel, so you'll rarely get the deep rust attacks, but surface rust can always occur. I live by the sea and have 4-5 sets of golf clubs with variable quality, all stored inside, dry and warm, have never seen any signs of rust.
A wet bag will provide some moist, but unless you dip it in water regularly, it should not be a problem. If you store it inside over night, the moist will dampen and you won't have a problem with rust.