The real secret to dealing with rust is to remove as much of it as possible before trying to apply a new finish. Depending upon the configuration of the item in question, removing rust can be a tedious process that requires lots of elbow grease. In the end, your goal is to remove the rust down to bare metal.
When stripping a fixture of rust, you need to remove any rusted screws and fasteners — which is sometimes easier said than done because the rust can cause the fasteners and the metal structure to freeze together. Here are some ways you can remove rusted fasteners:
Saturate the fastener with cutting oil: The cutting oil helps dissolve a small amount of the rust and acts as a lubricant to help free up some frozen connections. In combination with a screwdriver, pliers, or a wrench, cutting oil can be a favorable ally.
Don’t count on using penetrating oil to remove rust. Penetrating oil breaks down a certain amount of rust, but it isn’t considered a good rust remover.
Use heat to remove the fastener: A heat gun or propane torch causes a stubborn nut to expand and break loose from the bolt.
If you plan to use heat to remove a fastener, be sure to first wipe off any lubricant or cutting oil you may have applied because the combination can cause a fire.
Use a drill and a hacksaw: When all else fails, this usually does the trick.
Install rust-free replacements after you’ve eliminated the surrounding rust and refinished the object.
The various methods (and tools) you can use to remove rust — sandpaper, flexible sanding sponges, solvents, and so on — fall into two general categories: those that rely on elbow grease and those that rely on chemical reactions:
A little bit (or a lot) of elbow grease: Sandpaper, sanding tape, flexible sanding sponges, steel wool, and nylon scouring pads all work well and can be especially useful when working on tubing or twisted and curved material.
In those situations where there is more rust than elbow grease can handle, a wire brush or wire wheel attached to an electric drill can make simple work of stripping rust. A bit of fine finishing with sandpaper or steel wool helps remove any residue that may remain.
Using chemical removers: Some rust simply can’t be sanded or scraped without damaging the fixture. When dealing with this kind of rust, use a chemical rust remover or dissolver. These products contain ingredients that will chemically break down rust.
Rust-removal products containing gelled phosphoric acid, such as Naval Jelly, work best. You either brush the gel on (with a cheap paintbrush) or spray it on, and leave it there for 15 to 30 minutes for best results. Then simply rinse the chemical off with fresh water and dry it immediately. More than one application may be required, depending upon the severity of the rust.
Be sure to wear rubber gloves and safety goggles, and have plenty of fresh ventilation when you’re working with chemical rust removers.