Should I use sandpaper to clean the rust from the tools (e.g. Needle-nose pliers), or can I soak them in vinegar or lemon juice?
Would I be better off just buying new tools (which can be an expensive choice for expensive tools)?
While I don't use hand tools much, I certainly own a lot of hand tools. This happens when you sell them all day. Norm Abram at This Old House provides some pretty good tips on cleaning rust from tools.
His tips, summarized:
But once rust appears...
For seriously rusted tools...
Klein makes an excellent guide that covers nearly all hand tools they sell. Check out the free, downloadable PDF "Proper use and care of Hand Tools" available here.
I've used this stuff; amazing. One of the most amazing products I have ever got my hands on. I had a drill press left in the rain for two years. I soaked the parts in this and restored to near brand new. The original machine marks can still be seen.
Harbor Fright carries gallons for $20. You can reuse it over and over too.
I put some pics up in this old thread: How to clean rust in hard to reach points on a tool?
I've always just used steel wool etc. and elbow grease.
But if you really want to get crafty, pull rust from your tools using electrolysis. Check out ToolNut's step-by-step instructions on how to make a DIY electrolyzer for about $40 at instructables.com.
is what I was told to use - have yet to try it
My mom taught me how to use crumpled up aluminum foil dipped in water to scrub away rust spots on chrome. The beauty of this is that the aluminum is softer than the steel, so less scratches. I won't say no scratch marks, because some of the rust particles or chrome flakes might get ground in. Obviously you need to dry your piece thoroughly after using water on it, especially the nooks-and-crannies.
To clean old rusty tools, old shears, or even old rusty needles, soak them overnight in ketchup. Some may need a second soak. Clean them with hot water and dry them, and apply a thin coat of coconut oil or olive oil. Store in a dry tool box with silica gel; cat litter also works to keep them dry.
Vinegar does wonders for rusty tools. Just be sure not to leave it on for too long as it will weaken the metal. I am sure this is the same with other rust removers.