Instead of discarding old or somewhat rusted nuts and bolts, repurpose or recycle them. In some cases, those stray hardware odds and ends might be just what you need for another project, or they could come in handy for a DIY art piece. As a last resort, the items could be sold as metal scrap or given to someone in the neighborhood that collects items for the local metal scrapyard.
Look Through Them First
If you're pulling old hardware off an item you're tearing out or tearing down, there's a good chance at least some of the hardware still has a useful life. For instance, vintage door hinges and other hardware may be sought after by those wishing to keep their older homes looking as original as possible. Take a good look at all of the hardware you've reclaimed and sort it into separate piles based on purpose, and also based on condition. Even old screws are reusable as long as they're not stripped or bent.
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Place the items that still have some useful life into one pile, and items that are rusted or damaged in another. There's still a chance the old rusty or otherwise damaged pieces can be reused; it just may take a little more effort to find their ideal purpose.
Ask Neighbors and Friends
If the hardware is in decent shape, there's a good chance someone nearby wants it, even if the pieces are just basic screws, nuts, washers, and bolts. Local social media groups are a good place to post your castoffs if none of your immediate neighbors, friends, or family members want them. Look for groups specific to your own street and neighborhood. Localized Buy Nothing groups are an excellent resource for both acquiring and giving away items no longer needed, and there's a good chance someone in your group wants that hardware.
Donate Useful Hardware
Organizations such as the Habitat for Humanity accept useful used hardware, depending on what you have on hand. The organization's ReStore shops are almost like home improvement stores with all the items they accept and sell. It's best to contact your local ReStore before visiting to ensure that it will accept the type of hardware you have to offer. If so, it's a good idea to separate items that don't belong together so they won't have to.
Reuse and Repurpose
If you know how to weld, scrap hardware comes in handy for making all sorts of metal art pieces, from small nuts-and-bolts figures up to large outdoor sculptural art. Other local metal artists may also want the materials if you won't use them.
For basic materials, such as nuts or bolts, there's a good chance you'll find a use for those somewhere else around the house. The snowblower or lawnmower might need a lock washer you've salvaged from another piece. Your front door might need a replacement hinge screw. Keep your sorted used hardware in clear metal jars or labeled bins so it's easier to find what you need when you need it.
Contact a Metal Scrapyard
For old hardware that's in bad shape, such as bent, rusted nails, contact local scrap yards to see if they accept that particular item. Some may specialize in particular metals, so it's best to call before visiting. Since scrap metal has a relatively low value, it's more worthwhile if you have a lot of it. If you don't have much, ask your community groups if there's anyone nearby that collects metal to scrap, as there often is.