How to identify scrap metal: 4 quick tests
Yard workers sort metal in seconds with a magnet, a file and their hands. Here's how they do it, in the order they do it.
1. The magnet test
Carry a strong magnet. If it sticks hard, you have steel, iron or 400-series stainless. Those are the lowest-paying metals. Copper, brass, bronze, aluminum, lead, zinc, gold and silver never stick.
A weak pull on something shiny is usually 304 stainless that was bent or cut. Bending can make it slightly magnetic. If something looks like copper or brass but the magnet grabs it, it's plated steel.
2. Scratch or file it
Paint, plating, tarnish and dirt hide the real metal. File a small spot or scrape it with the back of a knife, then look at the fresh color:
- Salmon pink: copper
- Bright lemon yellow: yellow brass
- Reddish gold or brown: red brass or bronze
- Soft silvery white: aluminum
- Hard bright silver: stainless steel
- Dark grey: steel or iron
- Dull blue-grey and very soft: lead
3. Weight for its size
Your hand learns fast. Aluminum weighs about a third as much as steel the same size. Copper and brass feel heavier than steel. Lead feels shockingly heavy for its size, and that's a dead giveaway.
4. Hardness
Press a fingernail into it. Lead marks. Aluminum scratches easily with a key. Stainless barely marks at all, even with a file.
Put them together
One test can fool you; two rarely do. A piece that doesn't stick, shows salmon pink under a file and feels heavy is copper. A light piece that doesn't stick and scratches easily is aluminum.