Steel, aluminium and copper can be told apart in the field with a magnet, by weight and by colour, and each is worth recovering for a different job: steel for structure and tools, aluminium for light sheet, and copper for wire and pipe. Make sure wiring is dead before touching it, and wear eye and hand protection, because cut edges and flying sparks injure people faster than anything else in metal work.
Part of Building Material Recovery
A building holds metal in framing, fasteners, roofing, ducts, pipes and wiring, in forms that are easy to confuse. Sorting first saves effort in cutting, working and trading later.
Sort By Metal Before You Cut Anything
Metals differ in how they cut, how they work and what they are worth. Magnetic steel is structural and forgeable. Aluminium is light and soft. Copper conducts electricity and heat, resists corrosion and is easy to work, making it the most valuable recoverable metal in most buildings (parent article). Brass, zinc and lead turn up in fittings, coatings and old pipes.
Where they hide:
- Steel: framing members, nails and screws, rebar, roofing panels, ducts, appliance cases.
- Aluminium: siding, gutters, window frames, ladders, cookware.
- Copper: electrical cable, water pipes, plumbing fittings, heat exchangers.
- Brass: valves, fittings, locks and hinges.
- Lead: old pipes, flashing, solder and weights; heavy and soft, and toxic to handle carelessly.
What You Need
- A magnet, a file and a scale or a feel for weight.
- Hacksaw, snips, cold chisel, bolt cutters; see Cutting & Shaping Metal.
- Eye protection, leather gloves and boots.
- Sorting bins, one per metal.
Method: Identify, Cut, Sort
Step 1: Identify the metal. Use the magnet and the weight, colour and spark tests on Metal Type Identification.
Step 2: Make it safe. Wiring may still be live if any local power source exists. Treat it as live and de-energise the source, or confirm it is dead with a tester, before touching; see Copper Wiring & Plumbing.
Step 3: Cut to carry. Reduce long pieces to lengths you can handle, using the right tool for the metal.
Step 4: Strip and clean. Remove insulation and fasteners. Clean copper is worth more than insulated wire.
Step 5: Sort and store dry. Keep each metal in its own bin, and store off the ground to limit rust.
Common Mistakes
- Mixing metals in one pile. Re-sorting costs more than sorting.
- Cutting galvanised steel with heat in a closed space. The zinc coating gives off harmful fume.
- Assuming that anything silver-grey is steel. Aluminium and zinc look similar.
- Cutting before checking for live wire or gas. See below.
Safety
Live wires, cut edges and sparks
Treat all wiring as live until proven dead. A cut sheet or a sheared edge is razor sharp. Grinding and cutting throw sparks that ignite fuel vapour and dust, so never cut or grind where gas, fuel or solvent vapour might be present, and never use a flame to test for a leak. Heating or cutting galvanised steel produces zinc fume, so work in the open air. Wear eye protection and leather gloves for every cut.
What’s Next
- Learn next: Metal Type Identification — telling the metals apart
- Combine with: Cutting & Shaping Metal — getting each metal out of the building