How do I tell the difference between cast and wrought aluminium before selling a mixed load?

The tests that actually work

Since both cast and wrought aluminium are non-magnetic, the standard “grab a magnet” test used for steel doesn’t apply here. What does help:

• Surface texture — extruded and rolled aluminium (window frames, sheet, brackets, cans) has a smooth, consistent finish because it was formed under pressure through a die or between rollers. Cast aluminium was poured into a mould, so it often shows a slightly grainy or pitted surface, and sometimes a visible seam line where the mould halves met.
• The snap test — bend a thin edge or a small offcut. Wrought aluminium tends to bend or deform. Cast aluminium is more brittle and is more likely to crack or snap cleanly.
• Shape and origin — if it came from something poured into a specific form (engine block, gearbox housing, decorative “pot metal” fitting), it’s almost certainly cast. If it was cut, rolled, or extruded into a profile (frames, tube, sheet, cans), it’s wrought.

Why it’s worth sorting

Buyers pay more for wrought aluminium because it’s a more predictable, lower-silicon alloy that can go back into higher-value products. If you drop off a mixed load without separating, expect it to be priced at the cast rate — the buyer has no easy way to verify the split once it’s all in one pile, and the burden of proof sits with whoever wants the higher price.

If you’re not sure

When in doubt, ask the buyer to grade it in front of you rather than out of sight. A legitimate buyer won’t mind showing you which pieces they’re calling cast and why.

How ScrapTrade Makes This Easier

If you’re not confident sorting cast from wrought yourself, ScrapTrade’s verified buyers can assess a photo listing before pickup, so you get a read on the split — and a real price against it — before committing to one buyer.