How do I identify whether a metal part is actually die-cast zinc before selling it?
Short answer: Die-cast zinc parts are typically dull grey, relatively heavy for their size, non-magnetic, and often show visible casting seams or slight surface porosity from the moulding process — a simple scratch test revealing a bright, silvery-grey colour underneath, combined with the part not being magnetic, is a reasonably reliable indicator.
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List Free →Visual and physical cues
Die-cast zinc parts often have a dull grey appearance, sometimes with visible casting seams where the mould halves met, and a texture that can look slightly porous or grainy compared to a machined or extruded metal part.
The weight test
Zinc is denser than aluminium, so a die-cast zinc part feels noticeably heavier than an aluminium part of similar size — this comparative weight is a useful, quick indicator if you’re trying to sort a mixed pile.
The magnet and scratch test
Zinc is non-magnetic, ruling out steel. A light scratch on an inconspicuous area revealing a bright silvery-grey colour underneath the dull surface oxidation is a further sign consistent with zinc rather than aluminium (which tends to look different when scratched) or another metal.
How ScrapTrade Makes This Easier
If you’re unsure whether a batch of parts is genuinely die-cast zinc, ScrapTrade’s verified buyers can assess photos before pickup, giving you an honest read before committing to one buyer.
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