Why does aluminium with paint or anodized coating pay less than bare aluminium?

It’s a yield problem, not a quality problem

When a smelter remelts aluminium, only the metal itself becomes usable ingot — any coating on the surface either burns off as fumes or turns into dross (the oxide skimmings scraped off the top of the melt) that gets discarded or reprocessed at extra cost. Paint, powder coating, and anodized finishes all add a layer that has zero metal value but still has to be accounted for in the weight you’re being paid for.

Anodizing is a slightly different case — it’s technically a layer of aluminium oxide grown from the metal’s own surface, not a foreign coating, but it still increases oxidation loss during remelt compared to bare, unanodized aluminium.

How much it actually matters

The deduction scales with how much surface area is coated relative to the metal’s thickness. A heavily painted, thin-gauge item loses a much higher percentage of its weight to burn-off than a thick, lightly coated extrusion — which is part of why door and window frame offcuts (often anodized but thick) still price reasonably well, while thin painted panelling can be discounted more heavily.

What you can do about it

For small volumes, stripping paint isn’t usually worth the labour. For larger volumes — a stack of powder-coated frames, for example — it can be worth asking the buyer directly what the coated-vs-bare price gap actually is before you decide whether sanding or stripping a sample section is worth your time.

How ScrapTrade Makes This Easier

On ScrapTrade, sellers note the coating and condition directly in the listing, so any deduction is priced in upfront by competing buyers — not sprung on you after the truck’s already loaded.