Aluminium coffee gear

Aluminium conducts heat roughly three times better than stainless steel, which is why it dominates the one category where even heating over a flame is the whole job: the aluminium moka pot. It is also light and cheap. The trade is that it is chemically active in ways steel is not.

The patina is not dirt

A used aluminium moka pot develops a dull grey-brown film inside. That is oxidation plus coffee oil, and traditional practice is to leave it: it seasons the pot and, according to most Italian households and a fair number of roasters, improves the coffee. Scrubbing it back to bright metal every time removes the seasoning and exposes fresh aluminium to the next brew. Rinse with hot water, do not use detergent, and dry it.

Two things it cannot do

It cannot go in a dishwasher: the detergent is strongly alkaline, it strips the patina and leaves the surface dull and chalky, permanently. And it will not work on an induction hob, because induction needs a magnetic base and aluminium is not. Induction compatible moka pots is the list of the ones that get around it with a bonded steel plate.

The health question, answered plainly

Aluminium cookware has been studied repeatedly and food-contact aluminium is regarded as safe by the relevant authorities. What is true is that acidic contact leaches more than neutral contact, and coffee is mildly acidic, which is one reason the seasoned layer is useful: it is a barrier. If it bothers you, stainless steel does the same job with worse heat distribution.

Where else it turns up

Grinder bodies, where it is about weight and cost rather than heat; scales, for the same reason; and hand grinder shells. In none of those is it touching hot acidic liquid, so the care rules above do not apply.

How to tell a good one

Wall thickness and the quality of the casting. A thin aluminium pot heats unevenly despite the material's advantage and scorches the coffee at the base. The gasket and the handle are what fail first on any moka pot, so whether replacements are sold matters more than the metal.