What the metal
actually does.

Metal is lithographed onto flat sheet and formed afterwards, so the artwork is in the surface rather than on it. Plastic is moulded first and decorated after, usually with a label, a shrink sleeve or a pad print. Carton and film are printed flat and stay flat.

What that changes on a tin is durability more than fidelity. There is no applied layer to lift at an edge, and a matte lithograph stays matte where a matte film scuffs to a shine in transit.

Weight is the first thing a customer registers and the hardest thing to fake. Tinplate at 0.23 mm gives a pack mass and a cold first touch. Mylar and carton have almost none. Moulded polypropylene has some, and flexes under it.

The closure carries it too. A metal mechanism has a defined action and an audible seat. Glass has the mass without the mechanism: a jar closes on a lid made of something else, so the part a customer handles most is not the part they are paying for.

Metal holds its form under compression, which matters in a case, on a pallet and in a delivery bag. A dented tin still closes. A creased mylar bag still closes. A crushed carton does not, and a cracked plastic hinge is a failed pack.

Glass holds form better than any of them right up until it does not, being rigid to the point of breaking rather than deforming. Metal also holds tolerance across temperature, where plastic closures loosen in heat and stiffen in cold.

Steel is separated from mixed waste magnetically, with no consumer decision involved, and it recycles without loss of quality. Glass and carton have collection streams of their own. Multi-layer film generally does not.

What slows any of them down is a second material. A liner holding a seal has to come out before the steel goes in the stream, which is why four lines in our Eco range are specified without one: all tinplate, kerbside with steel, certified to the same standard.

Glass is transparent and metal is not, so a pack that has to show the product needs a window, another material, or a different idea.

Mylar folds flat and weighs almost nothing, so it ships and stores in a fraction of the space. Carton takes a fine print in short runs and folds from a single blank. Both are reasons to specify something else, and both are worth knowing before a format is chosen rather than after.