A metallised closure starts with a moulded plastic cap and adds a microscopically thin layer of aluminium under a lacquer, giving a gold, silver or chrome-like surface, often at a lower cost. A metal-shelled closure fits a formed aluminium shell over a plastic inner, which gives a very smooth surface. Here the two are compared on look, feel, shape and finish.
A metal finish on a jar lid or cap can be made in two ways. A metallised closure is a moulded plastic cap with a thin layer of metal deposited on its surface. A metal-shelled closure is a plastic inner fitted with a formed aluminium shell. Both give a pack a metallic closure, and each looks and feels different in the hand and on the shelf.
The cap is moulded first, usually in polypropylene (PP). Its surface is treated so it will accept a coating, then base-coated and loaded into a vacuum chamber. Aluminium is evaporated inside the chamber and settles on the cap as a film measured in nanometres. A clear or tinted lacquer goes over the top to protect the metal, and the tint sets the colour. Silver, gold, rose gold and gunmetal all come from the same process.
Because the metal sits on the surface, the finish follows whatever the mould produces. A polished mould gives a mirror-bright result and a textured one gives a softer, satin look. Ribbed walls, curved shoulders and fine detail all take the finish, and the cap stays as light as an uncoated PP closure.
A shelled closure is built in two main parts. The inner is a PP cap that carries the thread and holds a liner, such as EPE foam, which seals against the neck of the jar. The shell is formed from aluminium and fitted over the inner, so everything the eye and hand meet is metal.
This construction gives a consistent result, whichever colour or profile is chosen: a metal surface, smooth sides and a little more strength and weight - weight can be added to the design if your brand requires the feel of a full metal piece.
Explore smooth, matt or glossy metal shelled pipettes and jar lids in a variety of colour finishes.
Explore metal shelledThe clearest difference is surface. A shell is a formed metal skin, so the outside is very smooth and even, and it carries a little of the coolness of metal on first touch.
A metallised closure keeps the feel of a moulded cap, light and not cold to the touch. On a thinner PP wall, the outline of the internal threads can still show faintly on the outside, and the brand design allows for that, it is the more economical route. Its strength is an even, reflective colour across the whole shape, including ribbed and textured walls, with the colour controlled through the lacquer.
A shelled closure suits a range where a very smooth surface and the look of real metal carry the premium message, such as a cream in a heavy glass jar.
A metallised closure suits a range that wants metallic colour on a more detailed or textured cap, a lighter overall pack, a more economical closure, or a finish that picks up the metallic decoration elsewhere on the product.
We weigh how a closure will be disposed of alongside how it looks. A metallised PP closure remains a single polymer in construction, with a metal layer measured in nanometres. OPRL guidelines suggest that plastics metallised through vacuum or vapour deposition will still be sorted correctly in the recycling stream. A metal-shelled closure combines aluminium and PP, which means it is classed as mixed materials which cannot be separated in standard recycling streams - but it is still often chosen for the smooth finish and the look of real metal it adds to the pack.
If your brand is heading for a metallic look with a simpler build, a metallised closure is worth discussing. If you are considering the two options for a range, our team can put samples side by side and talk through which suits best.
Please note that Richmond Containers CTP Ltd is not an environmental or legal consultant, and you should always secure your own professional advice prior to making business decisions.
