PLASTIC STOPPER

Plastic caps. tops and stoppers perform a variety of precise functions. They are moulded from sophisticated materials using the latest manufacturing technology to snap shut, screw fix or even squirt and seal. This stopper is from a tube of vitamins and has a springy spiral to hold the pills in place and stop them breaking up in transit. 

HISTORY

In 1856 in Birmingham, Alexander Parkes invented Parkesine the first man made plastic. However, it was not until the 1940’s and 50’s that there was an explosion of new types and associated manufacturing techniques.

Before plastics, stoppers and caps were made from wood, cork rubber or glass, materials that could be pushed into place to give a tight fit. They were often sealed with a wire fixing to keep them in place. Plastics offered designers the chance to create complex forms which can be precisely fitted and perform complex functions.

MANUFACTURE

This cap was made by injection moulding where a cavity is machined into a steel mould. This space is filled with hot fluid plastic which cools and sets into the required shape. In this instance the mould has then to split open in a particular way to let this complex object to be taken out.

DRAWING

Whilst the core and the top are relatively standard cylinders the spiral springs present a drawing challenge. Each arm is a unique curve and getting the graduation of light to dark on each of them is difficult. Adding to this the outer convex surfaces of the springs catch the light in particular ways as they sweep around the core. The position of each of these elements in relation to the others is also essential to give the impression of a solid 3D form.

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