A Serious Case of Flash

Hi Woodsy

You once asked me about flash – the surplus material that you sometimes find around the edges of plastic or metal parts. There may also be flash in areas that should be open, such as location holes or windows.

This happens when the two halves of a steel mould are clamped together, and molten plastic or metal is injected in to the mould under high pressure. If the seal is not perfect, then plastic can ooze out between the halves, leaving a thin web of excess material when the part is removed from the moulding machine.

Here is a really bad example – on a 1/72nd scale Monogram kit of the Grumman F8F Bearcat carrier-based fighter plane. This one was made in New Zealand by an Auckland company called E. Allan Brooker Limited.

At the time this model was produced there were tight import controls on goods coming in to NZ, so a lot of things were produced locally by NZ firms to avoid the need for import licences, and to avoid paying tariffs.

The kit has 'Made, printed and packed in New Zealand by E. Allan Brooker Ltd. Auckland', on one side of the box, and on the instruction sheet. The box also carries two copyright dates: 1967 and 1979.

The flash would need trimming off with a knife, or sanding, before the model could be assembled. Not a difficult job around major components such as fuselage halves, but the smaller the parts, the trickier the job.

Has anyone else dealt with a lot of flash?

Paul Adams from New Zealand