THAT'S A BIT FLASH

Flash is the unwanted, excess plastic or metal surrounding a part after it comes out of a mould. 

In both injection moulding and die-casting, the two halves of a mould are clamped together, and plastic or metal is poured or pumped in to the cavities that will form the part. 

If the halves do not meet exactly, some of the material will be pressed out in to the gap. When this hardens it becomes flash, and needs to be cut or sanded off the parts. This is not usually a problem with new moulds, but in the case of older kits, etc, the moulds may become worn over time, allowing some of the material.

Some kits have holes that are deliberately 'flashed over', which you may need to open up, depending on how you want to build the kit. In the case of an aircraft model this might be for a display stand, or a choice of underwing weapons.

Here, the holes do not extend all the way through the part. They will be on the inside of the wing or fuselage, but smooth on the outside. If you want to use the display stand or fit the weapons, you just drill or cut through the thin flashed over plastic.

This is the Kovozavody Prostejov kit of the Aero C-3A light transport from Czechoslovakia. A small amount of flash is visible around some of the parts, especially the fuselage halves, and the tailwheel. There is also flash in one of the window openings.

How do you deal with flash?

Paul Adams from New Zealand