Trade cards of this type are a
single piece that employ one or more folding parts to produce a
change in the card's image.
This term is used in science and elsewhere to denote a change and,
by rights, should also be applied to mechanical, heat-sensitive, and
hold-to-light trade cards. Current usage, however, limits the term to
only the above definition.
This type is frequently used in before and after trade cards.
However, metamorphic trade cards that don't show the effect of using
the advertised product, such as risque metamorphics, do not fall into
the before and after cards category.
|