In the old days, apparently both talcum and graphite were used for form coating. Why have they fallen into disuse?
Neither is as practical or convenient to use as present-day form oils, even though they have good release properties. Talcum has a tendency to dry out the surface fibers of a timer form, leading to sticking after several re-uses. Essentially the same advice goes for the use of graphite, but there is an extra disadvantage in that the graphite can discolor the concrete. Obviously it is more convenient to use a modern product which combines release and preservative properties in one application.