Warming up food on a blech on Shabbos

On Shabbos we always used a blech. Can food be put on the blech to be warmed, then taken off after it was warmed?

Answer

Liquid food may not be placed on a blech on Shabbos to warm up. Solid food which is already fully cooked may be warmed up on the blech, but should not be placed directly on the blech – place it on an upturned pot or aluminium foil container, which can be placed on the blech.

Under certain conditions, it may be permitted to return food to the blech if it had been on the blech as Shabbos began.