water is needed for pin mould because water increase humidity and so pin mould grows more quickly.

Get a mould and plaster. Pour water into the plaster and mix. Pour the plaster into the mould and wait for it to dry. Once it is dry carefully take the plaster out of the mould and paint. Note:To get air bubbles out of the wet plaster, gently hit the mould.

Usually it becomes filled with water. After a while, if the house isn't dried and the water removed, then it gets mould. Then it has to be rebuilt, or the mould removed completely.

injection mould

blow mould

extrusion mould

Comprssing mould

When water is standing, there is risk of mould build up. When the bottom of a dish is slimy, this is usually the beginning signs of mould. The water bowl should be changed each and every day if it has not evaporated.