A porous separator allows more energy to be drawn from the battery than a nonporous one.
When a wooden case is used, jars made of rubber, or some other nonporous, acid-resisting material are necessary.
When the skin is ready to apply, coat this plaster cast with some nonporous modelling material.
porous po·rous (pôr'əs)
Full of or having pores.
Admitting the passage of gas or liquid through pores.