a) Use an intermediate object to transfer or carry out an action.
b) Connect one object temporarily with another that can be easily removed.
EXAMPLE:
For the non-destructive monitoring of the degree of setting of polymers, a magnetic powder is added to the substance. During setting, the changes in the permeability are measured.
For a loss-free supply of current in molten baths, easily removable metal electrodes with a higher melting point are used.