on substrate 14 to force it into contact with coating roll 24 depending upon the amount of tension on substrate 14 the thickness of the metal coating can effectively be controlled increased tension is created where the chilling roll is horizontally and vertically closest to coating roll 24 the horizontal and vertical location of chilling roll 26 on substrate 14 is controlled by base 32 and horizontal arm 28 respectively for example to enable a very thin coating to be formed on substrate 14 base 32 is adjusted towards coating roll 24 and horizontal arm 28 is vertically lowered towards coating roll 24 conversely to produce a thicker coating onto substrate 14 base 32 can be adjusted away from coating roll 24 and horizontal arm 28 can be vertically raised away from coating roll 24 once coated and cooled coated substrate 14 is advanced by and wound onto take up roll 34 the apparatus shown in fig1 is particularly designed for coating thin layers of alkali metals particularly lithium onto a metal substrate accordingly apparatus 10 must be maintained in a chemically inert essentially free of water nitrogen and oxygen environment to prevent reaction with lithium example of suitable environments include argon helium and neon with an argon environment being particularly preferred being maintained at ambient pressure and temperature lithium and other reactive metals alkali and alkaline earth metals are all very sensitive to.