This averages about 40,000 feet per 50 gallons of dye-bath. The baths
may be revived at intervals by the addition of more dye, though this
procedure is uncertain and it is generally advisable to mix fresh
solution.
The addition of a trace of acetic acid (1 part in 1000) will revive
an apparently exhausted bath though as stated above, it is only
advisable to do this in the case of baths containing a single dye.