Franklin Beech, The Dyeing of Cotton Fabrics: A Practical Handbook for the Dyer and Student
“ Lime or Grey Sour.—After the lime boil, the next operation is that of the lime sour or grey sour as it is often called to distinguish it from a subsequent souring. The souring is done in a machine constructed in the same way as a washing machine; the trough of the machine is filled with hydrochloric acid at 2° Tw., which is kept ready prepared in a stone cistern and run into the machine as required (it is not advisable to use acid stronger than this) . After passing through the sour the goods are piled in a heap on the stillage for a few hours. ”
