Once upon a time in the 15th and 16th centuries people fought for alum and pirates seized ships to search for this precious chemical. There was a time when the Papacy had the monopoly of alum. Alum was very precious because, as a mordant, it allowed dyed cloth to keep its bright colour. Having brightly-dyed clothes was so desirable.... rather than the muddy or faded cloths which had been tinted without alum. Then Elizabeth I decided enough was enough and the hunt for alum in the British Isles began. They sought it here and they sought it there (Ireland and the Isle of Wight) until it was discovered in great quantities outcropping along the north east coast of England.
These first two vintage publications tell the fascinating story of alum - and it is fascinating. In fact the history of alum is written plainly still upon the north east coast - millions of tons of rock were hacked off the coast and processed and the shoreline. The last publication focuses on earlier dyeing techniques and is also a very interesting read for those interested in this subject.