Woven linen goods are tan in color and often have brown flecks. The yardage must be bleached before it can be dyed successfully. The bleaching fields of Haarlem, Holland whiten most of the European linens of the early 18th century.
Linen woven during the winter months in England was sent to Holland in the spring. The fabrics were soaked in lye, washed and spread out on the grassy fields in the sun for weeks. The process was repeated numerous times and usually finished by October when the fabrics were returned to England ready for dyeing.
The modern chemical industry that developed during the First Industrial Revolution in Great Britain brought us muriatic acid bleaches that eliminated the 6 month long sun bleaching process. Now linen could be bleached in a factory in just a few hours.
When I taught Apparel and Textiles last winter here at Montana State University, I would begin each lecture with a current issue that related to the day's lecture topic. Here is a link to an article about 600 year old linen bras.