Dictionarium polygraphicum. BLUE of the dyers

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol I.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
1735
BLUE of the dyers is one of their simple or mother colours, which is us'd in the composition of others. It is made of woad, indigo, and a pastel brought from Normandy, and of the three the pastel is esteem'd the best and most necessary; woad, though of less force and effect, yet makes a tolerable colour, indigo only makes a spurious colour; yet it may be us'd along with pastel if it be well prepared, and be not mixt in too great a proportion.
Woad, having but little substance, can neither be us'd alone,: is it capable of correcting the indigo without the assistance of pastel.
Some dyers heighten their blue by adding brazile and other woods.
The way of brightning blues is by passing the stuff, when dyed and well wash'd through lukewarm water, or which is much better, by working and fulling the dyed stuff with melted soap, and then scouring it well.

BLUEs are immediately dyed from the whites, without any other preparation than fulling.