This beautiful thread made by DMC has become very difficult to source. It is an equivalent weight and texture to cotton perle no.8 but wears much better. It can be used in long lengths without becoming tired and fibrous. I love this thread for heavier drawn thread, pulled thread, Hardanger and textured surface whitework. It also takes dye very well and is effective as a soft string padding for silver metal thread embroidery.
You may also be interested in my Fundamental Whitework book, and my Essential Tips for Designing and Working Fine Whitework Embroidery book.