I've made double and triple Flemish strings with linen. It looks fantastic, and you can buy it dyed a range of colors, as well a natural and white. Just test the breaking stength so you know how many threads to use, and go at it. I use string makers wax from 3 Rivers, and have made them with and without serving.
Oh, sorry, I meant B-50, not D. Duh.
Dane