The mixture more used for a "HB" is 60% "N" fiber (vaporized) and 40% "S" fiber (without vaporizing). This proportion can be obtained approximately mixing 50% of the boats of "N" fiber and 50% of the "S" fiber boats.

In the case of working with 100% N fiber is very important that the distance between rollers are a little greater than the longest fibers of the cut to avoid a streching in cold which in the spinning would give an unwished residual shrinking.

In order to improve the mixture the ideal is to form a stock of TOPS (breaker boats) the biggest as possible which is stored in several lines and it will be consumed in crossed form (Ejem. Tops 1-6-2-7 etc.). The previously mentioned mixture is the commonest but the proportions can be changed according to the wished final spinning. In the case of the HB the "S" proportion of the mixture would not have to be inferior to 35% since the spinning once dyed will lose burst strenght (N/TEX); exception done of SPECIAL T-56 HB basically for carpets.