It is not recommended to mix materials int he bundles. It is okay to pad
the loops of a Flemish twist string with a different material. I generally
use B50 dacron in my skinny D97 strings. The problem with mixing within the
bundles is that you have materials of different diameters and that may
creep at different rates. D97 and Fast Flight do not stretch, but all
materials have a certain amount of creep. You will notice this when you put
on a new string. After several shots, you will need to add some twists to
the string. It did not stretch, but it did creep. Generally once a
no-stretch string settles in it will no longer creep.
Putting different materials together in the bundle will cause one to creep
at a different rate, which means all the stress will be on one material,
not a good idea.
In short, don't mix them.
Answered on 1/11/2013 by Anonymous