bearding can be caused by a number of things- or a combination of a number of things-
fabric quality/thread count is first
a good new (sharp) needle instead of a used dull needle--and the size of the needle being used in comparison to the thread- fabric sandwich.
quality of batting being used
looser weave fabrics are more apt to beard- like flannels/home spuns
if the batting is one that needs close quilting- (every 2"-4") there is more chance of bearding- if the batt has a scrim (like warm & natural) less chance-
if the batting is one good for hand quilting- it can beard more-if the right needle/thread is not used
if the batt is made for machine quilting it may not beard as much= i've had alot more bearding from cotton batts than poly batts- when using poly batts i tend to use Dream Poly-or dream green and have never had any bearding from it
the thread can also play a part- depending on the weight/ply/and fiber content-
it is important to use the correct needle for the thread you are using- use a smooth thread (you can use 'sewers aid' on the thread to help if you determine it is the thread- or if hand stitching bees wax- do not use bees wax if using the thread in a machine.
most of the fabrics you buy at the lqs have about a 160 - 200 thread count- batiks are a tighter weave-
flannels can be 50-150
some of the lesser quality fabrics purchased at big box stores and other outlets will be in the 60-150 range too- those are more apt to beard- but it can be avoided with the right batting, thread, needle combination- they will however after a few washes start pilling like sweaters that are washed in a washer- the better quality fabrics will last through more washings- and poly blend fabrics seldom pill- they are a nice-tight weave- more durable fabric.