It reminds me of a c filter material there is a trick to removing all of the fabric particles from the cuts in the mat.
Cutting mat has grooves.
To clean the fabric whiskers from my rotary cutting mat i dry scrub it with a greenie which is really designed for scrubbing dishes.
Reset the mat borders for the desired spacing of the v groove from the mat opening.
I have one old mat soaking now.
The mat will be soft and be like new again.
I just gently bend the cutting mat over the edge of the table or over a coffee can.
Cut the artwork opening in the normal fashion with the mat face in.
When you use a rotary blade on a hard plastic cutting mat you leave a small groove in.
A v grove provides an accent line around the outside of a mat opening giving an effect similar to the ruled lines on a french mat.
Remove the mat and place it back in the machine face out.
It might not seem like a big deal at first but over time all these grooves add up and can affect your cutting accuracy or worse snag your fabric.
The other posts about using a sharp blade are true as well a dull blade cuts a wider groove allowing the fabric to be pushed into the mat.
When the moisture is gone the mat dries out and will have cut marks and dull your blade.
Soak the mat in room temp water for about and hour let dry.
The idea of using the back of the mat for cutting batting and fleece is a good idea too.