Ctc are you now are have you ever been a needleworker? If so you should know a stitching technique that framers use all the time"COUCHING".
Couching was originally intened (I think) to do just what you are describeing . You lay a heavier fiber on the surface and then make small close loops around the fiber to secure it in place.We here have used this to lay a fiber called "Japan Gold" .If you use thin enough material(thread) to secure the laying fiber and if you run your stitching needle ,virtualy under the fiber being couched and do so snuggly it is all but invisible.
Therefore I suggest you find some of the stuff needleworkers call "Invisible thread"(actually a very very fine monofilament fiber)and COUCH your Monofilament in place ,by pierceing very tiny holes where the Mono wil lie and run your loops from onr hole to the next and secureing it at the ends under the mat.It is the best method I can think of but it is labor intensive and very exacting work,but if done properly nothing is safer or better.,and with the exception of the holes you pierce in the mat TOTALY REVERSABLE.
BUDDY
Of Needles and Knots
[ 01-18-2004, 12:14 AM: Message edited by: BUDDY ]