One of the problems with the mats I've been making is that, if you pick them up to move them, the ropes separate a bit and have to be tidied up when the mat is laid back down. Traditionally this is addressed by sewing the strands together on the bottom side of the mat. I did this on the round mat and it was a tedious process.
Another problem is that the mats tend to slip around a bit just like almost any rug does. This is a bad thing when the mat is used on a sea-tossed deck.
I think I've overcome both of these issues. This is a refinement of an idea I got from another sailor's wife who makes tons of these mats. She smears the back of the mats with marine sealants. The entire bottom of one of her mats is essentially a layer of rubber. As the sealant cures, it bonds the adjacent strands to each other and provides a non-slip surface. The downside to doing it this way is that the marine sealants are quite expensive, it takes a LOT of sealant to cover the back of a 2' x 3' mat, and the bottoms aren't that pretty.
I decided to use common household silicone caulking because it's cheap and easy to find. It still holds tenaciously to anything it touches and provides a nice rubbery surface once cured. I used some "cedar/tan" colored DAP caulking.
I'm hoping that the beads are tall enough to provide the non-skid surface that I want. Won't know until the goo cures which may take a couple of days. As far as whether or not this is an aesthetic improvement over smearing the entire back of the mat, you can decide for yourself.
This mat took 3-1/2 tubes of caulking at a cost of about $3.95 per tube. Compare this to one of the cheaper brands of the marine grade sealant at $18.50 per tube. I estimate that covering the entire bottom of the mat would have taken at least 10 tubes.