So, exploring more-
There are two subtle features here of note in the edge- vertical stripes called “striations”, and, typically near the bottom, the cut may sweep back, that’s “dragging”.
They are not the result of air assist. Nor at they from pulsing of the laser source. At 100%, Tarkin does not pulse (Pearl does, however). It is believed to be from gas venting out as it is cut in a cycle of vaporization making a bubble that pops.
Dragging can be countered by cutting a bit slower overall, without reducing power.
It seems like glassing the edge, and not getting the striations, may be cutting slower AND with lower power to get to the point where the acrylic surface around the cut absorbs enough heat to melt, but not enough to vaporize. By going slower just by itself, this might not melt the edge, as the beam initially slices through and then is mostly hitting the honeycomb.
It’s a surprisingly vaguely understood process, and this may not be entirely correct. Cast vs extruded may give different results, as well as other parameters (color, etc). I went back and forth for awhile.
The most standard test I could do was 10mm x 10mm square, standard surface focus. That’s enough to get the edge doing what it will do. Larger just consumes acrylic and I haven’t found additional value in larger test shapes…