Trouble laser cutting silicone rubber

I've never cut silicone rubber before and I'm having difficulty cutting a thin McMaster-Carr material.

Attachment 467004

The nearest circle is cut from the hole.

I'm using a 30 W Synrad laser with air assist and have tried various settings. The "successful" cut in the photo was done at 7 mm/s and three passes, pausing to pull the swarf out of the way after each cut.

The swarf is swollen and its volume is much more (20 times?) than the volume of the cut. If I don't brush the swarf away the laser can't penetrate through to the bottom of the previous cut.

Has anyone got any tips or suggestions? More air? Less? More shallower cuts?