What is the source of a dark marbling effect on the cured PDMS surface?

Hello! I produce PDMS flowcells from a silicon wafer-mold. We have a centrifuge from "3T Analysis" and a "SpeedMixer" to mix the PDMS properly (RT 607 A/B by Wacker). If I pour the PDMS directly...

22 January 2015 3,807 11 View