Methylene Chloride!? Geez, I've used that before to disolve glass fibre glass from some tools on another project. That is nasty stuff. It SHOULD eat right into the pcb board. I'm skeptical that pcb would be ok, also the labels on the part would be gone. Its a good deturent for sure. I'm guessing that if someone REALLY wanted it they could have it xrayed. But it needs to be done, these things need to be 100% element proof.
chemelec: I went and recleaned all the flux from my new boards (not potted yet). I'll try that. I'm using a ceramic resonator with caps built in, the timing doesnt seem to be screwy, its the inputs (esp on the adc) that are acting up. We'll see this next time with no epoxy, no pigment, and no flux.
I checked the pigment I was using. Its labeled "carbon black", but its really Calcium Carbonate (burnt bones), I checked it out w/ a dmm and could not get a reading even when I touched the two probes togather with some on each probe. It seems like its OK stuff. Just incase anyone wants to try it or somthing like it, I got mine from the university art store, $5, lots of colors.
I guess I could do urethane foam, but I also have some urethane thats used for gluing windows in panels that I'll try, its already opaque, doesnt exothem, and doesn't harden past a durometer of 40 or so. Its CHEAP too.