Hi, I also was unable to cure PDMS using a tough resin mold. Design was very a simple template using Sylgard 184. Curing for two days @ room temp failed, and for 2 days @60C . BOth failed.
Sylgard notes indicate that inhibitors include: Organotin and other organmetallic compounds, Silicone rubbers containing organotin catalyst. Sulfur, polysulfides, polysulfones and other sulfur containing materials. Also Amines, urethanes, amine containing material and other nitrogen-containing materials. And finally unsaturated hydrocarbon plasticisers.
Suspect it’s the amines. But not really sure as who knows what’s in the resin. Apparently there’s more info on Sylgard bulletin 10-022 "but couldn’t find it!
I tried a simple experiment placing two droplets of PDMS on pre-printed objects made from high temperature resin, tough, clear and a glass control. In one of each kind of droplets I added an “inner droplet” of the relevant uncured liquid form2 resin (without mixing). I then put it in oven for 48 hours at 60C. The droplet on glass on its own cured fine. The droplets of PDMS on glass with high temp and clear resins monomers cured almost up to the edge of the resin inner droplet. The droplet of pdms on glass with a drop of tough resin cured around the outside of the pdms droplet but became very tacky toward the centre in quite a wide zone.
The pre-printed clear resin object I used as a substrate had been around for a while (1 year old) and the PDMS droplets on it cured fine although were a little tacky after 48 [email protected] C. (incidentally making it very transparent!)…
The droplets of PDMS on the tough resin object totally failed to cure - they spread out and merged into each other forming a thin layer of uncured PDMS that pooled at the lowest point.
The droplets of PDMS on the high temp resin also didn’t cure very well. In part this was due to the poor design of pre-printed object. I just used some old prints I had lying around. It had holes in it. Interstingly the PDMS dribbled through the holes to form hanging droplets which then cured, except for where they contacted the mold. Forming a solid blob that could move around on the mold, even when upside down. The uncured PDMS close to the mold formed a sort of adhesive.
Conclusion: clear molds OK if they have been sitting around for a year!. High temp and tough: No!
I’m currently printing my mold out of clear resin, and will follow the protocol given above for soaking in water for 2 hours and curing to see if it worked on freshly printed clear objects. I’ll report back in a few days. Also ordered some PTFE mold release agent, which might help.