I used CA glue to bond two parts of a model together in preparation for making a mold of it. I used Smooth-On Mold Star 20T (platinum cure) silicone. In places where the CA glue was exposed on the outer surface of the model, the CA glue appears to have inhibited curing of the silicone.

Does cyanoacrylate glue inhibit platinum cure silicone, or specifically Mold Star 20T? Can I avoid this by using tin cure silicone, such as Smooth-On OOMOO 30?

  • 1
    This gets into the material chemistry. Other people might have experienced a similar effect, but your best bet for technical information and workarounds might be to contact the manufacturer.
    – fixer1234
    Commented Dec 7, 2019 at 23:08

1 Answer 1


cyanoacrylate itself will not, however many brands of cyanoacrylate have additives which can.

Sulfur is your problem. P-silicon and sulfur do not mix.

I work primarily with fossils and use completely additive free cyanoacrylate, the downside it has to be used quickly as it has no stabilizers.

We don't use much platinum based silicon just becasue even trace amounts of sulfur in the fossils themselves can prevent it from setting up, but I have used to for artifacts. Likewise trace sulfur in the glue will also prevent it from setting. Any sulfur at all prevents P-silicon from setting up and many brands of cyanoacrylate glue use sulfur based stabilizers. many accelerator sprays also contain sulfur so don't use them if you can help it.

tin based silicon tends to be more chemically forgiving, but has greater shrinkage as it ages (months to years).

So you can switch silicon or find additive free cyanoacrylate.

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