Fix Epoxy Resin Mold Leak and Calculating Silicone Volume

I recently made my first mold for a silicone mask. It’s a rather large alien mask, so I am also creating a foam insert with FlexFoam III. I wanted to check the volume so I bolted the mold, and poured water in it, before drilling bleeders, but the water is leaking out the bottom. 

Q: what can I do to temporarily patch the leak? I was thinking of using silicone caulk, or flex seal tape, but I’m open to ideas! 

Note: I tired using Sculptex around the bottom edge but that didn't work with the water. 


  • Options
    How you patch it may depend on where the leak is coming from.  Bleeders are usually patched by packing clay into the holes as they start to bleed.  I've also been people use screws to patch bleeders, but I prefer clay.  Sculptex would be a good option there.  I imagine the water is what made the patching difficult, as wet surfaces may not allow the clay to stick properly.  Normally you want to make sure the clay gets inside the bleeders then smear more clay on the outside to hold it in place.  

    I've not tried the flex seal tape, but that sounds like it would be a good option as well.  If you try that, let me know how it works!

    If your mold seams are leaking, caulk or hot glue may be an option on a rigid mold.  Hot glue can be removed with isopropyl alcohol to break its mechanical bond.

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