Micro Bubbles in Silicone Mold

Discussion in 'Resonators Romper Room' started by Patrickg2k, Jul 15, 2021.

  1. Patrickg2k

    Patrickg2k Toy Prince

    Joined:
    Oct 17, 2014
    Messages:
    485
    Location:
    Long Island
    Name:
    PNLToyWorks
    Instagram:
    PNLToyWorks
    Micro Bubbles in Silicone Mold
    There a pinholes forming where the silicone meets the model during the mold making process. I am assuming little bubbles are forming for some reason. They are very apparent when using a pressure pot. I'm following instructions and best practices so not sure what's going on. I did a slow, high pour, from the lowest point. The original sculpt is made from monster clay, which does not contain sulfur, so that shouldn't be the problem. I am using Smooth-On Mold Max 14NV, which does not require a vacuum to degas (since I don't have one). Then I am casting resin (Smooth-Cast 305) in a pressure pot. I'm going to try doing a gloss clear coat and make another mold to see if that helps. Any thoughts?


    LEFT: Cast in a pressure pot. Hundreds of little spikes! RIGHT: Cast without pressure pot. You can still see some marks but obviously not as bad.


    You can see the pinholes if you zoom in, but only because I am pulling on the mold.


    Original sculpt in monster clay.
     
  2. Patrickg2k

    Patrickg2k Toy Prince

    Joined:
    Oct 17, 2014
    Messages:
    485
    Location:
    Long Island
    Name:
    PNLToyWorks
    Instagram:
    PNLToyWorks
    Micro Bubbles in Silicone Mold
    I've gotten some great feedback from a few folks. I'm going to try and pressurize the silicon as it is curing to minimize air bubbles in the mold. I don't have a degasser so that's my best shot right now. I'll update again soon.
     
  3. Patrickg2k

    Patrickg2k Toy Prince

    Joined:
    Oct 17, 2014
    Messages:
    485
    Location:
    Long Island
    Name:
    PNLToyWorks
    Instagram:
    PNLToyWorks
    Micro Bubbles in Silicone Mold
    Pressurizing the silicon as it cured definitely worked. I basically made the exact same mold again but pressurized the silicon at 50 PSI for the full cure time. The pressurized resin casts that I did with this new mold were pretty much flawless.

    The only downside to pressurizing the silicone molds as they cure is that the original sculpt/model cannot be hollow in any way. It will become deformed or broken. I thought this could be an issue so I tested this theory with a test sculpt made of Monster Clay (basically wax) with an aluminum foil bulked out inside and it collapsed / deformed in the pressure pot. I assume something similar would happen to sculpts made of Sculpey that have an aluminum foil inside, but I can't say for sure. Since it is cured with heat and hardened, it would probably crack/break a lot. I'll test that next.

    I also worked out a very clever method to provide structure to a cylindrical mold. I'll probably make a video and post it at some point on my IG.

    [​IMG]
     
    Urk, bunnyboy, Bob and 1 other person like this.

Share This Page