Ultracal 30 mold disaster

[cunningham]

I just finished off my mold of a complete bust for a new mask, and the front portion of the face broke in three pieces. Three separate pieces that its, not simple faults or cracks, so needless to say I was almost in tears.
The face itself was unaffected, the crack lying just under the chin area so I am hoping it can be salvaged. At this point I will be satisfied if I can get one pull from it.
I am wondering if anyone else has had this happen and what they did and if it worked. I have tried to glue it with Gorilla glue, the stuff that is water activated. Does this sound like it was a good decision? If it holds, I will put another layer of cement on top, I suppose. Does cured Ultracal stick to fresh stuff? Any suggestions would be really appreciated.

 

[Mr Mold Maker]

Did you put reinforcement in the stone, such as hemp or burlap? If not, next time I'd put it in your second to last layer so if the stone cracks it will all stay together.

I've had luck sealing small cracks with Gorilla Glue's Gel Superglue, but I've never tried a water activated version.

Fresh stone should stick to the old stuff, but it turns out pretty brittle. The old stone sucks the moisture out before the new stuff has time to really calcify and harden.

 

[cunningham]

Thanks for the help Slipnot. Yes, I did use a reinforcement, but instead of burlap I used a fiberglass material, which the sales guy told me worked just as well or better and cut down the weight. The stuff didn't even come close to reinforcing the cement like burlap would have. I am fairly sure this is why I had to break, although I am not sure if I demolded too quickly, only letting it cure over night, the cement still had moisture in it. Thanks again.

 

[ChickenHaunt]

I don't see how fiberglass makes sense. Burlap is a natural cloth, so the stone is able to penetrate the fibers to form a mechanical bond. Fiberglass doesn't have nearly the same texture to bite into, and if the plaster isn't biting into it, it's basically weakening the mold. Plus it's more expensive.

I've saved a mold by using gorilla glue. Just make sure it's clamped tight so the expansion of the glue doesn't affect the fit of the mold. If you do put more ultracal on top, wet the existing stone, so it doesn't leech all the water out of the new mix, and use some burlap as reinforcement.

 

[Junklady]

I've had this happen to me before...more than once. Last time I cracked the nose and part of the chin. I just used more Ultracal to fix it. I wasn't like "glue", but more like chalking and then I sanded down the excess. It's not pretty or perfect, but it worked. I've already ran both my negative mold and silicone appliance and it came out fine.

On the mother mold I don't think I used enough Ultracal. It's suppose to be a 38 parts water to 100 parts Ultracal, then reinforcement.

I totally get your frustration. Last time, I had to walk away from my project for a couple of weeks because I knew I was going to start all over again. Good luck!