Help with UltraCal Molding? An error.

[NSStudios]

Hey everybody!! Just recently I finished sculpting a Halloween 4 replica, and I made the molds (some leaky edges but we got that solved with some plaster and clay to plug the gaps lol.

However, I did my first casting from the mold and I had some issues. The latex thickness (dwell cast for an hour) was pretty uniform, but in some areas it was almost paper thin. Like there was something there stopping the plaster from soaking up the latex to build thickness. After examining the mold, it looks like there's still some crystal clear left on the mold in those exact spots. Would that cause the issue I'm having? And if so, does anyone have any clue how to fix it? Thank you all so much!!


Nathan

 

[ChickenHaunt]

Yep, the way the latex is able to build up a thickness during the dwell is that the porosity of the plaster (or stone, in your case) draws out the moisture (ammonia) from the latex. If there's crystal clear on the mold surface, it's going to block the absorption there. I always use a mold release on top of the crystal clear. Remember, crystal clear acts as a sealer, not a release.

At this point, I would scrub at those crystal clear patches with some acetone to try to dissolve them and wipe them away.

 

[NSStudios]

Yep, the way the latex is able to build up a thickness during the dwell is that the porosity of the plaster (or stone, in your case) draws out the moisture (ammonia) from the latex. If there's crystal clear on the mold surface, it's going to block the absorption there. I always use a mold release on top of the crystal clear. Remember, crystal clear acts as a sealer, not a release.

At this point, I would scrub at those crystal clear patches with some acetone to try to dissolve them and wipe them away.

Thank you!