Part 2: Casting the Unicorn
In part 1 of this how-to guide, we showed you how we created the silicone mold using Hapsil™ 360. In part 2, we will go through the steps and materials needed to cast a water clear part out of Ultraclear™ 480N-40, using Hapco’s X-80 Molding Chamber and X-Vac™ Chamber.
Ultraclear™ 480N-40 is weighed out and poured into plastic containers. The B side is then added to the A side container.
The Ultraclear™ 480N-40 is mixed thoroughly for 2-3 minutes. It is a good idea to periodically scrape the sides and bottom of the container. Pouring into a second container and re-mixing is also recommended.
The mixed resin is placed into the X-Vac™ Chamber and degassed, removing air and moisture from the mixture.
The mold is placed upright in the X-Vac™ Chamber and the Ultraclear™ is slowly poured into the mold, leaving about 1/2” from the top of the mold.
The vacuum is turned on and the mold is watched carefully to avoid any material rising over the edge of the mold. One hand is kept on the valve to avoid any mishaps.
The mold box is placed on the X-80 Molding Chamber shelf and topped off with Ultraclear™.
Close the chamber door and tighten the clamps in a crisscross pattern. Slowly open the valve until the tank reaches the desired pressure. We recommend between 70-80 PSI.
The following day, the chamber is depressurized. Once relieved of pressure, the C clamps are loosened and the mold is removed.
The wooden frame is disassembled and the silicone mold is removed.
The silicone mold is laid flat on the bench and the two halves are carefully pulled apart.
The flash and vents are trimmed off. There will be a slight visible line where the parting line was. This can be buffed and polished after the piece is post cured.
The piece is placed in an oven at 80˚C for 8 hours to speed up the cure time and to strengthen it.
If you have any questions regarding this tutorial, or any of Hapco’s products or equipment, please feel free to call us toll free at: (877) 729-4272