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Week 14 - Molding and Casting

Individual Assignment​

Completed the entire workflow at home: made a silicone block mold (using a 3D-printed PLA horse as the master), then cast a replica with two-part epoxy resin.

Process:​

  • Print PLA horse master → secure it in a disposable cup → apply Vaseline as release agent

  • Mix silicone A/B by weight → pour → cure at room temperature (~24 hours)

  • Cut open the silicone block to remove the master (creating two mold halves), drill vent holes

  • Mix epoxy A/B at the correct ratio → pour → cure for several days → demold

Issues & Solutions:​

  • poxy initially showed streaks due to insufficient mixing → restirred until fully uniform before pouring

  • Cast surface retained PLA layer lines → next time, use a sanded/filled master or resin-printed positive

  • Result: A clear epoxy horse, with visible layer lines and micro-bubbles (to be improved in future iterations).

Group Assignment (Chaihuo Space)​

  • Compared silicone brands (HongDa vs ShinBon) in terms of viscosity and cure speed, and summarized safety practices:

  • Always wear gloves and ensure proper ventilation

  • Accurate AB ratio and thorough mixing are critical (otherwise soft spots or sticky surfaces occur)

  • Run a small test cast before committing to the final mold

Key Takeaways:​

  • Weigh accurately, mix until streak-free, wear proper PPE, and log all data (grams, temperature, time).