Step 9: Molding the Helmet (2 of 2)
For my mold, I chose to make separations using 1/4" MDF to split the mold jacket into three parts. With a complex shape like a helmet, a one-piece or even two-piece mold jacket would be difficult to remove. Drill aligned holes in the MDF partitions, then join them together with wingnuts before applying the mold jacket. (pic 2)
Use Smooth-on's Plasti-Paste to make the mold jacket, applying it evenly in each section before moving on. You'll want to make sure all of the mold silicone is covered by the mold jacket to avoid any registration issues.
Plasti-Paste can dry very jagged. In order to make the mold jacket easier to handle later on, use rubbing alcohol and a rag to smooth out the surface as the material cures. Make sure to only do this on the top coat, as pressing in on the mold jacket while its curing may cause some registration issues with your mold later on.
After the jacket cures, remove the master from the mold materials and re-assemble everything into one empty hollow helmet mold. (pic 3)
- Smooth-On Plasti-Paste
- Machine screws and wingnuts
- 1/4" MDF
- Drill & drill bits appropriate to the size screws used on the MDF
- Mixing cups
- Disposable trowels
- Isopropyl alcohol
- Rubber gloves & smock
- Respirator & safety goggles for cutting MDF