13. Molding and Casting: Tyler, Andrew, Zaina¶
Tasks¶
Group: Review the safety data sheets for each of your molding and casting materials. Then make and compare test casts with each of them. Compare mold-making processes. Tyler Andrew Zaina
Data Sheet¶
Smooth on: Mold Star¶
Mold Star™ 30 is a platinum-cure silicone rubber designed for mold making, featuring an easy 1A:1B mix ratio by volume or 100A:96B by weight. It cures at room temperature with no need for vacuum degassing due to its low viscosity. Mold Star™ 30 is suitable for casting wax, gypsum, resins, and low-melt metal alloys. The rubber has a pot life of about 45 minutes and cures in approximately 6 hours. It cures to a blue, medium-firm rubber (Shore 30A). Users should thoroughly mix both parts before combining and avoid surfaces containing sulfur, which can inhibit curing. Vinyl gloves are recommended, as latex can interfere with the curing process.
Key Properties:¶
- Pot Life: Approximately 45 minutes
- Cure Time: Around 6 hours at room temperature (73°F / 23°C)
- Shore Hardness: 30A
- Color: Blue
- Mixed Viscosity: 12,500 cps
- Heat Resistance: Up to 450°F (232°C)
- Shrinkage: Less than 0.001 in./in
- Mix Ratio: 1:1
XTC-3D¶
XTC-3D™ is a protective coating designed to smooth and finish 3D printed parts. It is a two-part epoxy system that should be mixed and applied with a brush. It self-levels to eliminate visible print lines without leaving brush strokes. It has a pot life of approximately 10 minutes and a cure time of about 4 hours. XTC-3D forms a hard, impact-resistant surface that can be sanded, primed, and painted. It is compatible with many 3D printing materials, including PLA, ABS, PETG, and powder-printed parts, as well as other substrates like foam, wood, plaster, and paper. The coating can be colored using UVO or IGNITE colorants and enhanced with fillers such as metal powders or glow additives. To extend working time and prevent excessive heat buildup, it is recommended to pour the mixed resin into a flat tray to reduce mass. XTC-3D is VOC-free and offers a good solution for getting a smooth, high-gloss finish on 3D printed objects.
Safety Considerations¶
Mold Star™ 30 (Platinum-Cure Silicone)¶
- Use vinyl gloves only.
- Do it in a well-ventilated area to avoid breathing in vapors.
- Avoid touching with sulfur-containing surfaces
- Keep it in sealed containers and away from moisture.
- Clean spills with soap and water
- Uncured silicone is difficult to remove; you might need to use paint thinner from personal experience of scrapping the mess off at 7 in the morning
XTC-3D¶
- Mix in small batches to prevent heat buildup.
- Apply in a ventilated space. Still don’t breathe in the evil fumes.
- Wear safety glasses and vinyl gloves during handling.
- Do not eat or drink while using.
- Wash skin thoroughly if contact occurs. Seek medical attention if it gets worse.
Molds¶
The first mold we made was a 3D printed mold. We designed it in Fusion 360. This allowed us to quickly prototype and make adjustments as needed. While it was fast and convenient, the surface finish had small visible layer lines, so we had to add a layer of XTC-3D to smoothen the surface.
The second mold we made was milled from a block of machinable wax using the CNC machine. This process took more time compared to 3D printing, especially when setting up the tool paths and ensuring the correct milling depth, but it resulted in a much smoother and more precise mold with a high-quality surface finish.
Since the molds we made were hard, we needed the cast to be flexible and soft. We measured out equal parts of A and B and poured them into a mixing container. Then we stirred the mixture thoroughly until it was fully blended and uniform in color, making sure to scrape the sides and bottom to avoid any unmixed material that could affect the curing process.
Once it was mixed, we poured the silicone into both molds, the milled wax mold and the 3D printed mold. The low viscosity made it easy to fill in all the details of each mold. We made sure to pour slowly and evenly to avoid trapping air bubbles and to ensure the silicone reached all areas of the mold.
We then left the molds to cure overnight, allowing the silicone to fully solidify. This ensures the material reached its final hardness and was safe to demold without tearing or warping.
