Group Assignment 16: Moulding and Casting¶
The objective of the group assignment this week is to review the safety data sheets for each of the materials we will be using to mould and cast our objects.
Ferris File-A-Wax Blue¶
The MSDS for this material is available online here
The solid wax is not considered dangerous except when breathed as a dust or as fumes. As a molten substance it is more obviously a hazard and needs to be handled accordingly. There are detailed instructions on how to handle it, which distil to pretty much the same rules as for molten candles. Fire-fighting advice is given, appropriate for large quantities - for us the relevant info is that it will need to be extinguished with foam or CO2; water won’t be appropriate. The flashpoint is 240°C, well above anything we’re going to reach in our processing.
The rubber material we used is made by Smooth-On and distributed in Germany by KauPo. It’s a two-part silicone called EcoFlex 00-30.
The datasheet is here (in German)
The recipe is simple: mix equal parts A and B, stir thoroughly without making bubbles, then pour into the mould and let set for 4 hours.
Safety considerations: basically it’s not recommended to get it on one’s hands, and otherwise work in well-ventilated areas. Wear the usual PPE, including some kind of eye protection. Wash hands after use (we’re doing that anyway thanks to the virus…).
The datasheet for this material is available online here
This is a two-part polyurethane specifically design for prototyping from a mould. It is said to flow well and its colour changing curing behaviour is useful for supervising the process.
Safety measures for the material are the usual: use in a well ventilated room, wear PPE, clean up spills quickly, and if possible, each component separately.
Mixing instructions included the ratio: 1 part A to 2 parts B, by weight. Both parts should be degassed for 15 minutes in the vacuum chamber before use. They should be mixed under vacuum, but a slightly higher pressure (20-25mbar) is recommended to reduce foaming. The pot life of only 5 minutes makes all of this rather exciting, and demands good preparation of the process steps, equipment and workspace before the mixing takes place.