10. Molding and casting¶
10.A Group assingment¶
10.A.1 Safety Data Sheets¶
I check the lockers at the fablab and found some materials that were dry due to they had not been well preserved or others that were out of date. So I look for a quick solution and considered to go to the vending machine that dentistry students have at their school.
In Safety Data Sheet you can find the following sections:
- Identification of the substance and the company that produces it.
- Hazard identification.
- Information about its components.
- First aids.
- Fire-fighting measures.
- Measures in case of accidental spillage.
- Manipulation and storage.
- Exposure controls / Individual protection.
- Physical and chemical properties.
- Stability and reactivity.
- Toxicological information.
- Ecological information.
- Considerations to elimination.
- Information concerning transportation.
- Regulatory information.
- Aditional information.
I choosed the following materials.
The only consideration with this material are the fumes generated when molted. It is being ask to do not breathe vapor from heated material.
It shows two hazard classifications and indications.
- Eye Irrit. H319
- Aquatic Chronic H412
It is also ask to not relive to the environment since it solidificates when it is mixed with water. So it is dangerous if it go to the eyes.
Finally I won’t be using it.
It’s SDS sais it doesn’t accomplish PBT or mPmB standards. Oh my God! But it is basically calcium sulfate as it is identified by its CE identifier. So will use it for the final pieces.
Link to two-component silicone SDS for this component sais it is an industrial product and it shouldn’t be used for alimentary moulds or in contact with the skin. So will be using protection gloves.
10.A.2 Casts tests¶
Cast test for alginate and plaster. I tried them as I was doing the mix for the mould. With the alginate the quantity of excess water was appreciable. The mix of alginate was drying faster than what it was refered. I was suposed to be usable for a minute and a half but it took arround 30 to 40 second to dry after starting to do the mix.
With the plaster I did not find any problem. Everything work as it was suposed to be.
Another thing I learned was to slowly add the powder to the water instead of doing it the oposite way.
10.B Individual assignment¶
10.B.1 Three parts mould. The cup¶
10.B.2 One part mould. The Rattleback¶
Since the test I did with the three parts mould were not succesful I decide to go for a simplier one part mould. To not waist more time I decided to use the concept design of the rattlebacks.
To not produce more silicone than the needed I really took care to estimation measurement before mixing both components.
VID_20190327_190759 from germancolomar on Vimeo.
For the same silicone I could took a 1.5, 5 or 24 hours catalyst. I got the 24 hours one. This one should be added in a 5% of the total mass needed. The following day a took it appart from the mould and applied a spray release agent. The ACMOS82-2405 you see in the back.
Considerations on the percentages of the mixture. Two parts of powder for one of water, this time.
A couple of hours later I could took them off the silicone mould.
Nowadays they become part of the FABLABUE.