Week 12: Moulding and Casting

Tasks
- Review the safety data sheets for each of your molding and casting materials
- Make and compare test casts with each of them
- Compare printing vs milling molds

Material Data Sheets

Wayin UV Resin

Safety Considerations made from reviewing safety data sheet:
- This resin is non-toxic but is still hazardous if ingested or comes in contact with eyes.
- Eye contact can cause irritation. Rinse eyes with water for several minutes if contact occurs.
- Ingestion can cause abdominal pain and discomfort. If ingested, rinse mouth and do not induce vomiting. Seek medical aid immidiately.
- Wear protective gloves and safety glasses when working with material.
- Do not eat, drink or smoke when using this material.
- Fumes also present an irritation risk, use in a well ventilated area.
- Fully cure any tools or items that come into contact with resin before disposal or storage.

SiliCreate Fast-20 Silicone Rubber

Safety Considerations made from reviewing safety data sheet:
- In rare cases skin contact can cause an allergic reation, if contact occurs wash thoroughly with soap and water.
- Contact with eyes can cause irritation. If contact occurs immidiately rinse eyes with water, seek medical advice if neccesary.
- Ingestion can cause mild irritation, do not induce vomiting if swallowed. Consult medical aid immidiately.
- Do not eat or drink when using this product, always wash hands before breaks and at the end of work.

Pebeo Gedeo Light Plaster

Safety Considerations made from reviewing safety data sheet:
- Material is alkaline in nature and can cause mild burns to eyes skin and mucous membranes.
- Ingestion can cause mild burns, if swallowed rinse mouth, do not induce vomiting and seek medical advice.
- If eye contact occurs, rinse eyes immdiately and seek medical advice.
- The dust of this material can be a severe respiratory irritant, a dust mask should be used in prolonged exposure.

Testing and Comparing Moulds

To start with we tested the resin in a small mould that we pre-purchased.

We poured in some clear resin straight out of the bottle, and also poured in some that we had mixed with green dye. We tried to create a little swirl of different colours. We then popped it under our little UV curing station and did some tests on how long it took to set. We found that it took a few minutes longer than the advertised cure time, but it was still under 10 minutes. And this test piece came out really nice without any issues. This test was without any release agent and we found that it was fine without it. It might reduce the lifetime of the silicon mould, but for low number productions it should be alright.

We also performed a test cast with the plaster Liam was using. We mixed the plaster powder and water as directed and it turned into a runny paste. It was so runny that we thought we might of messed up the ratio, but we left it in the little paper mixing cups we were using to test the cure time of it (and also the spoon for a laugh).

There were several ways to speed it up but we opted not to and wanted to see how long it would take compared to the advertised 1 to 1.5 hours. It was a very cold winters day here in Australia so this would put it onto the longer end. We tested it at 1.5 hours and it seemed to be cured enough to be removed. It stuck really badly to the paper so we peeled it away, but it was nice and solid (although a bit more brittle than expected).

And finally we tested the silicon. To do so we killed 2 birds with 1 stone and tested it in our FDM printed negative to make a silicon mould. We mixed the silicon as instructed (50-50 by weight) and poured it into the 3d printed mould (while using vaseline as a release agent.).

And after the "incredibly quick" cure time of 30 minutes, we found that it was still not fully set. It had definitely skinned over but parts of it clearly hadn't set. We might of mixed it wrong, but it took about 90 minutes to fully cure. After that wait though, it came out of the mould easily and was ready to be used.

Printed Mould

For our printed mould we made a small pot for Liam's project. It was meant to be a 2-part mould but time constraints forced it to be a 1-part. We started by designing the mould exactly as we did for the wax mould.

Then we went ahead on our Bambu A1 (which makes these cool timelapses).

And then as spoilt before, we applied release agent and poured in some silicon to make our mould from it. After letting it set, we pulled it out and as a testimate to the detail captured by the silicon, saw print lines galore in the mould. We tried to layer on the vaseline thick to try and fill in some of those print lines, but a lot of this was in vain.

And then we went ahead and cast some green and purple dyed resin. We then took it to our resin 3d printing curing station as it had some stronger UV leds in it, and even with the extra UV strength, it took a great deal longer to cure - about 20 minutes. Maybe it was because the silicon mould was extremely thick in some areas, maybe it was because there was too much dye in the resin.

And after popping out the final piece, it was alright... except for all those print lines. Every single print defect and line from the 3d printed negative had transffered over to the final piece. Meanwhile our wax-milled blocks produced buttery smooth pieces with smooth curves.