After the
surface coating has cured, we move to building containers for the silicone rubber mold.
I bought poly foams with paper coating from Art friend and cut them up to build the containers.
Used masking tape to seal the edges
Using Araldite epoxy adhesive, we secured the 3D forms to the base of foam containers.
I bought 2kg of silicone rubber from Wee Tee Tong Chemicals. Grant helped me to add the hardener and mixed it with a power drill.
Pouring the silicone rubber into the containers.
Waiting for them to cure (about 1 day). We ran out of silicone rubber for the left one and to save time, I was tasked to buy Plaster of Paris to fill up the remaining after the rubber is cured.
After 24 hours, the left one managed to cure but the right one did not (it eventually took 4 days to cure omg)
Adding the Plaster of Paris mix, it takes about 30 mins to an hour to dry
Once the plaster is dried, we peeled open the container
Grant cut open the mold and established a parting line in the middle, but not all the way down
He made sure to carve a few registers on each side. Registers are basically the catches that help both sides align precisely to ensure accuracy and consistency.
The silicon rubber was insufficient for this (left) so unfortunately a hole appeared when we peeled the 3D print out. We managed to fix the tiny hole using the Alradite epoxy adhesive.
Using masking tape to secure the parting lines so the resin won't leak when we pour. I also had to cut and prepare acrylic tubes that I got from Art friend to insert after resin pour. The acrylic tube is to accommodate the LED strips.
Taped one end of the acrylic tube with scotch tape and jammed the opening with a chopstick and masking tape to make sure the resin pour don't enter.
I went to get epoxy resin from Wee Tee Tong but unfortunately I was given polyester resin in the end. I was only informed when I passed Grant the resin. The good thing about polyester resin is that it is much clearer than epoxy resin, epoxy resin tend to be yellowish when cured but polyester resin is bluish clear - resembling glass. The downside of polyester resin is it is even more dangerous than epoxy resin. Epoxy resin has a higher density and is more sticky while polyester resin is watery-like, which means I have to be even more careful when stirring so as not to spill any on my skin. Grant also mentioned that it is also more toxic and the burn enters the blood stream a lot more quickly compared to epoxy resin. I am really terrified but I'll try to be more careful under Grant's supervision. I also prepared different sizes plastic containers from home for the resin mixture.
After mixing the hardener into resin and stirring the mixture for a good 1 minute, the ratio for polyester resin is 1% hardener, we placed it in a vacuum chamber to remove air so that the mixture is bubble free.
We repeat the vacuum process several times to make sure all bubbles have disappeared.
As the container is quite large, Grant used masking tape to create a cone-shaped mouth so that the resin pouring is easier.
After resin is poured, we secured the acrylic tube with a wood block and placed it over the silicone mold to make sure that acrylic tube is centralised and it doesn't move about.
Now we wait for the resin to be cured, which takes about 24 hours, till the next post!
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