I still consider myself an “average Joe” to molding and casting even though I have a few years of experience under my belt now. Since I have been working on creating some casting kits lately, I thought i would snap a few pictures along the way and explain my process of molding and what it takes for me to be successful enough to produce most of the parts that you see on a regular basis.
The key to what I have learned by trial and error is to make sure there is a plan even for small projects as simple as a single head mold to cast. I don’t make many 2-part molds hardly anymore because of the excessive clean up that goes along with it a lot of times. So I have been doing slit-line molds for quite some time and have been tweaking my technique of making them by asking myself “which way gives me the best detail and less mess approach on the casting itself?” “How do i pour the resin? How will the part sit in the silicone and be able to reduce the air pockets when resin is poured into the mold? I’m all about trying to make my life easier with this hobby by being able to produce parts in a shortest amount of time and light on any clean up as much as possible. When I start a molding project, I usually mold in stages. About 3 stages will do. The biggest mistake that can be made is to try and rush through because it would cause even a bigger headache later on which may result in wasted time and material and having to start over again.
Here is a pic of my stage 1 and prepping for stage 2 of the molding process. the mold box on top starts it with a silicone floor. I pour about 1/8” of silicone into the box and put it into the pressure pot to push aout any air bubbles. this will give the parts a floor to sit on. the box below it shows how I plan the parts to sit and also using some silicone scrap blocks to help hold the master parts in place. I make sure any high points of the parts are facing up because the bottom of the mold is actually the top when completed.
Stage 2 is actually pouring in some silicone without completely covering the parts because if the box was filled completely, the parts would float in the silicone and move. I’ll position the parts in the box like planned out and then placed into the pressure pot to push out air bubble in the silicone.
Stage 3 is when I pour silicone into the remainder of the mold to finish it off. If by chance I notice any air bubble in the silicone, I’ll use a syringe to inject into the holes first before pouring in the last bit of silicone. Then place it into pressure pot again.
Each stage time is about 2 hours or so to cure completely depending on the size of the mold. larger molds take a little longer to cure.
Making the molds with plenty of silicone area around the parts is the best way to go for the durability and longer life of the molds. I have tried cramming in more parts into mold boxes that gives me a harder time when pouring into the molds.
Now, that the molds are complete, I’ll pop them out and turn them upside down and do surgical slit lines for each part. the Robin mold will be cut away from the arms because the slit on the torso will go across the shoulders instead of it back. the arm mold slits will be underneath because it would be less obvious to see than on top of the arm. giving them all face value parts.
Now all I have to do is open the molds up and pour resin into the molds to make the casting duplicates. I will sometimes use my resin stir tool to help push liquid resin into some tougher areas of the molds to make sure air bubbles don’t develop. works most of the time but not all the time.
Now I just inspect my first castings from the molds to find out if their are any defects in the molds that I didn’t catch or find troubled air bubble areas that I would need to adjust my pouring technique or push out with my tool or maybe have to use the pressure pot to force the air bubbles out.
Overall, these molds were a success in my book. the finger tips on Aya didnt turn out so good but thats to be expected with and area as narrow as 0.05″ to try and get the resin in but still fixable. the rest of the parts turned out really well. not all molds, due to their shape, do as well as this but I still pretty much keep the same process.
Time for me to get back to casting and I hope everyone that pre-ordered these kits will be happy.