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Getting ready for my first casting. Advice?

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Getting ready for my first casting. Advice?

Postby blacksmithn » Tue Jul 21, 2015 9:48 pm

I am preparing to cast resin for the very first time this coming weekend. I will be using a two part silicone rubber mold. I will be attempting to cast a 1/87 railroad flat car, so it will be a long (approx. 9 inches) and relatively narrow (approx. 2.5 inches) piece. I have viewed a number of Youtube vids on poured casting, which make the process look fairly (and deceptively, I suspect) simple. Any advice would be helpful. I have heard about using a syringe to inject the resin, which supposedly reduces air bubbles, but know nothing about the technique. I've also seen molds being dusted with baby powder or talc before casting, which is supposed to draw the resin into the detail. Is this a good technique? Do I need to use a mold release and, if so, what should I use? Most importantly, what do you wish somebody had told you before you cast your first mold?
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Re: Getting ready for my first casting. Advice?

Postby RageofAchilles » Wed Jul 22, 2015 6:23 am

Hi,
well I would say that the best thing somebody could have told me when I first started out was to have a good sized vent for the air to escape and a separate pour gate to one side of the model, with a channel that runs down beside and then under the model so that it fills from the bottom ( pushing air out as it rises.)

The other best thing someone could have told me was how to set up a Vacuum and pressure casting kit, but that involves some investment and is not to be undertaken lightly.
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Re: Getting ready for my first casting. Advice?

Postby mangozac » Wed Jul 22, 2015 8:16 am

Your first casts will be far from perfect. I wish someone would have told me just how deep the rabbit hole of learning to cast goes! :P

Appropriate venting is very important. For a part that size I wouldn't screw around with a syringe - it will be too slow for a part that size. Mould release is only necessary in a production environment and things will work fine without it. Talc is a good thing to use though as it will help pull the resin into details - just make sure it's a light dusting, otherwise it will obscure detail and have the opposite result!

As I said in my first paragraph though, manage your expectations. Without vacuum and pressure casting equipment you are not going to get perfect copies. There are definitely techniques to try to get improved results at room pressure, but there will still be an upper limitation.
Oh yeah I can make that....
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Re: Getting ready for my first casting. Advice?

Postby blacksmithn » Wed Jul 22, 2015 8:03 pm

These are excellent tips. I'm glad I asked. I realize my first casts won't be perfect-- especially given my misadventures in mold-making! I'm shooting for "good enough" but recognize that my inexperience with technique may preclude even this standard. Still, as with the mold, it's a process to be learned through experience. As a great artist once said-- the sooner you make your first ten thousand mistakes, the sooner you can correct them!
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Re: Getting ready for my first casting. Advice?

Postby mangozac » Thu Jul 23, 2015 7:36 am

Very true! Keep us posted on your progress!
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