This was supposed to be in my figure thread, but I left it here too as it seemed a fitting conclusion.
All pictures are thumbnail link to larger photos.
Making Pewter Miniatures From RTV Molds (Part Three)
Welcome to part 3 of creating RTV molds cutting molds and casting the pewter
All the molds are set. Now I get out a new hobby blade and start cutting v-channels in the molds to create paths for the pewter.
As I cast the figures I will continue to cut the molds to get the best flow possible. The next step is to cut a pour funnel. This proved to be very difficult with the smaller molds – more on that later.
Each mold has talc powder brushed in it to help separate the molds when the pewter is poured.
The next step is where my wife calls me a fool. I do not own a mold box or mold clamps. Instead, I cut bass wood to match each mold and then clamp the molds with old fashioned rubberbands. Why does my wife call me a fool? Well, if I miss pour the pewter the bands will snap and I could get a lap full of pewter. In other words, don’t do what I do – buy a mold box and some proper clamps
Here’s the work area. I have a nice big piece of ceramic tile on top a huge piece of oak. The hotpot is full of scraps from previous projects and the molds are ready to go.
Now the hotpot is plugged in and the pewter melts. There will be some impurities floating around the top. I scoop these off with an old stainless steel spoon.
I pour the first batch of molds and it becomes obvious the small molds have a problem. I can tell the pewter is not really going into the molds. Looks like some more cutting is in order…
I pop open the nyrf armless wizard mold and things look pretty good. Forgive the heavy flash, it was in a poorly lit area.
Next, I open the D’karr wizard and immediately notice a small tear in the mold due to an undercut on the figure. The figure looks pretty good though.
Shape D.’s mold was next and the entire length of it ripped – an undercut on the cape pulled the whole thing apart. Damn… Well, I got one mediocre figure out of it – the mold really was not hot enough, but it will have to do.
RTV can be a catch-22, use a flexible mold that can handle more undercuts and it cannot handle high temperatures – use a high temperature RTV and it cannot handle many undercuts. I have to use a fairly high temp RTV, because I use lead-free metals - Too many kids about the house to do otherwise.
Here’s the final figures I selected for shipping. The strange looking orbs at the bottom are supposed to be my Flaming Sphere markers. It looks more like – in the immortal words of my wife ‘A mutant bowling ball.’
So I packed the figures up and shipped out the boxes today. I decided to throw in the molds so you folks could check them out. I think the best cast figures of the bunch by far was Nyrf’s wizard’s assistant robotic arm. I cut and cut the small molds, but I could not get the pewter to flow down them. I finally gave up around 2:30 AM. I think for pieces that small you have to have a spincaster.
So here’s what is heading your way via priority mail:
1. Your original green – or what’s left of it.
2. The molds I made from your figures. D’Karr’s wizard mold is badly ripped as is Shape D.’s, but nyrf’s molds are good to go for more casts.
3. Everyone received an armless nyrf wizard and robotic arm assistant, a D’Karr wizard, and a mutant pogre flaming sphere marker. Shape D. also received the only cast I got out of his figure’s mold.
I hope you are not too disappointed in the results. I think next time I will set up a guide for sculpting to allow more successful casts. I did not consider all of the undercuts figures’ might have before the project started. I also learned small/tiny pieces just do not seem to gravity cast very well.
