Well I saw the picture to the right and thought it would be a fun build.So I started with a Dash hot rod body, a Dremel motor tool and some styrene. You can read about that here. While I was building the Rat Rod I started thinking of the different versions I could build. I couldn't come to a decision so I said why not do them all. That leads me to resin casting the Rat Rod.
First I clayed up the mold master on a clay pedestal.
After claying up the mold master, I take a Q-tip and clean the outside of the mold master. I remove all clay residue and possible finger prints. If any foreign material is on the surface, including finger prints, it will be transferred to the mold if not cleaned and removed. What this means is, if you leave a finger print on the mold master it will be transferred to all casts from that mold. When claying up the mold master take your time and work clean and careful. It is worth the extra time.
As usual I make my mold box. As you can see I use Legos.
Don't forget to put clay on the bottom before flipping over to prevent RTV from running out of the bottom.
Turn the box over and center the box around the mold master.
Once the box is set for the female mold, it's time to mix the RTV. The part A and part B is poured into two separate cups. Part A and part B are of equal measure by volume.
Next pour the part A and part B at the same time into a third cup and then stir thoroughly.
Once the RTV is mixed thoroughly now it's time to pour the female part of the mold. Pour the RTV in one corner. Pour slowly and pour high. This slow high pouring helps to eliminate bubbles in the RTV. The high pour and the small slow stream gives bubbles the opportunity to escape the RTV in the pour stream.
Here's a shot of the pour completed. Notice the bubbles are still rising to the top. I gently bounce the mold for about 30 seconds to help the bubbles rise to the top.
Since I pressure cast, I have to also let my mold cure under pressure also. If I don't do this then my casts will have small bumps all over them. See the picture below for an example.
So my mold goes in the pressure chamber too for about 4 hours.
Next I start preparing the mold master for the male part of the mold. I add the rods so that the pour and vent holes will be created when casing the male part of the mold. Notice the large rod in the center... that is where I will pour the resin into the mold. It is larger and it goes to the lowest part of the mold. This is done so the air in the mold will be pushed up and out the vent holes. The rods are styrene tube and rod.
Now the mold masters are in the female part of the mold and I am almost ready to mix and pour the RTV to create the male part of the mold. The last thing I will do is spray into the mold a coat of mold release before pouring the RTV. Notice I have the body and the top of the rat rod ready. I will pour both at the same time. Even though I have shown your just the rat rod body I have also repeated the steps to create the top that goes with the rat rod.
RTV for the male part of the mold has been poured.
Now back in the pressure chamber for 4 hours.
When the RTV is cured It's time to get the mold and the resin ready to pour. To get the mold ready I remove the mold master and then make little pour cones for the liquid resin.
Then I get my resin ready to pour and mix. The resin is a two part resin. I measure equal parts by volume into two separate cups and then pour those two into a third cup and then mix with a coffee stirrer.
Once the resin is mixed you will have to work quickly... the resin I use gives me about 7 minutes so I have to pour the resin, transfer the molds into the pressure chamber and pressurize the tank in about seven minutes. That said, I have everything ready to go before I mix the part 'A' and part 'B' resin.
First cast fresh out of the mold... it turned out fairly well for the first one I think.
Resin casts pieces cleaned and assembled...
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