Thursday, December 22, 2011

Extra Tiny BJD Project: Part 5

It is finally time to make some silicone rubber molds of my little bjd reindeer. I had recently made my pressure pot, so I get to finally use it.

The inside of the pressure pot is concave, so I placed what seems to be an old pie pan inside the pressure pot.  The inside of the pot is about 9.5" an the pie pan is 9".  Pretty good fit.  The only problem is the bottom space of the pie pan is 7".  So the space is rather limited until I use something else.  I also made sure the bottom was level.  (I did remove the little device after I had it centered.)

The first molds being made are for the head and all the legs.

Here is the head mold.  It is hard to see all the details, but she is facing up.  Her head will require 4 molds.

The back limbs were a little tricky because of the slot on the upper leg.  You can just make out the slots on the front arms with 2 vents to make sure air doesn't get trapped.  I was going to make a 1 piece mold and cut it apart, but I will be using OOMOO 30 which won't be easy to see through.

I did purchase Dragon Skin 30, but now is not the time to test it out.  OOMOO 30 only takes 6 hours to cure and Dragon Skin 30 takes 16 hours.  I don't have 16 hours to leave molds in the pressure pot.  I only have until Christmas morning to finish casting 5-8 resin dolls.

In case anyone is interested, here is my math in calculating how much OOMOO 30 I needed of A and B by weight.  First I figured out the dimensions of the inside of the mold box.  I needed to know also how tall I was going to pour the silicone rubber before I can calculate the cubic inch of space that the silicone rubber will be poured into.  I was able to figure out how much said cubic inches weighed in pounds which was converted to ounces.  I had to then calculate how much of part A and B is required by weight.  (Some of the above information is located on the product sheet and more detailed instruction is located on one of my previous posts.)  The high range number is how much silicone rubber is needed if I was pouring a solid box, which I am not.  There are parts that subtract space from the silicone rubber, so I estimated that portion to be 1 cubic inch.  This helped me calculate a low range and then decide what mid range value I would use.  This will reduce waste but ensure I had enough rubber to fill the molds.

I decided to use a gram scale for the measurement so I had to convert my numbers.  I ended up pouring 56.7 grams of A and 70.9 grams of B.  It was the perfect amount of silicone rubber to fill my molds.

Once I poured, I put the molds into the pressure pot.  I put 55 psi of pressure into the pot and am just letting it sit for 6 hours.  Now I need to make mold boxes for the 3 body sections.

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