Tutorial: molds and Resin copies 1 part

This topic is published with the intention of giving useful informations to those that want to start using rubber molds and resins for casting figurines or other objects to be customized. I will take as a sample some characters from my collection of superheroes.

Today I was at the store to buy some resin to make a copy of some character.
I bought Sintafoam resin from Prochima, cost 13€. Let me see what I can do with 13€ of resin.

First of all I needed some mold for doing the copies. I use rubber GLS 50, from Prochima also, for my molds. It is expensive (about 35€ per 1/2 liter) but extremely easy to use, and with high performance in copying each single little particular from the original piece.

I already made at least 12 different molds of different characters, so I did not made it right today and used already prepared molds. By the way, in order to show you how I made molds here I'll introduce some picture.

Rubber is casted in boxes or cans obviously larger than the piece to be replicated.
Most of the people prefers 2 shells molds, that is they prepare the figure and cast the rubber at half figure. After hardening the rubber they cover the rubber and the figure with a slight layer of grease and cast the other side. The grease is used in order to avoid the permanent union of the two blocks of rubber. They use also to do some centering prick in the mold. this practise requires also the use of some dough and a double of the time compared with single shell molds. that's why I prefer single shell molds.

I use to stick with the glue 2 toothpicks at the two edge of the hands of the figure until they are beyond the base, to create in the mold vents of air from the hands to the upper outside of the mold.
This is due to prevent air bubbles remaining trapped into the mold while casting the resin inside.
If the air remains trapped it will result in missing part of the replicated figure. Typical of hands, nose and chin.

Preparation of the figure for the mold casting:

In the following picture the sticks aren't present, but  it is only to show how to fix suspended the figurine into the plastic glass before the casting:

Check there is NO CONTACT between the figure and the plastic glass! Otherwise you will create a channel leading the resin to go outside from that channel when casting the copy.
Choose a safe place where the stuff cannot be moved accidentally, it will harden for at least 8-12 hours (the hottest the ambient the fastest the hardening).
Now mix the two components of you rubber (rubber itself and hardener) at least for 5 minutes. When you approach more resistence from the rubber, just cast it in the glass. After 12 hours take a cutter and gently start cutting out the figure from the rubber. Just cut ONLY the upper part (the side where you will insert the resin). The less you cut (until you aren't able to extract the figure from the hardened rubber) the best the copy will be, having less casting fins as result.

When I mold having in mind to cast from the feet (like the sample before) I cut at least from the feet to the stomach to be able to remove the figure. When viceversa I mold having in mind to cast from the head, I use to cut from the head to the shoulders. casting from head is easier to extract and give better results. But in this second case you will have to remove the figure from its base. That's why often I also cast from the feet, I' m lazy!

Try to do one line straight cut along the centerline of your figure! The less rubber you cut, the best is the copy later. And when you remove the figure from the mold don't forget to remove the toothpricks for air channels also!!

This should be the result (in the picture the sample is with crystal rubber) after extract the figure (of course with the figure inside the rubber):

 easy to move out from the glass

 well hardened and cut more or less at figure's centerline (vertically)

 And this is the cut made with a simple cutter directly on the mold when I extracted the figure :

Ok I hope I gave at least a idea on how to do it, whenever further informations will be required I'll be pleased to add in this first part of the post. Now let's go casting.....