Casting is one of those things that becomes massively ‘addictive’. I’m not sure that is the right word, but once you’ve successfully managed to mold something the feeling you get after pouring and revealing your first cast is such a buzz!
In this article I cover the fairly simple process I follow for casting bases in a gang mold.
First I make sure I have good space around me and good table space, nothing worse then working in a cramped space.
Step 1 – talc
Select the molds and grab some baby powder, using the brush apply a generous layer and brush into all the cracks. You probably don’t need to use as much talc as I did in the photo, however, its cheap and easy to get so I don’t worry to much.
Once I have brushed the talc around, I turn the mold upside down and firmly and sharply smack the bottom of it to remove any excess/lose powder. What you will end up with a very thin layer of talc covering the silicone. This helps break the friction between the silicone and the resin allowing the resin to flow into all the details more easily.
Step 2 – weigh
With my molds talc’s and ready, I get my scales, mixing container, stirrer and resin. I also like to use some black ink (specifically for polyurethane resins) and you can see that in the picture, the little black bottle.
Step 3 – mix
With my scales and resin ready for mixing, I place the mixing cup on the scales and reset/tare it, this sets the weight to zero, making sure I am only weighing the resin, not the cup also.
I then estimate (or use a reference card if I have one) the total weight of resin required to fill the pieces I want to cast … in this case I guessed around 90 grams. I tared the scale and poured 45 grams of Part B – I have found no difference in the order of which you add the resins.
To the resin in the cup I then add a few drops of the black ink. The resin naturally cures white, by adding black dye you will end up with a grayish piece. The more ink you add the darker the pieces will be.
With the first part poured I then re-tare the scale, setting it back to zero. I know the first part weighs 45 grams so I pour in 45 grams of Part A and get my stirrer ready to give it a good mix.
Step 4 – pour
It’s time to act quickly and I dont have the time to try and take a picture whilst I’m pouring! Now that the two resin parts have been mixed the resin will start to heat up and cure. I mix my resin until I can feel the cup starting to get warm, from there I have less then a minute to pour the resin. Depending on the temperature conditions the time can vary, but the longer you spend the thicker the resin will become as it cures.
I pour about half the resin I need into each piece before coming back to ‘top’ them up. This allows the resin more time to find gaps and makes it easier when I kneel down at eye level with the mold and drop-by-drop fill each base until it is flush with the surface of the silicone.
Step 5 – wait
Now the resin has been poured into the molds we need to wait. The type of resin you use will determine how long you need to wait for the resin to cure. Easy Cast has about a 20 minute de-mold time. I missed out on taking a picture of the resin part-cured, but you will notice the resin turning gray (or white if you did not use ink to colour it), generally from the deepest part of the mold first.
Once the resin has cured you can de-mold the pieces and set them aside to fully cure. Depending on the thickness of your mold you will be able to flex it to help remove the pieces, I usually flex it and push up underneath each piece with my thumb or finger.
Step 6 – profit
Congratulations! You now have new casts from your mold. Rinse and repeat until you have the desired number of bases.