Tutorial: How to Cast Foam Bases + Tips

How to make cast foam bases by TinyFox aka TinyBadger aka bitey shark aka Glitzys Assistant
The base shown is a Sere Studios Base! I did not have one of ours handy and as a rule we do not show ours un-taped.

PREPARATION:

Safety:

Now first things FIRST THING F I R S T T H I N G first :D ALWAYS wear gloves and a mask/respirator when working with any kind of chemicals, especially powders or things that foam or give off an odor when reacting safety first.

Do all of this in a well ventilated area and wear gloves 

Necessary Materials: An in depth look at what materials to buy is here.  

Recommended: Clay, Tape, Vasaline. Some clothes you don’t mind ruining, An assistant that’s really sexy and good at making tutorials, Acrylic paint

FINDING OR MAKING A BASE TO CAST

What you’re going to want first is a base to cast. If you’re good at digital sculpting or with permission from another maker you can 3D print one, and if you want to go rouge sculpt one out of clay

DO NOT cast another makers base without their permission. They can literally sue you and it is SUPER frowned upon

Always do a test patch with the silicon on substances youre casting over, some oil based clays make it so the silicon won’t cure.

Buying Silicone to make the Mold

For silicon you can use rebound 25 or dragon skin, but others are on the market. We buy our products here, but you can also find them on Amazon in trial sized units if youre just starting out. 

Smooth cast 30 (or oomoo silicone) is trash and tears easily, do not use it 

Corn starch can be mixed with you silicon as a filler, but always test amounts.

A proper casting environment is average humidity and temperature. Please refer to the instructions on the box as they will give you a proper humidity and temperature to work in. These materials are expensive, you do not want to waste them.

MAKING A SILICONE MOLD

Start with your base on a flat surface that you don’t mind getting a little messy

You can build up a ridge with clay or tinfoil to catch access silicon or live on the edge like I do

Mix your silicon as the packages tells you to and pour your first layer. It’s going to be very liquidy but that’s good because you don’t want any gaps in this first pour. Make it even and cover the whole base

Pour it Over the Base laying flat on its back.
Try to get this as even and thin as possible to preserve the details.

Wait for that to dry, the exact time will depend on what you bought.  Dragon Skin FAST is what GFS uses, and we love it. 

Once dry, time for another layer! 

On my next coat I like to add some acrylic paint to it to see how thick the silicon is getting and I add some thi-vex to the mixing cup and wait for it it activate

This makes the silicon much easier to work with and allows you to really focus on thinner areas

Repeat this process until the entire base is covered in at least a half centimeter of silicon, you can measure this by pushing a needle into the silicon and marking how deep it is.

MAKING THE MOTHER MOLD

With the silicon mold done it’s time for the mother mold.

Take tin foil and build up a ridge down the middle of the silicon, this is where our two pieces of the mother mold will meet

Put a thin coat of Vaseline (or chapstick if you’re in a pinch) over the silicon for this next step

Time for plaster! Take some shop towels and cute them into strips. soak them in a cup of water and mix up plaster of Paris with a biiiit less water than instructed in a separate bowl

Dump your towels in the plaster and cover your mold with the strips (plaster strips also totally work for this.) keep it as close to the base as possible and make sure not he sides of your towel strips are well saturated.

It should only take one coat but if it doesn’t feel thick enough add another

You can also smooth some more plaster over the towels to get a nice finish and added strength. Fill any gaps with more plaster

Let those sit until firm

You can cut the mold in half if you need to get your silicon in easier or release the heads easier.

CASTING EXPANDING FOAM BASES (MAKING A BUNCH OF FOAM BASES)

Now to the casting!

You can use these molds for flex foam or resin, but this tutorial will specifically focus on flex foam. the products on the market vary a lot and each will change the outcome of your projects, so do some research and always cast in a well ventilated area

Spay down your mold with some de-molding spray and let it sit for about 8 minutes, you can mix your flex foam in this time

Wear a Respirator and then Mix your flex foam according to instructions and pour it into the mold. It should poof up enough to cover all the parts of the mold. It expands to about 10x the size. 

I haven’t mentioned any measure to because it’s is very dependent on the size of your base but half a solo cup for part a is perfect for our larger bases.

As its expanding, do not touch it, do not push it down even or you sill stop the reaction.

With that done give the flex foam a chance to cure accounting to the box directions and you have a head base! (Note after 2 hours it will be good to "pull" from the mold" but we typically give them a full 24-48 hours.