Intro: Lifecast With Silicone
Lifecasting is the process of making a mold of a living human body.
There are a variety of techniques and methods that can be used for lifecasting.
Types of lifecasting materials include; plaster, alginate, silicone, and sometimes even waxes.
In this case, we will be making a mold of a hand using silicone and a plaster bandage mother mold.
Step 1: Gather Supplies and a Model
Fist step to making your lifecasting is gathering supplies and a model.
It is advised that you do not attempt to make a mold of yourself because it will be difficult to maintain your mold posture while applying mold material and waiting for it to cure.
If you'd like a mold of yourself have a friend help you, or make a mold of your friend instead!
If this is your first time making a mold you might want a third person on hand to help you as the silicone has a short work time and a second pair of hands will help things go more smoothly.
I used the body double starter kit from smoothon.com because it contains all the necessary supplies for making a decent sized lifecasting.
Remember to use a skin safe mold material. Not all silicones are skin safe and may cause an allergic reaction in the model.
It may be helpful to have all of these supplies on hand:
- plaster bandages
- one time use brush
- drop cloth
- release agent
- mixing cups
- bucket of warm water
- mixing sticks/Popsicle sticks
- small mixing container
- chair for model
- Mold making assistant
Mold making is a messy process. Put down a drop cloth before you start and make sure you and your model are wearing a smock. I've ruined too many outfits making molds.
Step 2: Make a Test Patch
Have your model apply the mold release agent to the area you will be molding especially if there is hair present. This will help keep their hair on them and not in the mold.
Before you mix up a whole batch of silicone start with a small teaspoon amount to use for a test patch.
Although this is a skin safe silicone, everyone is different and it's a good idea to make sure your model won't have an allergic reaction to the silicone before their body is covered in it.
Mix a very small equal amount of parts A and B in a small mixing container.
Apply this mixture to the area that will be molded and wait a few minutes. If there is no allergic reaction you're good to go! If there is, wash off the mold material.
Step 3: Add Silicone
Now that you're sure your model won't react to the materials you're using, mix up a larger amount of silicone for your first mold layer.
The body double silicone has a convenient one to one by volume mix ratio.
This is a fast curing silicone so don't mix up a huge amount or it may cure before you have time to apply all of it to your model. Mix up just enough to get down your first thin coat.
I find using a brush for the first coat is the best way to capture all the details.
Make sure your model maintains the desired posture through out this process, the silicone will begin to cure by the time your first coat is done. It will get thicker and emit some heat during the curing process.
While the first coat is curing start mixing up silicone for the second layer.
This layer does not need to be as precise and you'll be applying more material to build up a thick mold wall. You may find using a large popsicle stick to apply silicone is more effective.
The silicone will want to drip off of your model as your're applying. This is where having an assistant can come in handy. They can catch and re-apply the dripping silicone while you add new silicone to conserve time and materials.
Repeat this process until you have a roughly uniform .25" wall thickness throughout your mold.
Remember to apply silicone about an inch or two past the area you would like to make a cast of. This will make the casting process easier.
Step 4: Add Mother Mold
While your final layer of silicone is curing, start cutting up strips of plaster bandage to use for your mothermold.
I usually vary the sizes between 1" and 3" long.
Build the mothermold in two parts so you can release your model once it has dried.
Find the best orientation to part the mothermold in order to avoid undercuts that might trap your model inside.
Once the silicone has set, dunk the plaster strips in a bucket of warm water as needed and gently wring out excess water. Apply the wet plaster to the silicone mold while it is still on your model.
Start by building one side of the mothermold. Let this side set until slightly cured.
Apply release agent to the edge of the mothermold. (about .5" in) This will keep the two halves of the mothermold from bonding to eachother
Then apply plaster bandages to the other side overlapping with the first side on the areas where release agent was applied.
Step 5: Demold
Let both sides of the mothermold set until cured. You will know it is cured when it is no longer damp or cool to the touch.
At this point, release your model from the mold.
If they cannot be removed from the silicone you may need to make a small slit in the side. Cut in a zig-zag rather than a straight line and be careful not to hurt the model.
Now you're ready to start casting!
Step 6: Casting
Place the silicone mold back inside the two halves of the mother mold. You may want to hold the two sides together using a rubber band.
If your mold will not stand on its own, use something sturdy to prop it up.
Begin by gathering your casting materials.
I casted mine in Soma Foama 25
Spray a mold release into the mold (I forgot to do this and two of the fingers ripped off while releasing it from the mold!)
Measure equal parts by volume of A and B. Remember this foam will expand 2x it's size.
Combine A and B in a separate mixing container. When they are fully combined, pour them into the mold. Try to get the mixture into all parts of the mold. (The pinky finger on mine didn't cast because I didn't push the material into that part of the mold)/
Let the mold sit until fully cured. It will want to expand and push the mold out of shape so hold the mother mold together with tape or rubber bands.
Once it has cured, release it from the mold!
My cast didn't turn out as I has expected, here's some mistakes I made along the way...
- The hand's posture creates several undercuts which make it difficult to release from the mold.
- having the fingers splayed apart creates small areas that casting material needs to get into
- I forgot to add a release agent when casting
- I did not include enough extra mold material on the wrist area to assist in the casting process.
- The mother mold was not thick enough and easily deformed under the pressure of the expanding foam
- There was not good way to secure the two halves of the mother mold.