Recipe 13 : Foam Latex Prosthetic
- Koji Ohmura
- Nov 18
- 6 min read
Another special effects cooking time! This time, we are going to use a mixer and an oven. It is like making a bakery. Of course, you cannot eat it! But when it comes out of the oven and you open the mold, the feeling is amazing. It always reminds me of cooking in a restaurant kitchen back in my hometown. Yes, I was once a cook before becoming a makeup artist.
Recipe 13 features how to mix foam latex ingredients and make prosthetics. If you want to learn how to make molds, please check Recipe 1 (Lifecasting), 2 (Face Mold), 3 (Sculpting), and 4 (Mold Making).
Materials you need...
99% Alcohol
Gloves
SC Johnson Paste Wax (Furniture Wax)
GM Foam Latex Kit (Or any other foam latex kit)
Scale
Sunbeam Mixmaster (Recommended)
Convention Oven (1970s Farberware Oven is a good size for a face mold)
Oven Thermometer
Chip Brush
Baby Powder
Simple Green Soap
Material links are here.
Lesson Video
Mold Prep
In this recipe, we will use an Ultracal mold. (If you are using a non-porous mold such as fiberglass molds, 1630 molds, or silicone molds, please make sure to adjust oven time and temperature.)
If this mold is a fresh mold, put the closed mold in an oven for 2 hours at 180 degrees Fahrenheit. You need to dry out all the moisture inside the mold. Wait until it cools down before opening the mold.
Then, I will drill holes in the positive mold. These holes will help the extra amount of foam latex to escape when I pour foam latex into the mold. This process makes the cutting edge very sharp (better blending edge). The positions of the holes should be at least 1/2 inch away from the cutting edges.
These holes also help moisture to escae while cooking in the oven. Clean the mold with 99% alcohol. Check if there is no clay residue.
It is a good idea to set the AC at this moment. Foam latex does not like either high temperature or high humidity. (I like 73 degrees Fahrenheit & 30% humidity.)
Now, take a small amount of furniture paste wax and mix it with 99% alcohol. Brush this on both the positive mold and the negative mold. Let it dry for a couple of minutes. Then buff it with a towel.
Brush it on the entire mold. Next, brush on GM Foam Mold Release (Stearic Acid) on both molds. Let it dry and buff it off.
When it dries, it becomes powdery.
Mixing Foam Latex Materials
In the video, I weigh out 2 1/2 batches of Foam Latex. (For 1 batch, please follow the product's instructions.)
You will need...
A bigger bowl for 2 1/2 batches. (For 1 batch, you need a small bowl.)
375 grams of Foam Latex Base
90 grams of Foaming Agent (This is more than the regularly instructed amount.)
40 grams of Curing Agent (This is more than the regularly instructed amount.)
You can add extra agents if needed.
It is recommended to write down the formula for each session. This will help your future experience. I have all formulas since the early 2000s.
Shake the bottles well before weigh out.
Set a bowl of mixture in the Sunbeam Mixmaster. If you can't find it, use any other mixer that can adjust the speed. Do not forget to turn the vent on. It stinks really bad.
Speed 2 for 1 minute - This is for mixing all the agents.
Speed 12 for 2 1/2 minutes - This is for whipping. I use my hand to do back spins. This will make it easier to whip.
Back spinning to whip latex faster. Speed 8 for 1 minute - Refining time.
Speed 4 for 5 minutes - Ultra refining time. I move the whipper wands to the center sometimes to break bubbles.
Mix the center as well. Speed 2 for 5 minutes. - De-Ammonize time. Check the smell once in a while and see if you do not smell ammonia. That is the time to pour the Gelling Agent. Set a mold closer at this point.
Keep the mold closer to the mixer. Speed 2 for 30 seconds - Pour 37 grams of Gelling Agent while spinning the bowl. Within 30 seconds, pour this with a steady pouring speed. Do not dump it in the mix. You do not want chunks.
Do not dump it! Speed 2 for 30 seconds - Use a tongue depressor to scrape the foam mix from the side of the bowl. Slide the whipper to the center to make even mixtures. Back spin slowly. Work quickly!
The side of the bowl and the center tend to have unmixed latex. If you are using one batch mixture, the speed will be Speed 1, Speed 8, Speed 4, and Speed 1. Adjust the time accordingly.
You can also check the softness by picking up a small amount of latex while mixing. Use a tongue depressor. See the picture below. This will be the softest you can go. If you surpass this softness, it might create double-layer skin on the edge, cell collapsing, chunks during gelling, gelling too fast, etc.
Very soft consistency
Pouring Foam Latex mix into molds.
After 30 seconds of mixing the gelling agent, you will need to work fast.
Take a small amount of latex from a bowl. Brush it on a negative mold. This process will allow the latex to grab onto the texture details. When you brush it on, do not tap. Imagine that you are laying the latex on the mold gently. You do not want to create surface bubbles.
Brushing on skin textures. After you finish getting all the details, pour latex into the mold from the side. Do not dump it in the center. Rock the mold and slush the latex around. (If you feel that it is not flowing well, reduce whipping time or consider adding "Flow Increaser" to the mix next time.)
Let the gravity help your work. Place the negative mold on a soft floor mat, and tap the mold gently. This will help bubbles to pop. Do not tap on a concrete floor.
Pour the rest of the latex on the positive mold.
Don't forget to pour on a positive mold. If you see any bubbles, blow air and let them pop.
Close the mold with steady pressure. Do not pull it out; otherwise, it will create bubbles.
Steady, steady... Place weights over the mold and leave them on until the latex has gelled. Gelling time is preferred to be between 5 minutes and 15 minutes. (If it is too long, that means you have too much ammonia. Add more time to mix next time. If the gelling time is more than 15 minutes, cells might collapse.)
Extra exercise time for you!
Oven
Once it is gelled, remove weights from the mold. If you are using a mold strap, leave it on.
Prepare a conventional oven. Do not use a kitchen oven. Latex will have a toxic fume and you will not be able to use the oven for cooking food anymore. 1970s Farberware Convection Turbo-Oven is my favorite. It is slightly bigger than regular ovens from stores and holds a face mold. You can find it on ebay.
I also place an oven thermostat inside.
The thermostat is important for an old oven. For this mold, I set 180 degrees Fahrenheit for 4 hours. If you are using a non-porous mold, set the oven at 135 (or lower) for 8-12 hours.
Then, Pray to the Foam God.
My Foam God... It is an inside joke for our industry. Keep all your formulas, times, and experiences on your log. It will help your future experience.
Opening Mold
Wait until the mold cools down.
Place 2 x 4 wood pieces on the mold like a bridge. (If your mold does not have a bar or non-bucket mold, use a minus-shaped screwdriver.)
Use a mold clamp and hang it on the bridge and a bar. Twist the clamp handle slowly and open the mold.
A bridge and a clamp. Wasn't it Dick Smith's idea? Use an atomizer and spray baby powder into the mold. This will prevent the freshly cooked latex from sticking to each other while opening.
Atomizer is useful besides hiding your bald spots on your head! Open more slowly. Try to keep the prosthetic on one side of the mold.
When you are opening, check the edge often. You do not want to rip the edge.
Keep the prosthetic on one side of the mold. Powder the entire prosthetic piece. Let it set on the positive mold again for storing.
(Optional) You can wash the latex with soap (I use Simple Green) if you like. This will stop the latex curing process. Sometimes, the curing agent is still active and makes the latex harder over time. Also, washing will clean extra sulfur to reduce skin irritation.
No Bubbles, no ripped edges... perfectly done!!
Making foam latex prosthetics is very difficult. However, when it turns out great, it is very satisfying. It is almost the same feeling as when you see pastries in the oven. I love making foam latex more than silicone or any other materials. Even if it does not come out great, do not worry. The next blog will be about fixing foam latex prosthetics. Stay tuned!
Featured Items
DISCLAIMER: Links included on this page might be affiliate links. If you purchase a product with the links that I provide, I may receive a small commission. There is no additional charge to you! Thank you for supporting me so I can continue to provide you with FREE content each week!
Comments