Introduction: Silicone Rubber Sculpture Techniques
Silicone rubber is not a common sculpture material. It is sticky, puts off ascetic acid fumes as it cures, and you can't use your bare hands to work with it. This instructable is about various uncommon techniques I have developed to work with it.
Silicone rubber is normally used as a sealant for windows, etc. You can buy it in 10.5 fl. oz. grease gun cartridges at a hardware store for around $4, so it is not prohibitively expensive to work with. It comes in a limited variety of colors, such as black, white, brown and clear. I always buy clear silicone and colorize it myself with powdered pigments.
You can get some cheap powdered pigments that are used for colorizing cement at some hardware stores. A wider range of colors can be obtained from some art supply dealers. (Google search "artist powder pigments" for some online sources.)
Here you will find photos of some of my silicone rubber sculptures and brief explanations of how they were made. Most of the sculptures were built up directly. Others were made indirectly, using molds. The belly dancer below was a complicated piece made with several molds. I will explain it in more detail later.
Step 1: Silicone Rubber
I don't know the ecological side effects of manufacturing silicone rubber, or its eventual decomposition. When cured, it is non-toxic. It comes out of the cartridge as a sticky paste, smelling of ascetic acid (vinegar), and it cures fairly quickly, turning into a rubbery substance.
It sticks like crazy to some non-porous materials, like glass, metal, and more silicone rubber. It doesn't stick well to other materials, like wood and some plastics. My preferred work surface is polyethylene plastic, because the silicone peels right off of it when it hardens. Plastic trash bags are polyethylene plastic and can be stretched out over a board or table as a work surface. I bought some thicker polyethylene years ago that didn't need stretching. Recently, I found thick polyethylene plastic kitchen cutting board, which I plan to use as a work surface in the future.
If you get it on your skin, wipe it off right away. It is not immediately aggressive, but skin contact for too long can cause your skin to peel.
Silicone rubber has very good longevity. As a sealer, it is guaranteed outdoors for 30 years. An indoors sculpture should easily last a lifetime.
Step 2: Palette Knives
The palette knives used by painters make very useful tools for spreading silicone rubber. They are like little plastering trowels. Some are made of plastic and some are metal. Some of the silicone material always seems to harden up on them, so you have to scrape them occasionally with a knife.
You can squirt the silicone directly from the cartridge onto the piece you are making and spread it around with a palette knife. You can also squirt clear silicone onto a disposable paper palette and use the palette knife to mix powdered pigments into it for color effects. Do it quickly, because the silicone hardens fast.
You can extend your working time for details by packing the silicone in a syringe with a palette knife and then extruding from the syringe. This is described in the next step. The palette knife is one of your most useful sculpture tools for silicone rubber.
Step 3: Syringes
In air, the silicone starts to harden quickly. To extend your working time for details, it is sometimes useful to colorize the silicone and pack it right away in another closed container, a syringe. Air won't get to the mass inside the syringe, and you can extrude what you need out the end. It's like a grease gun cartridge in miniature.
You can buy large syringes at pet shops or veterinary supply stores. With standard syringes that have metal needles, you can't use the needles they come with for detailed work, because the diameter of the hole is too small to push the silicone through it. You can make disposable plastic needles with larger holes out of some cotton ear swabs with plastic stems, or you can use the syringes without needles. See the next step for how to make the disposable needle tips.
Recently, I found these curved plastic needle syringes available at a pet store. They are used for feeding birds and baby animals. The conical tip can be cut at different locations for different size extrusions, eliminating the need to make special needle tips.
The rest of the syringe consists of a clear plastic barrel and the piston part with a rubber head. They can be cleaned and reused many times, but eventually they will become unusable and need replacement. I made some special cleaning tools out of wire to clean out the nozzle end barrel. A straight, or curved wire cleans the nozzle and one shaped like a miniature hoe snags silicone inside the barrel. The syringe barrel is polyethylene plastic, and the hardened silicone doesn't stick well to it. Pumping the plunger in it a couple times cleans much of it out. The plunger is cleaned just by wiping it, or peeling off any rubber build-up.
Step 4: Special Needle Tips
Q-Tip brand cotton swabs use fibrous material for their stems. They are probably top of the line for cleaning ears, but for making syringe tips they are useless.
Cheap cotton swabs use a piece of small diameter plastic tubing for the stem part. Years ago I used this material to make special needle tips for my syringes. I removed the cotton from the ends and ran some fine wire through the tubing. By carefully softening the plastic over a low propane torch flame and pulling the ends of the tubing in opposite directions, the center area elongated and reduced in diameter until it reached the wire inside.
After the stretched plastic cooled, I cut it with a sharp X-acto knife to make two needle tips. The reduced diameter part would fit through the hole in the end of a syringe, but the full-diameter part would jam in the hole. I used it as much as I could, and when it clogged I just discarded it and loaded another.
In order to do photos for this instructable, I tried to make make more disposable needle tips today and failed. The tubing wall is thinner than what I used before. These photos will give you the idea of how to make them, but the needle tips shown are bad examples of what they should be. You will have to find better quality cotton swabs to make your needles out of.
Step 5: Details With Syringe Extrusions
This is a fancy "taxi horn" like antique cars used to have. You squeeze the rubber bulb and the air makes a reed vibrate, making the honking sound. The colors are all silicone rubber with powdered pigments, not paint.
I made the bulb over a toy balloon. After the silicone hardened, I popped the balloon to remove it.
Step 6: Small Figurines
Most of these small figurines are solid silicone rubber, built up over silver soldered stainless steel welding rod armatures. Where wooden bases are used, holes were drilled and the armatures extend into the wood.
Perhaps, I have been too enamored by bronze sculpture. I seem to have done a lot of imitation bronzes out of silicone. Years ago I got a can of powdered bronze from a marine supply store. Mixing that in with silicone makes it look like bronze.
The bronze powder is made by an interesting process. There is something like an arc welder that has two rolls of wire, in this case bronze wire. The wire is fed to where they meet and an electric arc melts them. A compressed air jet in the liquefied area blows out a spray of micron size particles. You can "paint" things, like an apple for example, to build up metal molds. You can even spray paper and it won't burn, because each droplet of liquid metal contains so little heat. If you just spray the metal into a room, the droplets cool and fall as dust to the floor where the powder is collected.
Step 7: Styrofoam and Silicone
This abstract sculpture, "Mini-Monument", was about 3 ft. tall. I say "was" because it was not a strong material combination and it broke when someone bumped into it with a car. The sculpture was made of pieces of Styrofoam stuck together with silicone. A skin of bronze-colored silicone was then plastered over the Styrofoam.
When it bends, Styrofoam breaks easily, but if you laminate a non-stretching skin onto it, such as cloth, you prevent a crack from starting. If it can't start, it can't continue, and the piece won't break. Silicone rubber stretches, so it doesn't prevent the crack from starting. This is not a good technique, if strength is important.
Still I liked the sculpture, and could imagine it on a giant scale, that one could walk around in.
Step 8: Silicone and Cloth
These hanging fish are carved out of Styrofoam and laminated with cloth using clear acrylic medium (artist paint medium). The fins are made out of silicone rubber and cloth.
On a non-stick polyethylene surface I spread out the cloth and covered it with clear silicone, using a palette knife. After it hardened, I peeled it off, turned it over and did the other side. The silicone penetrates the cloth weave, so the cloth is mechanically locked in. After making sheets of the material, I cut out the fins with scissors and added the ribs with a syringe.
I used a similar technique, using fiberglass matting and silicone, to make a rubberized shower curtain. https://www.instructables.com/id/SHOWER-CURTAIN-Silicone-and-Glass-Fiber-Mat
Where the fins penetrate the cloth skin, cut the skin with a knife first. Using a soldering iron with a flattened blade, I melted slots in the Styrofoam bodies in which to set the fins with more silicone.
These fish are light-weight, really tough and hard to break because of the cloth skin.
Step 9: Hollow Silicone Sculptures
There are different ways to make hollow shapes out of silicone. These sculptures were first made out of water-base clay over PVC pipe armatures. The armature is still inside them. A layer of silicone rubber covered the clay. When the silicone hardened, it was cut with a knife and the clay inside was removed. The slits in the silicone were then patched with more silicone and the surface was colorized. Normal paints won't stick to silicone rubber, so you have to make your own "paints" out of clear silicone and powdered pigments.
You can make hollow shapes, like squeeze bulbs, over balloons. An alternative technique is to use Styrofoam as the core and then introduce a little solvent, like lacquer thinner into it to dissolve the Styrofoam, leaving the core hollow. Silicone rubber is impervious to even strong solvents like lacquer thinner, or acetone.
Step 10: Mattress Foam and Silicone
These big hanging fish sculptures are soft sculptures. If they fall, they won't get hurt, or hurt anybody. There is some flattened PVC material as an armature, which allows some side-to-side flexing like a real fish body, but not up-and-down flexing. Mattress foam was glued to both sides of that with silicone. It takes very sharp scissors to cut the foam, so I sharpened a pair up like two knife blades. It is fairly easy to sculpt inside the mouth, because the mouth flexes and can be opened up.
A skin of bronze-colored silicone was applied to the surface of the foam with a palette knife. The scales were added with clear silicone directly from the grease gun cartridge.
I like the idea of hanging fish. It is as though they were swimming in water.
Step 11: Using Molds
I never found a way to get a smooth surface on sculptures directly, so I used plaster molds to imitate smooth cast bronze surfaces The original sculptures were made of clay.
The silicone needs to lose acetic acid to harden up, and it can't do that in a closed mold. Also, large masses of silicone take forever to harden up completely because the acetic acid has to find its way out from the core.
I made these sculptures using open molds. The plaster molds were first dried, coated with shellac, and then with a coating of a mold release agent such as wax. When that was dry, I "painted" the inside of the mold with bronze colored silicone and then filled the rest of the cavity with a "bird nest" of clear extrusions directly from the grease gun cartridge. Since the tangle of extrusions had air passages running through it, the core could ventilate and the whole thing could harden up in a reasonable amount of time.
The "Frustrated Artist" pulling his hair was made in an open mold. I coated the back side with a layer of silicone later to seal the air cavities.
The "Belly Dancer" was a much more complicated piece. All together, it is 40 inches tall. The base cylinder is hollow, a piece of PVC sewer pipe, and the three figures on it were each made separately in open face molds and then adhered to the pipe.
The top figure, a sculpture in the round, was made in two halves that were then carefully joined. She has a section of flexible vinyl tubing going up the center of her, and a piece of 1/4 inch rebar inside the vinyl sleeve to give rigidity, since she herself is quite flexible. The idea is to someday put a slow motor in the base connected to the rebar shaft. With a bend in the shaft, she should do a nice hip motion belly dance. The idea was inspired by a little rubber hoochy-coochy dancer toy I once saw that danced when you turned the crank. Maybe I'll get around to finishing it someday.
Question 4 years ago
Does anyone know what type of silicone he used
Answer 4 years ago
I'm no expert on the different types of silicone. I used what I could get in local hardware stores for sealing windows, etc.
Reply 4 years ago
12 years ago on Introduction
That's all very interesting, I'd like to see more of your "bronze powder" technique.. I've read that two part Silicone comes in two varieties, "Tin Cure" and "Platinum Cure" and the only ONE of these is sufficiently non-toxic to be "food safe". Where does this kind of Silicone fit and could you use it for things that would come into contact with food?
Reply 5 years ago
I know this question is seven years old and probably everyone knows the answer now, but just for the record; Platinum cure silicone rubber is food safe, tin cured rubber is not.
Which brings up another point-- not all pigments are non-toxic, so if you happen to be experimenting with artist's powdered pigments take time to read the MSDS and make sure it's suitable for your use. Even though the pigment should be encapsulated within the rubber.. who wants to have to defend themselves from the lawsuits...
Reply 12 years ago on Introduction
I used a self-made silicone rubber non-stick sheet years ago to bake bread on in my microwave oven. I never got sick from it. Other than that, I am no expert on the subject of silicone and food safety. It lasts at least 30 years outdoors, so it must not be discharging much material, if any under those weather conditions. It doesn't dissolve in acetone or lacquer thinner, or water for that matter, so I doubt it would dissolve in saliva. Anyway, I doubt it is a great health risk.
I'm not familiar with the two part varieties. I know something similar is used for making flexible molds.
6 years ago
i need to remove that sticky surface of silicon how can i do that and thq
Reply 6 years ago
Hi Mina, Silicone sticks like crazy to some things and not so well to others. You mention the "sticky" surface, which tells me you are talking about fresh silicone, and you may be referring to silicone on the hands. Just wiping the best you can with a napkin, or rag is probably the best way. A thin film stays, but eventually wears off. On glass or metal, if it hardens up, you have to cut it off with a knife.
Don't get it on your hands to begin with, if you can. Use tools, like a palette knife for working with it.
Reply 6 years ago
thq , i love ur work and ur way in giving info wz all details greating from egypt
Reply 6 years ago
6 years ago
I would like to cover cloth with Silicone caulk to make rivers and roads for wargame terrain.
How much working time do I get? I would like to make pieces up to six inches by 12 inches and about 1/16 thick.
How can I get a blue or green tint in the caulk? Can I color chalk with tempera and then make powder of the chalk? Should I use acrylic paint?
Great piece, Great 'ible
Reply 6 years ago
I think a product called "Magic Water" would work better for what you want to do. It is used by railroad diorama makers and game players. If you google online, you can find a lot of instructions in various forums on how to make realistic looking water, streams with ripples, etc. There are alternate products for doing the same, but magic water has the best user reports online. I did a lot of research on it in the last few months. Buy at hobby stores, Amazon, eBay.
Reply 6 years ago
Try it to get a feel for how much working time you get.
I color clear silicone with powdered pigments. Cheap powdered colors for cement can be found in some hardware stores. More expensive colors come from art supply stores. Mix them with the silicone on a palette with a palette knife. No paints stick well to silicone rubber. If you want to paint it you have to use clear silicone and a pigment.
6 years ago
مشروع فكرته رائعة خصوصا في استعمال الحقنة لتغطية الشيء المراد قولبته.
Reply 6 years ago
Is there a translator in the house? Good luck exploring the material. Have fun.
Reply 6 years ago
Here you go Thinkenstein! Hope is not too late though ;o)
مشروع فكرته رائعة خصوصا في استعمال الحقنة لتغطية الشيء المراد قولبته....
Project fantastic idea , especially in the use of the syringe to cover the thing you want to mold it.
Reply 6 years ago
Thanks HaydeeJ. Very nice of you to translate this for me.
7 years ago
Hello guys, I just bought a statue with silicone head and hands. My question is, how do I clean it and maintain it so it will last long? I am keeping it in an air conditioned room because I am in the Philippines, and the climate here is hot and humid. Thank you.
Reply 7 years ago
As far as the silicone I use goes. any biofilm can usually be cleaned off with Chlorox (chlorine bleach). Hot and humid doesn't seem to bother the silicone, itself.
Reply 7 years ago
Thank you for this, my friend. I was told by different people on the net to:
1. Use baby wipes w/o alcohol, 2. Brush with thin layer of baby powder every six months.
3. Use adhesive tape to remove dust and other dirt/ particles.
Are any of these okay to do? How ofter should I do them?