Introduction: How to Make Your Own Sugru Substitute
I call it Oogoo, an inexpensive silicone clay that is easily made. It can be used as an excellent substitute for Sugru. It can be hand molded or cast in forms. Or, it can be used as a casting silicone. It can be colored any color from white to black. It can also be made translucent to allow diffused light to shine through. It can even be painted on in thin layers. It has very good adhesive qualities and will stick to itself, glass, fabric, paper, wood, and some plastics and metals.
This instructable will show :
1- How to mix and color Oogoo
2- How to cast it or hand form it into different shapes.
3- How to make silicone paint
4- Several interesting uses for Gorilla tape and Gorilla Glue, see steps 3, 7, 12 and 15.
5- How to make a few projects using Sugru and a comparison of Oogoo and Sugru
Since I am mainly interested in using Oogoo to embed electronic circuits in flexible forms, this instructable will also show you how to:
1- Make a soft circuit LED pumpkin head robot display that can be embedded on to clothing.
2- Make cleanly etched conductive fabric circuits
3- Make conductive glue using Gorilla glue.
4- Embed circuits in Oogoo or Sugru
The intro pic shows a few of the silicone shapes that I made using Oogoo and a funky, smirky, flexible pumpkin head robot LED display.
Step 1: How It Works
pic2 shows a 2"x2"x2" solid silicone cube that cured enough in two hours to be removed from its plastic box form.
For years I have been looking for an inexpensive way to create a flexible skin covering for robots and electronic circuits. I have tried several kinds of casting urethane rubber and silicone rubber. They all have their difficulties and either set up to fast or too slow. They are too thin or they are too thick. They are also very expensive in small quantities. Added to that is the problem that they have a very limited shelf life and usually must be used within six months. Sugru is great, but it is not affordable for making larger structures.
I and many others have tried using the inexpensive silicone caulk that is readily available from hardware stores. It is used to seal roofing and glass windows. It works fine but has the problem that it can only be used by putting it on thinly and waiting a long time for it to cure. It is also hard to work. It must be smoothed immediately while it is very sticky. Otherwise, the surface cures quickly and then forms a gummy film while the inside remains soft and wet. It has a smoothing time of seconds rather than minutes. If you put it on too thick the inside will remain soft and can take several days to finally cure. People have tried all kinds of additives in an attempt to make it cure in a more useful manner. I have found those additives to be unusable for my purposes.
So I wanted to add a catalyst that would help the silicone to cure from the inside out rather than just from the outside in.
As I understand it, 100% silicone caulk works by the moisture in the air initiating the polymerization of the silicone. So it cures from the outside in and as it does, it allows the water vapor to slowly seep inside and eventually cure the unexposed silicone. While it cures, it gives off Acetic acid (vinegar is diluted acetic acid) which is the strong smell you will notice if you use it.
I experimented with quite a few additives to try and introduce some moisture into the uncured silicone. Several of them worked to some degree, but the hands down favorite was also the least expensive.
It turns out that corn starch is highly absorbent and when sitting around in an open box it will absorb moisture from the air. It is an extremely fine powder that diffuses evenly in mixtures. By adding the right amount of corn starch, the sticky silicone is somewhat stiffened and very quickly starts to set up from the inside out. While it still sets up faster on the surface than in the middle, the whole thing will set up in five minutes to 2 hours no matter what the thickness. The actual curing time depends on the temperature, the humidity, the amount of corn starch added, and the speed at which it was mixed.
So that's it. Oogoo is corn starch and clear silicone caulk mixed together and then molded by hand or by forms to create just about anything you can imagine that needs to be adhesive initially and solid yet flexible when cured.
Step 2: Materials
Materials to Make Oogoo:
100% clear silicone caulk-the kind that gives off the vinegar smell while it cures. Can be found in any hardware store or Walmart. It cost from $3 to $5 for a 10 oz. tube. The newer silicone caulks that have a different smell such as GE silicone II will not work for this.
Caulking gun for silicone tubes.
Gorilla instant glue
100% Corn Starch
Linseed based oil paints to color oogoo
Materials to embed an etched circuit:
Clear Contact vinyl shelf liner from Walmart or hardware store.
Ferric Chloride etchant
Gorilla white glue
Surface mount LEDs
Magnet wire or conductive thread
Veil shield conductive cloth from http://www.lessemf.com/
Step 3: Mixing Oogoo
Mix By Volume
As stated before, Oogoo is simply a mixture of clear silicone caulk and corn starch. It can be mixed anywhere from 5 to 1 to 1 to 2 silicone to corn starch by volume. Up to a point, the more corn starch you add the faster it will set up. I like to mix it in small disposable cups using a Popsicle stick that is wrapped with Gorilla Tape to create a spatula. See pic4. Once it cures the Oogoo peels easily off the tape wrapped stick and the mixing/spreading stick can be reused.
Mix In Small Amounts
A good starting mixture to try out is 1 corn starch to 1 silicone by volume. It is easiest to mix it in small quantities so as to have plenty of time to work it. To see how it works, you could start with 1 tablespoon silicone caulk to 1 tablespoon of corn starch. You can reduce the amount to as little as 1/4 tablespoon corn starch to 1 tablespoon silicone if you want more time to cast it or sculpt it. I rarely mix up more than 3 tablespoons of silicone at a time.
The dry starch and sticky silicone do not want to easily mix. But if you are persistent and keep quickly stirring and mashing the mix, they will eventually merge into a thick paste. The resulting Oogoo is very sticky and will stick to anything that you spread it on. Most things it will stay well glued to. On a few things like some plastics and metals, it will easily peel off after it has cured.
The resulting Oogoo is a nice reflective white but I recommend coloring it so that you can easily see if you have an even mix. See the coloring step.
WARNING: While mixing, Oogoo will give off the strong smell of Acetic acid which can be irritating to the eyes and respiratory system. I strongly recommend that the mixing and forming be done outside or in a VERY WELL VENTILATED room. You should also wear nitrile gloves while mixing as the uncured silicone contains other solvents that might be absorbed by the skin.
One recurrent problem with silicone caulk is that once opened, it will tend to set up in the tube tip. To get a good seal I have had good luck using Gorilla tape wrapped over the tip. See pic4b. If you leave a quarter inch gap between the wrapped tape and the tip you can squeeze out just enough silicone to seal the tip well from air and moisture.
Step 4: Hand Molding
Pic5 shows the fresh mix mounded up to create a glass stopper. Pic6 shows the final hand molded form.
Oogoo can be hand molded onto or around just about anything. However, you will have to move fast as the fast mix will fairly quickly go from sticky to putty to a clay like material in just a few minutes.
Mix up some Oogoo as quickly as you can and then use the mixing stick as a spatula to spread the Oogoo on whatever you want it to stick to. While it is sticky mound it up to a shape that is roughly what you want the final shape to be. Let it set up until it is barely sticky and then start patting it into the form you want. At some point it will be like clay and can be fine tuned to its final shape.
A mix of 1 corn starch to 1 silicone caulk will be like a putty in 1 to 2 minutes and can then be hand smoothed. In 3 or 4 minutes it will be like clay and can still be molded but is hard to smooth. So, you only have about 5 to ten minutes of working time with this mix.
A mix of 1 to 3 or 4 will give you up to thirty minutes working time. A 1 to 5 mix can give you an hour or more working time. Depending on how fast it is mixed, the thickness of the structure, the temperature and the humidity, the slower mixes will turn solid and rubbery in from 5 minutes to an hour.
If while mounding your shape, you run out of Oogoo, don't worry as you can just mix up another batch and add to it while it is curing. A fresh mix will stick really well to Oogoo that is curing or even Oogoo that has cured for several days.
Step 5: Coloring Oogoo
I was pleasantly surprised to discover that all it takes to create vibrant colors in Oogoo is very small amounts of linseed based oil paints. Apparently the pigments in oil paints are very fine and dense so a little goes a long way.
About the equivalent of 5 or 6 drops of oil paint per teaspoon of silicone will result in solid colors. I mix the color well with the silicone before adding the corn starch.
While you can leave it white, it is a good idea to add some color to make it easy to see if you have a well mixed batch. Adding color does not appear to significantly effect the hardness or flexibility of the final result.
Step 6: Sanding and Carving Oogoo
While you can cut Oogoo with a knife, its rubbery flexibility makes it difficult to get precise cuts. It is more easily carved or sanded with power tools.
I used a stationary disk sander with 150 grit sandpaper to sand smooth the hand formed stopper in pic8. It sands cleanly but It is slow to sand, so before it cures, you should try to hand form the structure as close as possible to the final desired size. I made the mistake of not putting a mold release such as Vaseline on the glass vial and it was very difficult to remove the stopper after it cured.
Oogoo can also be carved with a Dremel tool and a high speed carbide wheel. Wait at least twenty four hours before carving smaller objects and up to several days for thicker ones. Do not carve until the strong smell of acetic acid is mostly gone when you put it up to your nose. Otherwise you will be shooting very small particles containing irritating acid into the air. Not Healthy. Do this outside with a filter mask or with a good vacuum system.
Step 7: Casting Oogoo
Casting In Plastic Containers
Just after mixing, Oogoo is very adhesive and will stick to almost anything. It will not remain stuck to some plastics such as PVC, polyethylene and polycarbonate. So any kind of container made out of these plastics can be used as a form or mold. The blister packs used to package many products contains clean smooth forms that can be used as casting forms. Clear polycarbonate cups and dishes can also be used.
Pic9 shows a funnel shape that was made using the inside of a polycarbonate martini glass. The Oogoo ended up about 3/16" thick and is quite flexible. It could be used as a funnel.
Simply smooth on the mix to fill up the form in layers while working out the bubbles. It does not have to be done in one mix. A fresh mix will stick very well to oogoo that is setting up and also to older Oogoo that has fully cured. So layers can be added at any time.
Casting in Gorilla Tape
Oogoo does not stick to Gorilla Tape so the inside or outside of any container or surface covered with the tape can be used as a form. After it cures the Oogoo will peal easily off.
Step 8: Making Tubes, Sheets and Laminations
It is easy to make sheets of Oogoo. Simply spread out a mix between two layers of clear polyethylene and then roll it with a round object as if you were working dough. See pic10. I like to use polyethylene plastic from gallon freezer bags. If you put down spacers of thin wood or metal you can keep the thickness uniform.
Once flattened, If you just want a single sheet, then wait 4 or 5 minutes and then peel off the top layer of plastic. This will leave a very smooth surface top and bottom.
If you want to work it more, then peel off the top plastic after 2 or 3 minutes while it is still a bit sticky and then form around whatever you want it permanently attached to.
To make layers, make one layer and let it set up until it is fairly stiff and then roll out another layer nearby. When it is set up enough pull of one layer of plastic you can then stick it on top of the first layer. You could embed whatever you want between the two layers such as a tool blade or a printed circuit board. Pic11 shows a three layer lamination.
Tubes are a bit more tricky and require fast working. Use a plastic tube or wrap Gorilla tape around a dowel to create a form that the Oogoo won't stick to. Make a sheet of Oogoo that is wider than the diameter of the form. As soon as you can, peel the top layer of plastic and wrap the sheet around the form. Make sure there is overlap where the edges meet and quickly smooth out the seam.
Step 9: Make It Glow
Oogoo has many possibilities for lighting fixtures or light ribbons. Pic12 shows a 4" translucent cube that was made by coating an acrylic cube that I had with a thin layer (about 3/16") of translucent Oogoo. It was then lit up using a 1 watt white LED.
The Oogoo can be made translucent by using a 1 corn starch to 3 or 4 clear silicone caulk mix.
Step 10: Making Silicone Paint
Pic13 shows the final robot pumpkin head with LEDs all on. I used it to experiment with different mixes of silicone paint.
This is not a new idea, but silicone paint is easily made. Simply add naphtha or mineral spirits (paint thinner) and oil paint to the silicone caulk until you get the consistency of paint you want. The only problem with the paint is that it dries much weaker than silicone caulk alone or Oogoo. It has lower adhesion and lower tear strength. Even so, it is useful for some things.
I like a 1 corn starch to 3 mineral spirits (or Naphtha) to 3 silicone caulk for a translucent white gel-like paint. For a paint that is thinner and closer to an oil paint thickness you can use a 1 cornstarch to 4 mineral spirits to 2 silicone caulk. The more solvent you add, the weaker the final strength and adhesion will be.
You can also use acetone, xylene, or toluene but they all have nasty fumes and take several days to dissipate in thicker applications. The Naphtha has the advantage that it evaporates fast and loses most of its smell overnight.
Solvents that give off less noxious fumes and can be used to thin Oogoo and Oogoo II are turpentine and Citrus Solvent. Their only problem is that they can take several days to evaporate in a thicker cast of silicone rubber. For paint thicknesses they work fine but set up pretty slow.
Step 11: Etching Conductive Cloth for Soft Circuits
Pic14 shows a ribbon cable made of etched conductive cloth (Veilsheild). LEDs could be glued on it to make a light ribbon. Clean and sharp conductive traces like this are possible using the method described below.
For the robot pumpkin head circuit I wanted to etch a very simple pattern as I was going to be trying several new techniques to glue and laminate the circuit.
The problem has always been to find an inexpensive, simple way to get a resist that is removable but will etch sharp high resolution conductive traces. I experimented with all kinds of tapes but they were either not waterproof enough or they had so much adhesion they peeled off the conductive coating on the fabric.
I finally tried clear vinyl shelf liner. It is just sticky enough to keep out the ferric chloride etchant, but not so sticky that it wont come off cleanly. the conductive cloth is placed on a piece of shelf liner with its sticky side up. this seals the back side. Another piece of liner is cut with a sharp x-acto knife to remove vinyl wherever the circuit needs to be etched. The conductive cloth is then sandwiched between the two layers of shelf liner. See pic15.
The cut traces are then burnished with a Popsicle stick to make sure the edges are adhered well to the cloth. It is then dipped into ferric chloride etchant for five minutes at room temperature. As soon as it looks well etched, it is removed and immediately submerged in a bucket of water and swished around. Remove it from the water and then rinse it some more to be sure all the etchant in the fibers is removed. the shelf liner can then be slowly peeled off and the cloth left to dry. Pic16 is the final cloth circuit board.
I have been experimenting with etching conductive cloth for several years. For some of the results see here: https://www.instructables.com/id/Conductive-Fabric-Make-Flexible-Circuits-Using-An/
Step 12: Glue the Circuit and Laminate It
Making Conductive Glue Using Gorilla Wood Glue
To make a flexible pumpkin head Led circuit, a way to glue the components to the cloth circuit board is needed. Gorilla Wood Glue can be easily made conductive and still have good adhesive qualities.
Mix by volume: 3 powdered graphite to 2 Gorilla white glue. The powder is reluctant to mix but keep at it till you have a sticky paste. You can then blob it onto the wires you are gluing to the conductive fabric traces. While you can add a few drops of water to make it easier to work, this will increase somewhat the final resistance of the conductive joint. Let it dry overnight.
This conductive glue has a very low resistance and is good for connecting two conductors that are close to each other. You can obtain powdered graphite from: http://www.elementalscientific.net/
Pic17 shows how the glue joints looked after the led wires were glued to the conductive circuit board. Because the PLCC2 surface mount LEDs do not have enough surface area to directly glue them with conductive glue, I first soldered thin tinned lead wires to them. This gave more surface area to the glued conductive joint. I zigzagged the leads thinking that might increase the flexibility of the final result.
Gorilla Tape Helping Hands Jig
See pic18b for a helping hands jig I used to hold the surface mount LEDs and thin wire while soldering. It is made of Gorilla Tape taped sticky side up on a piece of cardboard. I had previously used blue tac for this, but this works just as well.
Laminating the Pumpkin Head
Pic18 shows the pumpkin head after laminating with orange Oogoo. The Oogoo was cut off to expose the LEDs. Translucent and colored Silicone paint was then used to finish the pumpkin head.
I have been experimenting with conductive glues for a few years. For other ways to make and use conductive glues see here: https://www.instructables.com/id/Make-Conductive-Glue-and-Glue-a-Circuit/
Step 13: The Robot Pumpkin Head Circuit
The LEDs are flashed in sequences using a 08m Picaxe microcontroller. See pic19. The resistance of the conductive glue joints is high enough that no dropping resistors are necessary. In order to keep the leads to a minimum, Charliplexing is used to control the six LEDs individually. This is a simple way to use 3 wires to control 6 LEDs.
I will try an post a video of the flashing pumpkin head LEDs and code when I get more time.
For details on Charliplexing see: https://www.instructables.com/id/Charlieplexing-LEDs--The-theory/
I did not have time to make an embedded control circuit, so it was just breadboarded. See pic20.
Step 14: Comparison of Oogoo and Sugru
Pic21 shows a eyeglass holder made with sugru on one side and Oogoo on the other to hold on the neoprene neck strap.
Pic22 shows a small coin cell flashlight I made on a circuit board and then covered with Sugru.
Pic 23 shows a Picaxe circuit I laminated on the bottom side with Sugru to protect the thin wires on the back and keep it from shorting.
I experimented around with several packets of Sugru to see what it would stick to and to see what it took to mold it to clean shapes.
Advantages of Oogoo:
1- Made from inexpensive and easily obtained materials.
2- Easy to work and mold into forms.
3- Will set up quickly at any thickness.
4- Can be mixed in any color.
5- translucent structures possible for lighting aplications.
6- slightly more flexible than Sugru.
Advantages of Sugru:
1- Much milder fumes, can be easily used indoors.
2- Cures to a harder rubber.
3- Gives more working time.
4- Already mixed.
5- Somewhat easier to smooth.
6- Carves easier than Oogoo.
Step 15: Other Possibilities
Pic24 shows the LED robot pumpkin head mounted on a T-shirt. It can be glued with silicone caulk onto most fabrics and should be able to handle hand washing.
Pic26 shows the flexibility of the final circuit.
Make Conductive Rubber And Robot Skin
See here: https://www.instructables.com/id/Conductive-Rubber-Make-Touch-Sensitive-Robot-Skin/
Make Conductive Rubber And A Transparent Capacitive Stylus For Ipod, Iphone, And Ipad
See here: https://www.instructables.com/id/Make-Conductive-Rubber-Transparent-stylus-iPodiP/
Making Ooglo: Luminescent Silicone Paint
See here: https://www.instructables.com/id/Making-Ooglo-Luminescent-Silicone-Paint/
All manner of masks and appendages can be made using Oogoo. It sticks well to cardboard and paper and almost anything. You can use it to glue almost any part of the costume together and it sets up faster than most glues. Be sure not to create anything where you will have to breathe near freshly formed Oogoo. Let it sit a day or two and use it only after the vinegar smell is gone.
Make Your Own Lego Parts or Interlocking Blocks
All kinds of interlocking building blocks or circuit modules could be built.
Electronic cases of different kinds can be quickly hand made with Oogoo. It might even work as a forming material for a 3d printer or rapid prototype machine.
Colored Oogoo sticks very well to glass and can be used for various stained glass effects.
It should be possible to make hinges using thin flat sheets of Oogoo glued to wood boxes or cabinets. It may also be possible to use it to make flexible joints for furniture.
Metals that melt at low temperatures can be cast in Oogoo. See pic25 for a ring I cast out of bismuth.
Gluing to Plastics
Near the end of this, I discovered that Oogoo can be glued to many plastics using Gorilla Super Glue. If after it cures it peals off the plastic, try re-gluing it using a thin layer of super glue.
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Can you use RTV silicone?
Will this work with caulk that is a mixture of latex and silicone? It's much cheaper 100% silicone caulk for large projects.