Homemade Silicone O-rings and Tubing


Introduction: Homemade Silicone O-rings and Tubing

Make your own O-rings and tubing from silicone!
The object in this picture is a homemade submersible camera housing, made possible by the silicone O-rings.  (my next instructable will be the camera housing)

Quick and dirty explanation: Inject silicone adhesive straight from the tube with a caulking gun into clear Vinyl tubing, let it cure, blow the silicone out with compressed air, cut the silicone to length, re-glue it to form rings. If you want tubing, blow out the silicone before it cures...
This instructable will not only show how to make the O-rings and tubing, but go into detail about the way silicone adhesive behaves so you can exploit it, and make even more things!

Step 1: Materials

The primary material is Silicone adhesive that comes in tubes for caulking guns.

1. THERE IS A DIFFERENCE AMONG SILICONE TYPES. DO NOT USE "Silicone II", it is not pure Silicone, and will not behave as predictably as "Silicone I" , (or 100% silicone). The black Silicone is from ACE and is my favorite. Clear GE Silicone 1 is great too.

2. Clear Vinyl tubing. This is what you will be pumping the silicone into, it's the mold for the O-ring and tubing. The "I.D." or inside diameter of the tubing will be the "O.D." of the Silicone O-ring you are making.

3. Masking tape, compressed air, sharp knife, high quality caulking gun, about a week of cure time.

Step 2: Inject the Silicone Into the Vinyl Tubing

Using the caulking gun to force the Silicone into the Vinyl tubing, squeeze away! You will notice that as the Vinyl tubing fills up with silicone, it will get harder and harder to fill, due to the high viscosity of the Silicone. It will take considerable pressure to hold the Vinyl tubing onto the tip of the caulking tube. (a nice caulking gun is worth the price here)
You may only be able to pump about 15 or so inches of silicone into the Vinyl before it just wont take anymore, and you will actually feel the Vinyl tubing expand from the pressure!

The tubing shown here has an I.D. of 1/4 inch, which is an amazingly convenient size. The only other size of tubing I've tried is 1/8 inch I.D., anything bigger than 1/4 inch I.D. will take some special care... but more about that in a minute.

Step 3: Optional : Make Hollow Tubing Instead of Solid Silicone

At this point the Vinyl tubing is filled with uncured Silicone, and you can keep it solid, or make tubing out of the silicone itself!
All that needs to be done is apply compressed air back into the Vinyl tubing, which will force the uncured Silicone to flow back out, while leaving enough of it stuck to the inside of the Vinyl, so that when it cures, it will be tubing!

If you use compressed air to do this, use the bare minimum amount of pressure. The reason is, after the silicone is forced out, the sudden blast of compressed air through the tubing will cause the thin film of uncured silicone stuck to the inside of the Vinyl to "Ripple" due to violent turbulence of the compressed air

Step 4: Waiting for the Silicone to Cure

Now comes the waiting... a little extra information while we wait for the cure:
The interesting thing about this method, is that the Vinyl tubing material, though waterproof and highly resilient, will not prevent the Silicone within from curing. The Vinyl does not make a good "vapor barrier" and therefore permits curing. Silicone cures from the outside in.
The (solid) Silicone if left in the 1/4" Vinyl tubing may take more than a week to cure. If anyone has ideas on how to speed up the cure< let me know.

The silicone that has been blown through to make hollow tubing, will take a single overnight, maybe more.
The difference is that the air can get to the inside of the tubing and help it cure faster.

Being the impatient person that I am, waiting is hard. The first few times I made these, I kept checking and checking. The Silicone that is near the ends of the Vinyl tubing will cure relatively quickly, even up to a half an inch of it will quickly cure due to its proximity to open air. Do not be fooled, the Silicone deep inside the Vinyl has a way to go yet.

You may want to make a few lengths of this tubing at once, if for no other reason that to test how the cure is coming along. Just cut a section of your test tubing, any others should be about the same.

If anyone uses Vinyl of more than 1/4 inch I.D.  Let me know how it goes!!! (my prediction is a ridiculously long cure time...)

Step 5: De-molding the Silicone From the Vynil

Now comes the really really fun part! - Removing the cured Silicone from the Vinyl tubing!
There are two methods for doing this. The compressed air method works only on solid Silicone. It's as simple as it looks: Hook compressed air up to the Vinyl tubing and blow!
This method at first seems like it wouldn't work, after all, you cant push on a rope right? But what happens, is that the compressed air will cause the Vinyl to expand, and therefore separate from the cured Silicone within, leaving a slight gap... the compressed air will work it's way down the gap between the Silicone and the Vinyl, and create turbulence between them.

The sound of this happening is hard to describe, but sounds like pinching a latex balloon opening so that it squeaks loudly. The Silicone will shimmy its way out of the Vinyl without you having to do much except laugh at the simplicity of it all.
(This joy is similar to the joy experienced by the Flying Spaghetti Monster as it gives birth to spaghetti children... or so goes the legend anyway)

If your Silicone is still uncured, this whole thing will not work.

The second method of Silicone removal is to simply pull it out of the Vinyl by hand. Since the Silicone shrinks when you pull a piece of it length-wise, it will pull away from the inside wall of the Vinyl tubing, and come out. You will probably find other ways of doing this, i.e. with water, etc. If you use the "pull method" it helps to straighten out the Vinyl tubing.

Step 6: Cutting the O-rings to Size

From the Silicone that has emerged from the Vinyl, you now have material for your O-rings!

1.Cut the Silicone rubber "cord" to the desired size (circumference)
2. Make the cut ends as flat and uniform as possible.

The silicone "cord" is VERY flexible and soft: pre-stretching it (by making the O-ring slightly small) is very usefull here, if your O-ring is meant to hold snugly around something. The Silicone should stay soft and pliable for a looooong time, many years.

Step 7: Join the Ends to Make the Final O-ring

Basically, you're going to use the same Silicone adhesive that you made the O-rings with, to glue the ends together.

1. Using masking tape, wrap both ends of the cord. Doing this prevents the Silicone you use for the fusion, from getting onto the smooth surface of the O-ring.

2. Using a wider piece of tape as a cradle, position one end of the O-ring.

3. Glob some Silicone onto the other end of the cord

4. Push the ends together, then lock the tape down. There is actually just a tiny amount of silicone used to fuse the ends together!

5. Keep the taped ends Parallel to each other, the O-ring will be "round" don't worry!

6. Wait overnight for cure

Step 8: Remove Tape, You're Done!

Remove the tape, and clean up the extra silicone from the joint, which should be very easy, since the tape prevented the silicone at the joint from sticking to the O-ring. The joint will leave a little imperfection in the O-ring, but the Silicone is so pliable, it will not affect sealing performance.

Enjoy, and good luck!

(My next instructible will be how to make the submersible camera housing!)



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    72 Discussions

    You have made my day! I was looking for a tube of a certain size and shape - now I can make my own, thank you.

    One more detail: The FSM gives birth to spaghetti? Is his almighty Noodleness a female? Who's yer daddy? Many, many years ago I saw a documentary showing the Spaghetti harvest in Italy. Oh - I found it on YouTube, it was made in 1957 (which shows how old I am).

    ugh sorry for the repeat postings, dont know why my computer isnt saving my text, showed up as nothing written when i reloaded page then typed everything again.. ugh


    Love this ! ima gonna try !

    For curing times, lightning fast, within reason & without compromising too much elasticity of the silicone properties, using cornstarch (yeap sounds crazy, but it works lol)

    Full credit to this chap;


    ive personally made molds like this for years, works surprisingly well - will try o-rings next and compare them to o-ring-cord, only comes in nitrile or neoprene that i could find on ebay..

    But to keep working time slower (more time to handle) id propose a mix of;

    0.5 to 1 part cornstarch

    2 parts silicone

    0.5 to 1 part mineral spirits

    Some experimentation needed here but this will drastically reduce cure time by HALF or even a day or two - for the hollow o-rings,, pfft, maybe less than an hour lol

    As mixing this slowly without adding bubbles will be an issue unless you happen to own a degassing setup, i'd suggest pouring this mixed sealant into a sandwich-bag corner, then cut a tiny part of the corner off the bag so this sealant can be piped (this is how cookery chefs pipe desert fillings/icing etc) into say, a LARGE Syringe,, this syringe could then be used to pump this mixture into the Vinyl tubes from a caulking gun, gently lol

    Or if you can find empty silicone caulk cartridges in your area, like this;


    Then that would be even better, hopefully reusable :)

    maybe even putting the mixed sealant into a sandwich bag corner, cutting a small hole in the corner of bag,, then piping the mixed sealant into a very large syringe then attaching this syringe to the caulking gun to pump it into the Vinyl tubing, will take some practise but i reckon this would be a good option :)

    howdy !

    Great instructable !!!

    A way of making the silicone cure ligthning-Fast, maybe an hour to a few hours instead of a week, is by mixing the silicone with cornstarch (i know, sounds crazy,, lol) and mineral spirits

    This highly reduces the working time but also the cure time, experiment with different concentrations of cornstarch to silicone as we are more interested in the o-ring functionality, maybe;

    2 parts silicone

    1 part cornstarch

    0.5 to 1 part mineral spirit

    Ive personally made molds using these ingredients and the work time is VERY Quick before it starts to set, depending on how much cornstarch you use,, if by only using a little, less that what ive shown as the example, then this will drastically reduce the cure time to a few short hours or only a day or two

    im definitely going to try this, piping the mixed silicone will be a bit of a challenge if one isnt quick but not too quick mixing or itll introduce too many air bubbles that will require an expensive degassing setup to completely remove all air bubbles from the mix.

    Full credit goes to this instructable among other authors who use cornstarch to make molds with silicone sealant on this awesome website:



    12 months ago

    Nice work

    Will have to try this and with the heat proof silicone can fix oven door.

    I read all the comments as well and there are some more good ideas

    there to.

    Did you do know that air set silicone dose not set because of the air .

    I sets because of the moisture in the air . It absorbs the moisture.

    Have you ever tried to stick silicone to a wet surface it just doesn't work.

    So I would try 'a' fill tube with silicone and drop it in a bucket of water or 'b' soak the tube in water first then fill with silicone and drop it in a bucket of water.

    I used a spray bottle of water to set silicone after filling gaps. This helps a lot.

    A skin forms all most instantly. Acrilic paint is mostly water.

    Hope this helps. Thanks for shearing. JIM


    1 year ago

    If I were interested in creating a silicon tube with multiple lumen, would you have any idea how to go about that?

    1 reply

    Hello! I'm not sure what you mean by multiple lumen?

    Yup! Just checked the tube of "GE 100% black all purpose silicone " This time I wore my glasses! Lol! In small writing it said "Silicone II". Thanks for your response. I'll try again with the right stuff.Thanks!

    Tried blowing out of the 1/4" tube after a week. No dice! Cut the tube open and the silicone was stuck to the tube pretty good. Any suggestions?

    1 reply

    Just shooting from the hip, sounds like the silicone wasn't cured all the way, or the silicone wasn't the 100% silicone type. I've seen silicone that is labelled 100% silicone, but its actually the substandard type II. The type II just wont work with this method.

    Also, was the tubing clear Vinyl? The downside to my method is the long cure time. I almost always make the hollow tubing now because the cure is much faster. The hollow tubing, once cured, can be filled with more silicone (while still in the vinyl tubing for support) to speed up the hollow tubing cure even more, I will let the air compressor bleed air very slowly through the tubing. An aquarium air pump might be perfect for this, it puts fresh air through all that uncured silicone and pushes out the stinky acetic acid vapors. Once the hollow tubing cures, say overnight, the silicone you pump through it will cure pretty fast,a day or two tops, my thought is that the cured silicone helps cure the uncured silicone.

    Best of luck, hope this helps you!

    This is pretty awesome. I totally stumbled on this page because I thought it sold silicone wedding rings like ImperialRings.com but hey, I'll be implementing this!

    this is simply brilliant!

    This is the best method for making o rings

    Hunh...I never thought about doing this before! I would probably use the same PVC tube, slice it lengthwise and use it as a splint to hold the silicone together while it cures. GREAT idea you have there!

    Great instructable. I can't believe it hasn't been featured. Thanks for all the advice folks!

    Hello everybody! Just an update... Recently I tried using a high temp red rtv silicone sold at most auto parts stores. Made some tubing that is much better than the silicone adhesive I was using before. Its oil resistant and heat resistant. It can withstand molten lead (smokes a little but it goes away) Motor oil and brake fluid didn't hurt it at all. Its far superior to the simple adhesive silicone which failed under high heat and most petroleum. It cost about 12 dollars for a regular caulking gun size tube.

    I injected some into 5/8 clear vinyl tubing, then immediately used compressed air to blow out the silicone to make tubing. The length of the new tube will be about twice the length of the silicone sitting in the vinyl before its blown out.


    Here is a suggestion for getting more silicone into the tube. If you use a syringe on the other end of the tube to create a vacuum, when you go to push the silicone in the other end you it will help pull the silicone further into the tube.