Introduction: Homemade Silicone O-rings and Tubing

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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!

Picture of 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!)


jimwi (author)2017-07-20

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

jj8080 (author)2017-01-25

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

CaptainChrisso (author)jj80802017-01-26

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

Trainrek7 (author)2016-12-14

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!

Trainrek7 (author)2016-12-13

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?

CaptainChrisso (author)Trainrek72016-12-13

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!

PhilH84 (author)2016-11-21

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

Ruettiger (author)2016-08-19

this is simply brilliant!

Mjtrinihobby (author)2016-05-16


JamalD1 (author)2016-01-28

This is the best method for making o rings

FrankenPC. (author)2016-01-20

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!

paappraiser (author)2016-01-18

I love this@!@

ceremona (author)2015-12-30

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

CaptainChrisso (author)2015-12-15

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.


pinkham21 (author)2015-06-30

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.

CaptainChrisso (author)pinkham212015-12-15

Hell yes! Maybe an automotive vacuum pump, anything would help. Thanks for the idea!

Scumbdyoit (author)2015-12-14

McMaster Carr ( sells o ring cord stock (round, square, x-shape) by the foot (3 ft min) in 11 different materials (including silicone), 1/32" to 1" diameter, eight colors. For example, 1/8" round black silicone stock is 84 cents per foot.
Could you use a short piece of tuning to glue the ends together in perfect alignment? Stick one end of cord in tube, apply silicone glue, stick other end of cord in other end of tube. Where cured, cut the tube away carefully. (I haven't tried it.)

Good call! If joining two ends of tubing, that is the better way!

lukemarq (author)2015-08-22

pretty damn cool

FerZF (author)2015-06-10

broadbent (author)2015-05-17

A pinch of salt to an old instructable: making a slanted joint increases the bonding area making it stronger, & allows for a better fitting of the joint than a perpendicular cut. Saludos!

HAL 9000 (author)2015-05-02

Came here looking for a way to make custom sized o rings to seal a hookah I'm building. I plan on buying a length of silicone cord (I need to make a lot) but need a way to make it into a ring. This looks like a perfect method to join the ends together and very easy! Thank you so much!

CaptainChrisso (author)HAL 90002015-05-08

Glad I could help! Enjoy that hookah! Love to see a pic...

NelsonStudios (author)2015-04-16

Not sure if I ever sent you what I made using your ideas but I did give you a shout-out in the video. Thanks again.

I'm so glad the gaskets worked out! If the gasket ever breaks, or if there is a defect, you could put it back in the mold and re-do the bad section. I noticed the the gasket picked up the red tint from the candle wax. Its a surprise sometimes as to what the silicone will do next to different substances (like acrylic paint or cornstarch)

Thanks for the shout-out! Love the truck too!

oringcord (author)2015-03-27

i also use this way to make an o ring

obertie (author)2015-02-15

You could probably get away with moulding the O ring using a rolled up piece of paper coated in wax or PVA. because the tube looks difficult to get off. you can coat the tube with something i didnt check your guide. i would use a paper for making pvc cord and then join the 2 ends with something.

CaptainChrisso (author)obertie2015-02-15

Paper will work, ive used water to kinda dissolve the paper after the silicone cures. The silicone copies the texture of the paper giving a matte finish that looks nice. Wax paper works for for most silicone, automotive gasket silicone will stick to wax paper. Saran wrap or cling wrap also will not bond with silicone, used that for some neat looking shapes.
so much fun!

AaronL3 (author)2015-02-10

Brilliant idea. Will the joint in these O-rings stand up to the pressure and pulling that might happen when the when they're placed between to parts that screw together? I need a large (~7" diameter) O-ring for a cover that screws onto a container but I'm afraid that when I screw the cover on the O-ring might separate at the joint.

Maxamil (author)AaronL32015-02-15

If you worry about an O-ring pinching or tearing you can add a little lubricant. The skin is important to it's integrity. So I could add that after removing from the vinyl tubing and gluing you should let it rest for awhile longer before using.

CaptainChrisso (author)AaronL32015-02-10

Thank you!

The joint if done correctly is just as strong as the o-ring itself. I have pulled some apart to test them, and they occasionally break at the seam, but only if there was an air bubble or some other defect there, and only when pulling pretty hard. I created these o-rings for a PVC tube submersible camera housing, and the o-ring sat between two surfaces: a PVC Pipe cap, and PVC coupler piece, and around PVC pipe. This sounds kinda like what you are doing. The o-ring can definitely withstand being twisted against two surfaces. I twisted the cap of this housing on as tight as I could. My Video camera survived 35 feet under water!

Good Luck

- Chris

AaronL3 (author)CaptainChrisso2015-02-11

Great. Thanks for the reply.

Maxamil (author)2015-02-15

I liked this Instructable because it taught me and I enjoyed your fun in making something that might otherwise cost so much (because it has to be warehoused, entered to stock and marketed) that it is not feasible to build or repair an object that is worth far more than <$1 glob of silicon sealant and a short amount of your time. Thank you.

void_9891 (author)2015-02-06

I tried to blow the silicone out with 100 PSI but had no luck until I heated the tubing/silicone in very hot water. Then it worked well.

dragon fllyer (author)2014-05-26

I made a mold for a silicone` O ring using a method I came across for molding chocolate! Put a flat layer of brown sugar (or cornstarch or icing sugar, apparently, but they're messy...) on a plate. Then carefully press whatever you're molding into the surface - I dipped in the top of the container I was trying to make a seal for. Then I used a syringe to lay down a small bead following the indentation. It would have worked better if I had a steadier hand and more experience with this kind of thing. The vinyl tubing might be more in line with my skill level, but I think it would be hard to produce a 1/16th inch O ring that way... (But if you can self-glue the silicone, I wonder if you could just lay down a straight bead and then join the ends...)

You could just cut the tip of a syringe off to the diameter you want, and then extrude the silicone onto something that won't stick. You might have luck using water! Water will speed the cure and not deform the round profile of the oring. You could even manipulate the silicone into a straight line while it floats on the water.
Have fun!

Oh, I hadn't thought of water, but that does sound like a fun experiment. I tried drawing a circle the right size and laying the silicone bead on wax paper taped on top of it, which was sort of cool and again would have worked better if I had a steadier hand. But in the end I laid a gasket on the inside of the lid of the container, and it didn't leak even after being submerged for several hours! (It's for a geocache...) I have a feeling it won't be a long term solution because the silicone doesn't stick to the plastic very well. More fun experimenting!

CaptainChrisso (author)2014-05-29

To all commenters: just found a new way to rapid cure silicone! Acrylic paint. I just squeezed some silicone into a ziploc bag and then added few drops of colorful acrylic artist paint. I closed the bag and mixed up the ingredients. After a quick mixing I cut a corner off the bag and squeezed it out like a pastry bag. It changed the color of the silicone obviously, and it starts curing almost instantly so don't waste any time. In fifteen minutes my blue silicone chunk was completely cured. And it seems to actually be stronger than bare silicone... Maybe the acrylic polymer strengthened it?
It didn't take much acrylic paint to set the rapid cure, prob only needs a few drops per golf ball size blob.
You gotta try this!


gwsmyda (author)2014-02-12

Great instructable. I used a 1/4" OD tube to create an o-ring for a leaky OtterBox pursuit 20 case after I already voided the warranty. A bit of silicone lube from Ikelite helps it to slide right into the groove.

CaptainChrisso (author)gwsmyda2014-02-12

Man that's great! Thanks for the comment!

joe7sch (author)2013-10-27

Heat will speed up the curing time... carefully...

jduffy54 (author)2013-09-16

If you want to speed up the drying time, mix about 2 parts silicone, 1 part cornstarch, and (if you want to, you don't need to), 1 part mineral spirits. The drying time will drop to ~ 1/2 an hour for any thickness even several inches.

CaptainChrisso (author)jduffy542013-09-17

Thanks for the comment! Another maker suggested the corn starch, which works great, I will try the mineral spirits next...never thought of using that since it works for cleaning up. Side note; silicone cured with corn starch is irresistible to roaches. Its not like there's better stuff to eat in my workshop, but they go for the silicone anyway.

padbravo (author)CaptainChrisso2013-09-28


are you for real? jajajajajajajaj.... so, it could be something to use to trap them?

jduffy54 (author)padbravo2013-09-28

Personally, I've never had a problem with that, or any bugs eating my molds.

padbravo (author)jduffy542013-09-28

I'll find the way to use that knowledge on some instructable...

AlbinoMoose308 (author)2013-07-14

This is a fantastic instructable! *favorites it imediatly*
I had no idea silicon made such a great seal
I can finally start making an HHO welding torch!

Nachtengel (author)2013-06-20

Could you inject a little at a time say an inch, let it cure blow it through a bit and then inject more building up the length required gradually.? Would this solve the long cure time for larger diameters? Thoughts?

That is not a bad idea, and pushing the wet silicone through the vynil while it is plugged with a cured section should not be a problem, escaping air should get by. Only problem might be getting new silicone to mate with the old without any air pockets.
Where did you find o-ring cord? :-)

P.s. I bailed on making any more camera housings, go-pro makes my hobby obsolete!

Nachtengel (author)Nachtengel2013-06-20

Also you can buy o-ring cord in various diameters from 1-10mm in lengths of 1metre up. I presume you can still use the method shown to form the cord into a ring.

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