WSS Open Source Sealant for Tubeless Bike Tires

After my experiment with inflating standard tires dry on UST rims, it was quickly obvious that I needed a sealant in order to use them tubeless.

I did some searching on homemade tire sealants and I stumbled across the WSS Open Source Sealant.

The basic recipe is as follows:

1 part Latex mold builder
1 part Slime tubeless
1 part cheap antifreeze
2 parts water

I sought to modify the recipe a little.  I am just not a fan of the extremely toxic nature of ethylene glycol, especially to pets.  The stuff is extremely sweet to them and for something that’s likely to be weeping out of the sidewalls of my tires, I don’t want the local wildlife getting a taste.

I followed the first two ingredients.

1 part Latex mold builder
1 part Slime tubeless

open source sealant ingredientsopen source sealant ingredients
I used 16oz as my “part” quantity.  Basically, I used the latex jar for measuring purposes.  I diverted from the recipe somewhat for the next two ingredients.  The latex I used was a couple dollars more than the “mold builder” stuff (this is found in the model train section of Hobby Lobby), but it doesn’t have the same warnings about ammonia as the mold builder stuff.  This one is more cryptic about its actual contents, so I’m not entirely sure if there’s ammonia in it or not.

Instead of cheap ethylene glycol (EG) antifreeze, I used low toxicity propylene glycol (PG) antifreeze.  The stuff is nearly impossible to find down here in Texas, but I did manage to find a jug at Tractor Supply.
open source sealant ingredients
For the final ingredient, I only used 1 part of water.  After adding the 1 part water into the mix, it sure looked thin enough to me.  Adding another part of water would have really thinned it out, forcing me to add more of the final product to my tires to get the same amount of overall sealant.

Therefore, my recipe ends up being this:

1 part Latex mold builder
1 part Slime tubeless
1 part propylene glycol antifreeze
1 part water

Some riders will use an assortment of glitter sizes to aid in the hole plugging properties of the Slime, which contains some fibers and rubber chunks already.  Since I don’t have any glitter (no kids), I decided I didn’t want to buy WAY more glitter than I needed for this project.  I reserve the right to add glitter later.  If you do add glitter, it may behoove you to actually use 2 parts water in the recipe.

At this point (unless you clicked the link and are reading in-depth information about others using this recipe), you’re probably wondering what the antifreeze is for.  If you’ve ever used Stans sealant or known people who have, you’ve probably heard of the legendary “Stans boogers.”


Examples of Stans Boogers abound on the interwebs.  Point is, the antifreeze is also a coolant, right?  It helps keep your latex liquid so it can seal your tire in arid conditions giving extended time between sealant changes.  There are reports of the WSS Open Source goo lasting a full year.  In addition, riders in cold climates have also noted their sealants freezing in the wintertime.  Antifreeze prevents that from happening, also.  Note that the Slime already contains PG, but with the addition of straight latex, it’s important to add some more to deal with dilution issues.

Once you’ve got your WSS Open Source Sealant mixed up, it’ll look something like this:
open source sealant

You’ll want it somewhat thin so it can easily coat the inside of your tire.  You also don’t want it to goop up in one spot because it’ll throw your wheel out of balance with the concentrated weight.  With the jug I have it in, I can easily give it a good shake before dispensing to make sure I disperse the chunks inside it and I get some in my tire.

If this works out, I’ve got two more bikes in my garage that will probably end up getting a tubeless conversion.  Those other two bikes have standard rims, however, so I’ll have to use a full ghetto system or buy some rim strips to seal the spoke holes off.

7 thoughts on “WSS Open Source Sealant for Tubeless Bike Tires”

  1. I have been really happy so far using the gorilla tape rim strip with a true UST valve stem. I watched a youtube video where they did the gorilla tape rim strip but I opted for the more solid build UST valve stem. Only thing it doesn’t give you is a bead seat. Haven’t tried it yet but since I had to use two wraps of gorilla tape, I considered putting a first wrap within about 1/8″ of rim edge and second wrap all the way to edge in order to leave a little bead seat.

    1. I haven’t used it on carbon wheels, but I don’t see why not. Nothing especially troublesome in there from a reactivity standpoint.

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