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Road Gear

Technical FAQ: Tire sealant questions

Lennard Zinn answers questions about tire sealant, tubeless tires, and whether or not it's possible to drain sealant from tubes

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Dear Lennard,
I have been happily using tubeless road tires for almost a year without a flat. I carry a spare tube along just in case, but I’m not looking forward to wrestling a tight-fitting tubeless tire off and on the rim out on the road in cold weather, should the need ever arise.

I use Stan’s No Tubes sealant. They specifically recommend against using a standard CO2 inflator to re-inflate tires because it will cause their sealant to ball up and be rendered useless. I’m wondering if I can use a Hutchinson Fast’Air Latex Aerosol Inflator out on the road instead. Is it compatible if Stan’s is already in the tire?
— Win

Dear Win,
You generally can’t count on using the same sealant long-term after having inflated it with CO2 or with a sealant-filled inflator. Here are some replies from sealant makers.
― Lennard

From Effetto Mariposa:
“Inflate and repair cartridges commonly contain liquid sealant and propane (or methane-propane mixes), a gas that turns to liquid at lower pressures (5 bar @ 0°C) compared to CO2 (around 35 bar @ 0°C). That’s why inflate and repair cartridges come in aluminum cans and CO2 comes in little steel cylinders; the internal stress the container has to endure is much less for propane. That’s also the reason why you get more inflating power from a small 16g CO2 cartridge than from a big 75ml inflate and repair cartridge, but I digress.

The expansion of a gas is an endothermic reaction (brutally said, it “sucks” heat) and the magnitude of the temperature drop is related to the initial gas pressure; because of its higher cartridge pressure, CO2 will “freeze” a lot more than inflate and repair cartridges like our Espresso.

The reason why latex sealants solidify when using CO2 cartridges is a physical one; it’s the big thermal shock, which often initiates the polymerization of the sealant. To avoid it, it’s normally sufficient to put the valve at 12-o’clock prior to inflation and let the sealant flow down to the 6-o’clock area, so that it won’t be directly hit by the cold gas. Also, reducing the inflation speed (most CO2 adapters allow it these days) will prevent dropping the temperature too much, good for the sealant … and good for your hands, if you’re not wearing gloves.

Inflate and repair cartridges, while sealant-safe from a physical standpoint, are dangerous for the sealant from a chemical standpoint, though. Besides physical shocks (thermal shocks, but also sudden evaporation — as in the case of a puncture), changes in the pH of the sealant can also trigger its polymerization. Using an inflate and repair cartridge, you’re mixing the sealant inside your tires with the sealant inside the cartridge. The mix is stable if both have the same pH (like our Espresso and Caffélatex, which have a similar formula for this very purpose); otherwise, the sealant will normally solidify in a matter of minutes or maximum a few days. This won’t prevent roadside repair, so the cartridge will serve its purpose, but you’d better wash away the sealant mix once at home and restore your liquid sealant of choice, for enduring protection.
— Alberto De Gioannini
Founder, Effetto Mariposa Sagl”

From Stan’s:
“We have not tested the Hutchinson FastAir that contains a liquid sealant. We have used the Propane Big Air and the Big Air works fine with our sealant. CO2 will get you out of the woods, but we found it reduced the life of the sealant.
— Peter Kastner
System Manager

Also from Stan’s:
“I don’t think the propane will affect the sealant. Either way, he just needs to get home. Once home, he can remove one bead of the tire and inspect his sealant. Tubeless tires are not hard to dismount if you push one bead into the drop channel and remove this bead while leaving the second bead stretched on the tubeless bench. It’s harder to remove the tire once both beads are in the drop channel. But even then, a plastic lever can remove the first bead and the second will push off with your hand.
— Stan Koziatek

Dear Lennard,
I have read a few columns about sealant, and after an encounter with some glass on a cold, rainy day, I’m keen on trying some. I read one test where the author found certain products can work quite well in latex-tubed clinchers. However I’m a bit concerned about the sealant drying out and either leaving a big clump of cured sealant in my tubes, or simply ceasing to seal any fresh punctures. Orange Seal and Bontrager TLR performed quite well in the test I’m thinking of. Do you have any knowledge about how long the sealant would last in a latex tube with a bit of either of these sealants installed? What does one do to prevent the sealant from drying out, or to rehabilitate a tube with dried out sealant?
— Cornelius

Dear Cornelius,
The sealant will stay liquid for a very long time as long as you keep the valve closed, including during off-season storage where it stays deflated. I have only used Caffelatex in latex tubes (and those are only in tubulars), since that’s the sealant that Dugast recommends for the latex tubes in its tubulars. And the sealant has lasted for a couple of seasons, when I consistently left the valve closed.

You can’t rehabilitate a latex tube with dried-out sealant in it, and removing the sealant is also not practical. I have removed sealant from latex-tube tubulars for the off-season. It is not something I’d repeat again. It required a ridiculous amount of rinsing, inflating, draining, rinsing, etc., and it stressed the valve so much that it ended up that I discovered, at the beginning of the next season, that I had created a leak around the base of the valve stem on a couple of the tubulars. I don’t recommend it.

Sealant removal is only practical with tubeless tires; wiping it out of tubeless clinchers is easy, and you can also suck it out of tubeless tubulars—namely Tufo and Clement (also made by Tufo).
― Lennard

Dear Lennard,
Now that tubeless tires have been around for a number of years I was wondering if there is a definitive maintenance routine that should be followed to insure safety and the flat-free riding that they offer.

Personally I take my tires off once a year, usually during a cold spell-inspired round of bike maintenance. More often than not, I find a small “Stan’s ball,” as I’ve come to call it, of hardened sealant in MTB tires. In road tires there can be a few pellet-size particles. I clean the contact areas of the rims, remount, and replace the sealant. I have been told by a good local mechanic that this is unnecessary and to just add a few ounces of sealant a few times a year. This would seem to make the tire set-up heavier over time and that Stan’s ball would still be inside the tire, hypothetically just getting bigger. As might be expected, searching on the Internet has yielded a wide range of opinions.

Have any recommendations or guidelines been developed by the manufacturers and/or professionals in the business of bicycle maintenance, such as yourself, over the past few years?
— Rick

Dear Rick,
The Stan’s ball appears where air is leaking out of the tire. Presumably those spots in your tire are now sealed, so they won’t tend to get bigger with the addition of more sealant. Once the liquid in the sealant has dried out, there is very little weight to be concerned about, other than large Stan’s balls. While it’s not that big a deal to pop one bead off of your tires and wipe out the old liquid and hardened sealant, your mechanic has a point; just adding a bit more sealant periodically is easier.

I’m much more concerned with leaving a tire deflated and parked for a long time, as the sealant con solidify in a long, solid puddle at the bottom of the tire, thus throwing it out of balance. Peel this out and then add more sealant.
― Lennard

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