VeloNews and Caffelatex

It's been almost exactly six months since VeloNews' Lennard Zinn confirmed concerns initially raised by Shimano tech reps, putting the kibosh on manufacturers' denials that the even relatively small quantities of ammonia in their latex sealants can result in serious rim corrosion.

In the same VeloNews collumn Effetto Mariposa founder Alberto De Gioannini published a letter explaining the chemical basis for the tire and rim corrosion process that can happen with other brands...and why it doesn't with Caffélatex:

Lennard,
The problem is not so frequent as the e-mail seems to suggest, but this might hold some truth as far as 'first generation' latex sealants are concerned (you can easily recognize those by the typical ammonia smell). Ammonia is used to stabilize natural latex and, although in a small concentration, it can harm both tires (depending on the rubber formulation) and rims in the long run.
See this link for natural latex and ammonia:http://www.afet.or.th/english/product/latex/

Tire and wheel compatibility was one of our main concerns defining Caffélatex formula. We only use synthetic latex (much more stable) and we've been able to avoid any additive that could damage wheels or tires; we're 100 percent rim and tire friendly.

Alberto De Gioannini
Founder, Effetto Mariposa

The complete column is available here.

Now Lennard weighs in again after some months of using Cafféleatex (in this case, for his cyclocross wheels). He reports:

So the big question I have is, why aren’t people putting sealant in their tires? Or are they and still getting flats? I know Matt was not, because I asked him.

I have six sets of cyclocross wheels – four tubular sets and two clincher sets. I run 25-30ml of Caffélatex in all of my tires. On the tubulars, I remove the valve core and stick the hose of the syringe injector over the valve. On clinchers, I use the bigger 700 X 35-42C inner tubes so that the tube is not stretched very much inside, which would open a puncture hole bigger. And I just stick the hose of the syringe injector right over the valve and shoot it right in through the valve core. The valve works fine afterward.

I chose Caffélatex because of the demos I’ve seen at bike shows in transparent tires where the sealant stays foamy. It would seem to me that this would give a measure of protection in the case of a snake bite (pinch flat), where usually you could be certain that a sealant would not seal the hole of the snake bite pair that is toward the rim. And any sealant will fill most small holes on the circumference (thorns, etc.).
I have come back from training rides on both clinchers and tubulars where there were goat’s head thorns sticking out of my tires all over the place, and I never even knew it. No air loss in subsequent days, either. It was as if I had never even hit a thorn in the first place.

By definition, water weighs 1 gram per milliliter, and the density of liquid latex sealants is bound to be similar to water. So you would add 25-30 grams per tire, and, indeed, this is the weight difference I measure. To me, this extra weight with absolute confidence of not getting flats is worth a lot. Last weekend I was running my tires at 24 psi, and I weigh 175 pounds! The weekend prior, I raced both races at 28 psi. Tubulars feel great on rough courses at this pressure, and they hold really nicely on the turns and side hills. But if you’re afraid to run them low for fear of flats, what’s the point in having them in the first place?

(Emphasis ours.) Amen, Lennard. Complete story available here.