We talk from Caffélatex standpoint, but what we’re analyzing here generally applies to “latex” (synthetic or natural) sealants.
The common reasons of sealant polymerization can be divided into two groups:
- physical (related to temperature changes, evaporation…) or
- a sudden drop of temperature, as with CO2 cartridges, described here;
- a quick evaporation, that’s what happens when the sealant exits the tyre through a puncture… this is a desired feature. Quick evaporation can also be artificial and unwanted, like in the “hair-dryer effect” described here.
- a change of the pH of the sealant.
We’re digging deeper into the chemical aspect.
Any sealant has its specific pH and it’s relatively stable (stays liquid, basically) as long as the pH doesn’t change or changes slowly (please note that a quick evaporation reduces the dilution of the sealant, affecting the pH… so that is a physical change that affects the sealant chemically). The easiest way to change its pH is mixing the liquid sealant with another liquid.
We call these liquids ‘sealant contaminants’, with a negative connotation, because their addition is normally an unwanted thing, with the notable exception of Caffélatex ZOT! Nano (where we use early polymerization to our advantage).
The most common contaminants are:
- other sealants: despite what reported on some forums, mixing sealants is unlikely to give the “Holy Grail” of puncture protection; most of the time it doesn’t work, or works for a limited time, shortening the life of the sealants.
Some people mix sealants on purpose, but that can also be done without knowing it by:
- adding a different sealant while topping up a tyre still containing traces of another liquid sealant (tip: in such a case, it’s best to remove the tyre, wash it with water, dry it out, then add the sealant) or
- using an inflate & repair cartridge (unless cartridge sealant and the tyre sealant have the same formula… as with our Espresso or Espresso Doppio cartridges and Caffélatex). The resulting sealant will normally solidify in a matter of minutes… or some days, as its durability is generally unpredictable.
Doing the mix while performing a road-side repair is ok, as the sealant still works as such, potentially repairing the puncture… but for enduring protection it’s better to wash away the sealant mix once at home and restore the liquid sealant of choice.
Glitters or other solid fillers are not chemically influencing the sealant, although they can create clogs or act as polymerization starters if they’re not mixed properly;
- soapy water: it’s ok to wet the tyre beads to get a better seal and achieve an easier inflation, but it shouldn’t be too much water and/or with the wrong “soap”.Lubricating the tyre beads with caustic dish-washing products (“Chante Clair” in Europe or “Dawn” in the US, just to name two common choices) is an unsuspected reason for short sealant life. We recommend using specific tyre-mounting products or mild hand soap. When in doubt, pouring some droplets of liquid soap on a spoon of sealant and letting it sit for some minutes will clarify the matter. If the sealant turns solid, use a different soap.
Also, if during tyre installation a lot of soapy water gets inside the tyres and mixes with the sealant, the increased sealant dilution will reduce its puncture-repairing action.