There is a common belief that Aquapel exposed for some time to temperatures below 0 degrees will perform less well after application to glass and that its rain-repellent effect may last considerably less time.
Until recently, we followed this warning too: we did not post the product in winter because Aquapel could encounter temperatures below zero during delivery.
To find answers, we carried out experiments.
First experiment. We placed a glass vial of Aquapel in a freezer and kept it there for three days at −18 °C. The liquid did not freeze at that temperature. We then applied it to the windscreen and front side windows of a car that had never been treated with Aquapel. Aquapel that had not been cooled was applied to the rear side windows and rear window, allowing us to compare durability on the same car used under the same conditions. After six months, we found no noticeable difference in the effect on the windows. In this experiment, the cooled sample performed in the same way as the one stored in warm conditions.
Second experiment. Aquapel was applied to an office window at +3 °C and high outdoor humidity. The next day, we poured water over the window and there was no rain-repellent effect. Aquapel must be applied strictly according to the specified procedure: to clean, dry glass, at a suitable temperature and without excessive humidity.
We used to buy Aquapel through intermediaries in Europe, but the product quality declined in one purchase. On one occasion we applied Aquapel to a recently bought car, and the rain-repellent effect was barely noticeable after just a couple of weeks. We reapplied it with the same result and began to wonder whether something was wrong with the glass. After changing the supply, everything fell into place.
Regular customers also reported uneven results: half the windows retained a long-lasting effect while the other half showed only a weak one. It is wrong to explain every poor result solely by winter delivery. We not only sell Aquapel; we use it ourselves.
From personal experience, we have also noticed that Aquapel's durability decreases slightly faster in winter on exterior mirrors and the rear window, where heating is often used.
In our experience, the rain-repellent effect was pronounced for two to six months after application and then gradually declined. On some windows, a difference from untreated glass remained visible even after two years.