How we tested them

EASE OF USE We applied each product to half a clean, untreated helmet visor as per the supplied instructions and using any cloth that was included with the product. If none were supplied, we used a new microfibre cloth for each product. We also looked at how much was needed to provide adequate coverage.

EFFECTIVENESS To ensure consistency, we bench, rather than road, tested the products. We applied water from a set distance using a pressure washer in a single burst and gauged how effectively the water ran off the visor when we shut the water off. We also looked at whether any water left on beaded or spread.

LONGEVITY After the initial water application, we sprayed the entire visor for a set period of time repeatedly to assess how well the treatment lasted and how its effectiveness changed. The score here is based on the number of sprays it took until the treated and untreated sides behaved the same.

TOXICITY We considered the ingredients in each liquid, any warnings displayed on the bottles, packaging or available data sheets and the odour of the products themselves as we applied them. Some clearly showed ingredients and warnings; others needed some effort to find.