There’s not much point in a clean window if it’s streaky.
To find which glass and window cleaners get the job done, we test them in our independent lab. Here’s how we do it.
We aim to test brands and products you’re likely to see when you head to the shops, plus some you might not be aware of.
Before we buy anything, we do our research: we visit stores, both online and physically; we talk to experts and consumers; and we ask manufacturers about their products. We want to capture new developments in the market and make sure the products we test will be available after we publish our results.
We then compile a list of products and head out to purchase them, just as any consumer would.
The lab uses special pre-soiled white ceramic tiles. The tiles are then cleaned using a mechanical scrubbing apparatus. To measure dirt removal, reflectance readings are measured before and after cleaning using a spectrophotometer. Each cleaner is tested eight times and the results are averaged for the overall score.
To test for streakiness, we clean a glass pane with each cleaner. A panel of 4 experts then assess how streaky the pane is and rank the cleaner on a scale of 0 (no residue) to 4 (very strong residue). Their assessments are averaged to obtain our streak score.