Our cleaning score is a measure of how well the cleaner removes soft soap scum.
Most New Zealand cities have soft water, which means soft soap scum is the most common residue in bathrooms. We use a combination of soaps, synthetic sebum (body oils) and carbon black (which provides a dark colour, so cleaning can be measured) to simulate the effect of soap scum.
How we test
Soap scum is baked on to tiles, then scrubbed with the cleaner for 10 strokes using a mechanical arm. The reflectance of the tile is measured before and after scrubbing. Each cleaner is tested eight times and the scores are averaged. Our lab follows the manufacturer's instructions for application times.
How we choose what we test
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.