Stain removal depends on three things: Agitation, water, and chemistry. Anyone who ever blotted out a food stain from a shirt in a restaurant bathroom knows that different stains require different methods of removal. That's why we used stain strips to quantify how each cleaning agent performed.
These strips are mechanically coated with common household substances like cocoa and red wine, and the three tests were performed with the Kenmore 25132, a top-loader very similar to what's found in a lot of U.S. homes. We set the Kenmore to its highest temperature setting and used the Normal cycle.
After each test cycle, we analyzed the stain strips with a photo spectrometer to determine how much of the stain had been lifted. Since we know what the color of the cloth is underneath all the stains, we calculated how close the cleaning agents came in restoring the test strips to their native state.