Each knife was also evaluated by our in-house ergonomics expert, Dana Keester, to see what factors contribute to good and bad knife design. To do that, we used a basting brush to paint oil on the hands of the participants, and asked them to repeat the tests, noting whether each knife slipped or became difficult to handle. Then we evaluated whether performance and design would hold up with slippery hands, similar to what might happen if you were working through a chicken breast.