Many people think when people use half, it means after they've mixed it. However, when I use half of my no-lye relaxer (and other ladies I know do this as well), they split the relaxer and the activator fluid BEFORE they've been mixed together; then save the other halves for next time. As long as it isnt mixed, it's fine; just split the two items before mixing them together or yes, they will indeed go bad.