1) If the build up is really thick, we recommend using Carbon-Off (above) to clean the oven the first time, and you may use Foam Plus (below) for each cleaning thereafter.
2) Carbon-Off is to be used on a cold oven (room temperature). Foam Plus is used in a warm oven (approx. 200-220 degrees F.)
3) The Carbon-Off (once sprayed on) needs to remain on the oven walls until surface wipes clean. This could take from 15 minutes to several hours (depending on the thickness of the build-up), whereas the Foam Plus sprays on and you wipe off almost immediately waiting only 15-30 seconds.