One thing we see when we visit customers that have used off the shelf oven cleaning products is a build-up of chemical residue behind the panels of the oven. This not only impacts the performance of their oven, but also has the potential of negative health impacts due to the heating of chemical residues again and again when the oven is used.
We hear that on average it can take up to 4 hours for a customer to clean their own oven using conventual cleaning products (usually as quite a cost). We believe it is easier (and safer) to invest in a professional service to ensure a better outcome, less time wasted and an oven that can perform at its best.
Its not very nice to use, it burns your skin, these products are also highly corrosive, which decreases the life span of your oven.