Determine a manufacture claims its cleanser works twice as fast as any other could tests be performed to support the claim?

An experiment may be set up as follows:

Equal quantities of different cleansers are used to cleanse a surface. When doing so, other variables such as the temperature of water and amount of water added should all be kept the same. The time taken for the surface to become clean is measured. If the manufacturer's claim is true, then the time taken for their cleanser to complete the cleansing will be half of that of the cleansers from competing companies.