Knutson's technique utilizes:

Method of application of neutral sodium fluoride according to Knutson’s technique: Treatments are given in a series of four appointments. At the initial appointment, the teeth are first cleaned with aqueous pumice slurry and then isolated with cotton rolls and dried with compressed air. Teeth can either be isolated by quadrant or by half mouth. Using cotton-tipped applicator sticks, the 2% sodium fluoride solution is painted on the air-dried teeth so that all surfaces are visibly wet. Then with the teeth still isolated, the solution is allowed to dry for 3 to 4 minutes. This procedure is repeated for each of the isolated segments until all of the teeth are treated. A second, third and fourth fluoride application, each not preceded by a prophylaxis, is scheduled at intervals of approximately one week. The four-visit procedure is recommended for ages 3, 7, 11 and 13 years, coinciding with the eruption of different groups of primary and permanent teeth. Thus, most of the teeth would be treated soon after their eruption, maximizing the protection afforded by topical application. Essentials of preventive and community dentistry  Soben Peter  5th edition