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Campbell's 1932 "Improvements in Dental Spraying Apparatus"

The Sparklets Dental Hygienator was the size of a flashlight with a length of 10". The

CO2 cartridge is inserted into a holder and the rubber bumper is depressed to start

spraying from a thin tube with a pinpoint. On May 18, 1933, Campbell was granted

British Patent No. 392,433.

By 1935, Hunter was addressing problems

with capsule stress and alignment. With

assignment to Sparklets Limited, he filed for

a patent for a "Metallic Bulb and Holder"

which is easily recognizable today. Hunter

added a "transverse depression or

depressed band around the body." This

added strength and the capsule rested in a

rib in its holder. This ensured that the pin

would accurately center on the bulb.