Dripping produces thicker clouds of vapor, gives a stronger sensation in the throat and makes flavors taste better, according to a study, published Monday in the journal Pediatrics.
"This study is the first systematic evaluation of the use of dripping among teens," said Suchitra Krishnan-Sarin, lead author and a professor in the department of psychiatry at the Yale University School of Medicine.
Krishnan-Sarin and her colleagues surveyed teens from eight southeastern Connecticut high schools during spring 2015.
Though some respondents did not answer all the questions, 1,874 students reported having tried an e-cigarette. More than 26% of those who'd tried vaping also reported dripping.
Being male, being white, having tried more tobacco products and using e-cigarettes on a greater number of days over the previous month were the traits likely to be associated with dripping.
What is dripping?
E-cigarettes heat liquid and turn it into vapor, which a user inhales and then exhales in a large puffy cloud.
The normal process of vaping relies on an e-cig's reservoir and wick, both of which automatically feed liquid to the heating coil within the device, minus any effort or intervention on the part of the user.
Aficionados sometimes prefer to bypass the usual battery-operated process and substitute a more hands-on approach -- essentially an artisanal version of vaping.
"Dripping is a more labor-intensive method of vaping in which the user manually applies a few drops of liquid directly to the exposed heating coil of the e-cig every so many puffs," said Alan Shihadeh, a professor of mechanical engineering and director of the Aerosol Research Laboratory at the American University of Beirut.
Shihadeh, a project leader at the Center for the Study of Tobacco Products of Virginia Commonwealth University, was not involved in the new study.
Along with a better cloud, more flavor and a stronger hit, Shihadeh said, some people prefer dripping because "it allows them to conveniently change from one liquid flavor to another without wasting liquid."
Ray Story, CEO of the Tobacco Vapor Electronic Cigarette Association, an industry group, suspects the number of teens who have tried dripping may not be as high as the study indicates.
"Do we think it's going to become a trend or very popular? No," he said. Story, who was not involved in the study, believes there will always be an extreme gro