Most vaping devices are engineered for one-way airflow, pulling air inward across a heating element for inhalation. This system relies on a pressure differential to function correctly, often activating a sensor or drawing air over the coil. Blowing into the mouthpiece reverses this intended airflow, introducing positive pressure into a closed system the device is not built to accommodate. Understanding the consequences requires examining the immediate mechanical response, the subsequent chemical concentration, and the long-term risk of device malfunction.
The Immediate Mechanical Effect
Blowing into a draw-activated device immediately disrupts the pressure sensor, which is built to detect the negative pressure of an inhale. These sensors are calibrated to trigger the heating coil when the internal air pressure drops. Forcing air inward creates a sudden positive pressure, which can temporarily confuse or overload the sensor.
This positive pressure may cause the device’s electronics to momentarily shut off or fail to activate the heating element. In some cases, especially with older models, the forced air can damage the sensitive sensor mechanism. This damage can lead to “auto-firing,” where the device activates unintentionally later on.
Forced air immediately cools the heating coil, stressing the heating element material. The coil is engineered to reach an optimal temperature quickly to vaporize the e-liquid efficiently. Rapidly lowering the temperature prevents the complete vaporization of the liquid on the wick, contributing to a buildup of unvaporized liquid in the coil housing.
Aerosol Recirculation and Chemical Concentration
Blowing into the device forces exhaled breath, which is laden with moisture and residual aerosol particles, back into the internal components. Human breath contains water vapor and carbon dioxide, introducing excessive moisture into the coil area. This moisture buildup degrades the quality of the e-liquid by acting as an unintended diluent in the wicking material.
The action also forces residual aerosol particles and chemical compounds back through the device’s air path. Exhaled breath contains residual nicotine, flavorings, and solvents that are pushed inward. These compounds condense and concentrate on the cooler internal surfaces of the mouthpiece, air path, and coil housing.
This re-deposition means the user may inhale a higher concentration of these condensed chemicals, including possible reaction products like aldehydes, during the next use. Introducing oral bacteria and moisture from the mouth into the reservoir also raises hygiene concerns. The concentrated, humid environment creates a favorable location for microbial growth, potentially contaminating the liquid.
Potential Risks to the Device
The most common mechanical issue resulting from blowing into the device is the oversaturation or “flooding” of the coil. The positive pressure pushes the e-liquid out of the wick and into the central airflow tube, displacing the air needed for proper vaporization. This flooding causes a characteristic gurgling sound during the next inhale and can result in unvaporized e-liquid spitting into the user’s mouth.
The rapid temperature change caused by forcing air onto the hot coil leads to premature coil degradation. When the coil is repeatedly heated and rapidly cooled, the metal experiences thermal stress. This stress shortens the coil’s lifespan and can cause a burnt taste.
Forcing liquid and moisture into the device also increases the risk of damaging electronic components. If e-liquid is pushed far enough, it can reach the battery contacts or the sensitive pressure sensor’s circuitry. Since e-liquid is conductive, its presence on electronic contacts can cause a short circuit, potentially leading to device failure, inconsistent performance, or compromising the battery’s safety mechanisms.