Dr Mirosław Dworniczak, a chemist who became interested in vaping after quitting smoking a few years ago, has written a blog post on the Nicotine Science and Policy Blog about the common practice of dry burning. Dry-burning occurs when a lot of power is applied to a bare coil to heat it and “clean it up” from manufacturing residuals, and it is sometimes used for alignment and spacing. However, according to experts, this practice can affect the structure of the alloy or metal that the coil is made of on the surface, and it may lead to the production of unwanted particles that may stick to the aerosol and be ingested by the user.
Dr Konstantinos Farsalinos has previously addressed the issue of dry burning, and along with material sciences expert Pedro Carvalho, concluded that this practice should not be carried out on any type of coil. The chemical composition of heating elements used in coils consists of a resistance wire that is exposed to an electric current. Different types of resistance wires are used, and their grade and quality depend on the brand. The common types are kanthal, stainless steel, nichrome, and pure metals like nickel or titanium.
A dry burn is dangerous for three reasons. Firstly, the coating of oxidized material that forms on the surface can peel off during vaping and be transferred to the lungs, in the form of microscopic particulate matter. This particulate matter can cause allergies and may be toxic for organisms. Secondly, particulate matter can also be toxic for welders exposed to Mn oxides. Finally, a dry burn may amplify the normal corrosion process at the surface of a coil and prematurely deteriorate the quality of the heating element.
An unintentional dry burn may also occur when the e-liquid runs short in the tank and the cotton is not wet enough. In this case, it is advised to dispose of the burnt coil and to mount a brand new one. Reusing old coils is not a good idea since some level of corrosion would have probably already initiated, and the surface of the metal would already be relatively more fragile.
Despite the above, there is still no reason to believe that dry burning would make vaping worse than smoking. However, it does increase the risk of releasing potentially harmful compounds that may be inhaled by the user. In order to check the consistency of a home-made coil and to clean it from manufacturing residuals, a moderate heating of the wire may be more appropriate. Experts recommend using a coiler to build coils in a reproducible way. Ceramic heating elements are also available on the market, but testing of these elements is underway, and results may be made public shortly.