By Dr Farsalinos and Pedro Carvalho (material sciences expert)
There has been a lot of discussion about my statement during the RY4 radio interview on Friday May 22 concerning the dry burning of coils. This is a process in which vapers prepare the coil and then apply a lot of power to the bare coil (with no wick or liquid), heating it to the level of glowing red. The main purposes for doing this is to: a) check for homogenous distribution of temperature over the coil length; b) avoid hot spots; c) clean the metal from residues due to manufacturing or due to previous use.
During my interview I mentioned that it is not a good idea to dry burn the coil, not even once. Since then I have received a lot of responses, emails and requests from vapers to further expand on this, provide evidence and explain the issues related to this process. I have also received data sheets and specs of the metals used for coils, showing that they are stable at extreme temperatures (usually 1000oC or more).
First of all, I should say that the reactions from the vaping community are a bit exaggerated. I never said that by dry-burning the coil you are making vaping more harmful than smoking. Obviously some vapers who are used to dry-burning their coils for a long time did not like my statement, mostly because they are surprized with what i said. But please, consider that my role is not to say what everyone expects but to say how things are. To further explain my statement, I invited Pedro Carvalho a material sciences expert with good background on metal structure, composition and degradation. Pedro also has deep knowledge on e-cigarettes and is well-known in the Portugese vaping community and abroad. This comment has been prepared jointly by me and Pedro Carvalho.
Vapers should realize that metals used in coils have not been made to be in continuous direct contact with liquid, to evaporate liquid on their surface and to have the consumer inhale the vapor directly from the coil. This is a completely different issue from what the metal specifications suggest. It is well-known that metals have been detected in the aerosol of e-cigarettes. Williams et al. found chromium and nickel which was coming from the coil itself, although they did not dry-burn the coil. Although we explained in our risk-assessment analysis that the levels found were not of significant health concern, this does not mean that we should accept unnecessary exposure.