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To dry-burn or not to dry-burn?

The Hamlet’s choice of burning dry or not is rather a safety question than of any other concern. As recalled by the chemist, a dry burn consists in applying a lot of power to a bare coil in order to heat it and “clean it up” from manufacturing residuals. It is also used for alignment and spacing.

Such practice, according to the specialists, affects the structure of the alloy or the metal that the coil is made of in surface, and may lead to the production of some particles that will stick to the aerosol and be ingested by the user.

The question of burning dry was previously addressed by Dr Konstantinos Farsalinos who asked for help a material sciences expert, Pedro Carvalho. In their conclusions, the recommended not to burn dry any type of coil.

What is a coil made of?

The chemical composition of heating elements is subject to trends. The heating element is made 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. As sumarized by Dr Dworniczak, kanthal, stainless steel, nichrome and, lately, pure metals like nickel or titanium are used.

Kanthal is an alloy of iron (Fe, 70%), chromium (Cr, 20-30%), and aluminium (Al, 4-7%). When heated, aluminium oxides form a protective layer on the surface of the wire.

Nichrome is an alloy of Cr (80%) and nickel (Ni, 20%). When heated to so called red hot temperature an outer layer of chromium(III) oxide develops, which protects the heating element from further oxidation.

Stainless steel (SS) has been introduced lately to the vapers market. Steel is an alloy of Fe and carbon (C). The stainless property of steel is due to the presence of at least 13% of Cr. The Cr prevents chromium oxide from forming a protective layer. Some contaminants in the form of trace  metals are present in SS. The classical SS316 contains also small amounts of molybdenum (Mo, 2.5%) and manganese (Mn, 2%).

Why is a dry-burn dangerous?

A dry-burn is dangerous for 3 reasons:

  1. The coating of oxidized material that is formed in surface can peal off during vaping and be transferred to the lungs at the same time as the aerosol, in the form of microscopic particles, or particulate matter.
  2. The particulate matter can cause allergies. Ni, for example, is recognized for causing skin rash, itching, redness.
  3. The particulate matter can also be toxic for the organisms. It is, for example well described in the case of welders exposed to Mn oxides.

For the chemist, a dry burn may amplify the normal corrosion process on the surface of the coil and prematurely deteriorate the quality of the heating element. Toxic (for Mn) or carcinogenic effects (for the Cr(VI), a more oxidized form compared to Cr(III)) are improbable since the dose is very small.

Unintentional dry burn

An unintentional dry burn may also happen when the e-liquid got short in the tank and the cotton is not wet enough. Our advice if it happens, is to get rid of the burnt coil and to mount a brand new one.

Similarly, it is not a good idea to re-use old coils since corrosion has probably developed and already fragilized the surface of the metal. Exchanges of used coils between users is not recommended.

Let’s relativize

There is no reason to think that a dry-burn would make vaping worse than smoking. Nevertheless, it increases 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 appear useful, from the experience of vapers.

Those users generally advise building non-touching coils so that they don’t have hot spots. Using a coiler also helps building coils in a reproducible way.

Example of non-touching coils, with space between each wrap.
Example of non-touching coils, with space between each wrap.

Nowadays, heating elements made of ceramic are present on the market. The testing of such elements is underway and results may be made public shortly. On paper, such material appears to be a safer option compared to alloys or metals.

Since the trend, currently, is towards a safer vape by selecting the best e-liquid quality, by purchasing the most advanced mods that allow a control of temperature, why not following expert’s advices and not intentionally burn the coils?

 

  • KF95

    -___- pretty good article except for the lack of proofreading or proper grammar. oh and that last paragraph was painful… felt like i was back in highschool writing listening to classmates finish their narrative/persuasive or debatable essay.

    • Mark Vickers

      Are you serious haha. When complaining about grammar and proof reading I fully expect YOU to check your own. YOUR grammar is terrible, Get to fuck you sado

      • Juliery

        I was thinking the same thing. Perhaps he would benefit from a high school Composition 101 refresher class himself.

  • I read the article with interest. Indeed the notion of the oxide formation is correct. I do, however, take issue with this being a safety concern, as opposed to a longevity of the coil issue.
    When we consider the surface area of a coil and the depth of the layer of oxidization which occurs, then further consider the fact that only a tiny fraction of this oxidized layer may become entrained in the the vapor produced it becomes clear that we are talking about minuscule fractions of potentially harmful particulates. That this phenomena could rise to a level of harm is non-sequitur.
    However, the presence of the oxidized layer has something of a cascade effect on the longevity of the coil. Once a coil is dry-burned to clean it there is a shorter time before the coil again needs to be cleaned. The more often this is repeated the more fragile the coil becomes eventually leading to mechanical failure.

    • tatersaladcc

      Imma listen to this dude, I mean he has to be the smarter guy… He Bruce Nye, The Vaping Guy.

      • Bryan Jackson

        This comment is amazing. Job well done friend.

  • skoony
  • alexis santos

    if you don’t dry burn it…. how do you balance the coil for a dual build? for ss wires how do you find it stuck for 2yrs in a mouth for braces? just asking…

    • G Foundas

      With regard to balancing coils, and also, by extension preventing hot spots in single coils, the easiest solution is using identical length coils and making non-contact coils. Non-contact coils means that the “wraps” don’t touch, giving the current no place to short from one loop to another. In this kind of design, the current has to always flow through the full length of the coil, so if the coil is the same gauge and length, resistance will always be roughly equal.

      As for SS, same as for all of the other metals mentioned, the concern is that the heating vastly accelerates the oxidation of the metal, exposing the user to many more of the byproducts of that oxidation process at a faster rate. In addition to iron, carbon, and chrome, SS316L also contains nickel, molybdenum, manganese, silicon, phosphorus, and sulfur. Heating the metal may change the concentration of these various elements that is “available” to your juice for absorption and delivery to your body, though many of them are not present in amount that would ever be of concern.

      Ultimately, you have to use your own judgement. It’s better to know that these things are there and be able to make an informed decision than to just not worry about it and come what may.

      • Gargamelle PC

        In the last blood analysis I did, I had excess of phosphorus. I am vaping SS316L for several weeks only. I am repeating the analysis to be confirm whether I have excess of phosphorus. If that is true, it could be related with dry burning SS316L, and maybe I could try to go back to kanthal and repeat the analyses.

        • Christian Tänzer

          Very intersting – thanks for sharing! It would be great if you could keep us posted on that!

        • Jérôme Harlay

          Hi Gargamelle, the phosphorus that is tested in your blood is in the form of phosphate, an ion. The one that may be released by a resistive wire is bound to particles and in the form of atoms.
          I am not a doctor in medicine but you should ask you GP to check the level of your parathyroid hormone, Vitamin D and calcium concentration at the same time as the concentration in phosphate.

        • Gargamelle PC

          Hi Jerome and Christian,

          I repeated the blood analysis. The first one was after 4 hours without eating, but keeping vaping, and the second one was after 8 hours without eating and vaping. In the second one the phosphorus levels were OK, so I stay much more confident now that it was not important. Moreover, the calcium and creatinine levels were ok in both analyses.

  • Gen Mac

    Now my question is what about when build your own coils. For example I use a torch to heat the coil red hot to compress it with pliers or tweezers to keep the coils tightly closed. Is that better than electrically burning it or is it still the same thing and recommended not to as well?

  • Mk

    What about dry burning at 2 watts using short 3-4 second intervals. The coil doesn’t glow red and it seems to eventually get most of the gunk off. Is this any better, or just the same as regular dry burning? I’m talking about spaced kanthal coils by the way.

    (I agree in general that it’s better to minimize unnecessary risks)

  • Christian Tänzer

    Many thanks for the interesting article! I think it is wise to discuss those issues instead of denying them. Especially the vaping industry should do a more thorough job on testing and risk assessment before throwing just any new product/material on the market. As a consumer I understand that people do not care about those “minor risks”, but as a manufacturer or dealer there should be much more responsible actions. Together with my wife I just opened a vaper shop in Cologne, Germany. We are very focused on minimizing all risks and enable our customers to have the safest possible vaping experience (e.g. battery safety, liquid quality & additives, coil and wicking material). What materials would you recommend to use for the coils and wicks? Titanium and unbleached organic cotton? How would you describe the safest possible e-cig set-up?

    • Jérôme Harlay

      Hi Christian, organic cotton seems a good option associated to Titanium that further allows regulating the temperature of your coil via the Temperature Control mode that is gaining in popularity on the most recent mods/boxes. Unfortunately the inherent properties of Kanthal do not allow regulating the temperature and cannot be used with this functionality.