What is “Pulsing” a Coil?
“Pulsing” a coil, irrespective of type and constituent materials, is the act of passing short “pulses” of current through the unwicked element in order to heat it slowly. The aim of this (alongside “strumming” and “squeezing” with tweezers etc.) is to eliminate “hotspots” and to allow the current to pass through the coil, making it glow evenly outwards from the centre of the element. This will prevent nasty, burnt tasting draws when in use, and stop the wicking material becoming damaged in isolated spots.
Further to this, many people who use cheaper wire of dubious origin and constitution have experienced issues with machine oil, residue and detritus contaminating the coil, and believe that by pulsing the coil any potential contaminants are burned away and nullified. This is not a problem we’ve personally encountered with our resistance wire, but we’ll look into “coil hygiene” in a later article.
What is “Dry Burning” a Coil?
“Dry burning” is similar to pulsing a coil, only this time after the wire has been put to use. Vapourising e-liquid will, after a time, cause the coil and wicking material to “gunk up” with matter that can affect the taste and performance given from your atomiser. To answer what that “gunk” is would be a lengthy exercise in chemistry and physics, but for our purpose here it will suffice to say that the manky stuff found after some time is a result of eliquid failing to vapourise effectively.
The most common cause of coil gunk is the sweeteners that can be found in many of today’s popular eliquid varietals. Alongside juices which are darker in colour, sweetened liquids are thought to contain denser, “heavier” molecules which are more difficult to vapourise completely.This means that as the liquid vapourises, those constituents which don’t vapourise entirely are left behind and maintain a solid form which then “burns” as more heat is applied to it. It will also “clog” and prevent the wicking from transporting liquid optimally and this, at least to the taste of most people, can give a somewhat overall unsatisfying and yakky vaping experience.
Most vapers will clean and reuse their coils to extend the usability and life span of their build set up, and in doing so most will “dry burn” the coils in the process. Quite how this is best done shall be looked at in a later article, but before we do that there are some things we need to be aware of before we decide if dry burning is going to be for us.
The Composition of Wire and Oxidisation.
Many different varieities of metal and alloys of metal can be used as resistance wire coils in RDAs, RTAs and other types of vaping atomiser. We’ll have a quick look at the three most common below, returning to look at “Temperature Control” specific wires (like Ni200, NiFe and Titanium) another time.
Kanthal (FeCrAl) wires are a ferritic iron-chromium-aluminium alloy, which is extremely oxidation resistant and stable right up to
temperatures nearing the melting point of 1500℃. These wires are composed of mostly iron (72%), chromium (22%) and aluminum (6%). As Kanthal is heated it becomes coated with the thermodynamically most stable oxide. Since aluminum oxide is more thermodynamically stable than either chromium oxide or iron oxide, a layer of aluminum oxide forms on the surface of this wire. This “protects” it and provides longevity under thermal duress. Coupled with its malleability and relative low cost, this has been the traditional material of choice in vaping for a long time, and is probably the most widely available atty wire or coil building material to date.
Nichrome (NiCr) is an alloy of Chromium and Nickel, available in various percentage mixes, the most common being Nichrome 80 (80% Nickel, 20% Chromium). This alloy is often referred to in vaping as Ni80 or N80. When heated to high “red hot” temperatures an outer layer of chromium(III) oxide develops, which acts to protect the heating element from further oxidation, making it last much longer. This variety of wire is renowned for its fast heating action (“ramp up”) and relatively lower resistance, often favoured by mechanical mod users because of its awesomely quick vapour producing effect. Popular amongst the cloudsbroclouds community contingent, pariculary as a ribbon or flat wire.
ii) Stainless Steel
“Stainless steel” is the generic term used for a number of different alloys used primarily because of their resistance to corrosion. Steel is an alloy of iron and carbon, and when at least 13% of chromium (Cr) is added to the alloy, it is then known as “stainless”, meaning that it does not rust. Other metals present in austenitic SS (the “300” numbered varieties) depend on its type. For example SS316L also contains small amounts of molybdenum (Mo – 2.5%) and manganese (Mn – 2%). These different additive metals are there to alter or give certain desirable qualities to the alloy. SS316L contains less carbon than 304 Stainless steel, which makes it preferable for higher temperature uses and exposure to corrosive element applications.
Just as in the case of Nichrome, the amount of Chromium in a stainless steel alloy is sufficient to form a protective layer of chromium oxide, protecting it and providing increased stability when heating.
Stainless Steel also has a quick “ramp up” time and a relatively low electrical resistance, making it ideal for use with mechanical devices. Further to this, it has an excellently predictable TCR and TFR pattern and is superb for use not only with straight wattage providing devices, but also with “Temperature Control” and DNA “Replay” devices such as those using DNA75C or DNA250C regulation boards. More info on this can be found in our earlier article here.
As we have seen above, all of our vaping wires occur oxidisation, and oxidisation is a desirable condition when using metals to evaporate eliquid. It protects the material to a degree and enables us to to vape using reatively stable and efficient coils. However, there is a bit of a potential drawback to this, something which is increased by pulsing or dry burning your build, and that’s them pesky things known as particulates. As chemist Miroslaw Dworniczak puts it:
“In a nutshell: dry-burning definitely changes the inner structure of the metal/alloy. This, in turn, can affect the integrity of the coil, allowing tiny metal particles to be leached by e-liquid. When the liquid forms the aerosol, some of these particulate matter may be present in it, so then it can also enter vaper’s respiratory system.”
M.Dworniczak, 2016 “E-cigarette coils from a chemist’s point of view”, https://nicotinepolicy.net/blogs/guest-blogs/23-miroslaw-dworniczak/138-e-cigarette-coils-from-a-chemist-s-point-of-view
Pulsing and dry firing a coil may cause atomic alterations in the metal, potentially allowing constituent elements/ by-products to fragment alongside dislodged oxidised matter. In effect, we potentially run the risk of inhaling deep into the lungs teeny tiny incy wincy microscopic amounts of undesirable metallic materials. This sounds like a horrendous thing, and exactly the kind of thing anti-vaping zealots may get a froth on about. But as with all things in life, context here is vital. As the Royal College of Physicians advises:
“In normal conditions of use, toxin levels… are probably well below prescribed threshold limit values for
occupational exposure, in which case significant long-term harm is unlikely………Some harm from sustained exposure to low levels of toxins over many years may yet emerge, but the magnitude of these risks relative to those of sustained tobacco smoking is likely to be small.”
“Nicotine without smoke:Tobacco harm reduction”, 2016, p79, Tobacco Advisory Group, Royal College of Physicians, https://www.rcplondon.ac.uk/projects/outputs/nicotine-without-smoke-tobacco-harm-reduction-0
Conclusion: So can we dry burn our coils then or what?
Well, being woke AF chilled out folk here at Stealthvape, we think that its entirely up to you. Although there is a risk of exposure to microscopic quantities of undesirable and potentially harmful by-product particulate matter, we believe that that decision is one which you should make for yourself. It is up to you as an indiviual to offset any potential risk of harm against the increased longevity and perfomance functionality provided by dry firing and pulsing your wire. As Farsalinos & Carvalho say:
“We will repeat our honest opinion that dry-burning the coils will not make vaping similar or worse than smoking. This is clear and there is no need for over-reactions. However…..If something can be avoided, vapers should be aware of it so that they can avoid it if they want to.”
K.Farsalinos and P.Carvalho,”Dry-burning metal coils: is it a good thing?”, 2015, http://www.ecigarette-research.org/research/index.php/research/research-2015/212-db
The answer to our conundrum then is really quite simple. There is a small risk (but risk nonetheless) of potential harm caused by dry burning and pulsing your coils. Whether or not you think the level of potential harm is negligible and worth taking in order to have a more convenient and pleasurable vaping experience, well that is entirely up to you as a responsible autonomus adult. As with all aspects of vaping, do some research, don’t be afraid to ask questions and make your own decision based upon your findings. Explore the possibilities and learn stuff along the way. And pass on the knowledge to those new to the vape community. Above all be courteous to those that may just happen to disagree.
It needn’t be a drama and it needed be a bore. Do what thou wilt shall be the whole of the law!