June 22, 2018 17 min read 1 Comment


By: Dave Buckley

Advisory Note: These are observations that I’ve been able to make by extrapolating various points of information across; multiple sciences (metallurgy, electrical engineering, physics, etc.), medical articles, research papers, industry professionals, health care professionals, and countless others. While I greatly enjoy learning new topics, studying new information and learning the details I am not an industry professional within these various sources. This information is based upon my personal observations and understanding of each of the various scientific points that is applied within each vapor product. My intent here is to simply open the conversation and call attention to a problem that has been plaguing the vaping community for some time. It is my hope that those dedicated exclusively to the sciences will be able to use this information to continue the mission of Harm Reduction.

 What vaping is...

Vaping has revolutionized the way many adults choose to use nicotine. By providing these users with the ability to choose a path that leads away from traditional tobacco consumption. It provides adults with an easy way to control their nicotine intake, and if they so choose, and opportunity to remove nicotine as part of their daily lives.

This is the correct step and one we should have taken many years ago[1] there are some universal principles that the industry and the consumers should be aware of. This of course is the advantage vapor products have over traditional tobacco as its easier to remove an ingredient from a recipe than it is to remove a chemical from a plant.

“I don’t vape dark liquids, they burn out my coils.”

To help identify some of the more pressing issues within the vaping community we’ll first look at e-liquids, mixology, content and flavorings. A lot of consumers, and professionals believe that the coloration of the liquid will clearly indicate if the flavor will be a “coil killer” or cause the coil to burn out prematurely. The reality is, this effect is based purely on the flavorings used by the E-Liquid’s manufacturer. As the coil heats up the sugars of the flavorings will begin to caramelize onto the coils, creating a black film. This caramelization will continue to build until eventually the coil fails, or the caramelization begins to burn (as it has a higher carbon content).

The discoloration of the liquid is a natural byproduct of an aged flavor. Nicotine, will oxidize over time causing it to discolor into a yellows or sometimes brown color. In general, this coloration will get darker with age, and nicotine strength. All e-liquids benefit from aging, and in the industry, we refer to this as steeping. Ideally each bottle should steep for a minimum of 2 weeks prior to the customers purchase. Some flavors however will need more steep time, for the flavors to come through. This is also why most e-liquids have a small amount of discoloration to them.

“This brand is better than this brand”

Most people firmly believe that one device is better than the other, because of one reason or another. In truth all devices currently operate under the same basic principles; A battery, A heating element and Liquid are all that is required to vape. Devices, brands and features provide the user the ability to customize their vaping experience, although most users are not aware of the effects or impacts of using one system over another.

In the end there are only 2 types of systems available, they are either Standard or Sub-Ohm. A standard device will generally produce a smaller volume of total vapor and is typically paired with higher levels of nicotine. A Sub-Ohm device will produce much larger volumes of vapor and is generally paired with lower levels of nicotine.

In truth the real, only variance across the manufacturers comes down to the coil design and how it is used. Each manufacturer has their own designs on air flow, juice flow, wicking, and how much current will go through the coils. It is these coils that are one of the 3 core ingredients that are the achilleas heal of the vaping experience.

“Factory tanks and coils are safer to use then RDA’s, RTA’s and other drip like systems”

Most people believe that by routinely changing your coils you are creating a safer vaping environment and minimizing exposure to any potential of potentially hazardous materials. This is only partially correct, and there is a large amount of emerging studies to outline the reasons why.

The core component of a factory coil that requires it to be replaced frequently has almost nothing to do with the coil itself, rather it is the cotton. This wicking material, uses the capillary effect to bring liquid to the coil and over time will degrade and decay as it is exposed to heat. If a material were available that was able to withstand exposure high temperatures, and last longer it would become less hazardous over time.

This next part sounds completely backwards, and completely incorrect at first, yet when you begin to review the principles you begin to understand why an older coil (note: the metal portion only) is better and less hazardous to use.

The universal truth is that all of us, live in an oxygen rich environment. The problem that oxygen creates is oxidization, also known as rust. Over time coils, be they Stainless Steel, Kanthal, Nichrome or Titanium will oxidize which will cause heavy metals to be released from the coil. These oxides are created as a byproduct of heating a metal coil with an electrical current. To understand how this works and why we need to explore the coil at the molecular level.

When a positively charged proton is flowing through the coil it is much like a ball rolling through a pipe. It enters one end and exits the other, this would represent a coil with no resistance. If we were to add some impurities to slow this ball down it would then begin to produce heat (it is the friction of the positively charged proton against the impurities such as iron, chromium, or nickel which generates heat), the more the resistance the slower the ball moves the less heat is generated.

Now that we understand how the current flows through a coil, lets now understand how the coil interacts with the electrical current. As the coil heats it becomes softer, which makes it easier for the metals causing the resistance to be pushed out of the coil. Much like a pile up on the interstate, these molecules are projected out of the coil when the coil is hot. Similarly, the hotter the coil the more metals are released. As a coil ages more and more heavy metals are released, reducing the amount of available heavy metals that can be released in the future.

Factory coils, made coils will typically always have a higher level of heavy metals and or other gases that are released from the manufacturing process. These coils are typically not pre-fired prior to being placed into the coil housing and packed with cotton. As a result, the initial fire from these coils may cause heavy metals, gases and other substances to become trapped inside the cotton. This means the user is exposed to more heavy metals, and other substances over a period.

By comparison, hand-built coils are pre-fired which means any remaining factory grease, or other substances is generally removed. However, this does not exclude them from releasing heavy metals. It does however create the opportunity to remove or reduce heavy metals. Most users who use hand-built coils will continue use long after two weeks. Which means that the coils are releasing more and more oxides, which initially is potentially more harmful although with extended use becomes less harmful.

“Okay new coils are bad, old coils are good? I’m so confused how should I vape?”

The foremost complaints from researches and those studying vapor products directly relates to the coils, how they are used and how they are maintained. Of the studies that have been reported, and reviewed by their peers, scientists and medical professionals the two main concerns are; Heavy Metals and Formaldehyde. Unfortunately, most researches, medical professionals and other bodies who are investigating vapor products have minimal understanding of how most of use these devices. To understand what they are saying, you need to review their finding and compare them to current behaviors by the way actual adult vapers use their devices.

To reduce the volume of heavy metals each coil, needs to go through a very specific and meticulous process. Before we review each of the required steps and why they are required let’s review what happens inside the actual coil itself when it is being used.

On the far left of the chart below[2] we can see a diagram with various colors accompanied by an example of the structure inside the coils. A new coil will be fragmented, as the raw metals are formed into a shape, and have not yet been heated or had a current applied to them. As the coil is heated the characteristics of the coil change, until eventually when it has been heated enough the molecular structure of the wire begins to take on a rigid crystalline shape.

This shape optimizes electrical flow by moving the impurities (things getting in the way of the ball) to the outside edge of the coil. In effect this is the same process as a blacksmith, hammering out a piece of metal. By changing the molecular shape of the metal, it becomes more rigid and durable. Within the wire itself the movement of these molecules to the exterior of the wire allows it to become much more like a pipe. Allowing the current to flow through the coil easier and ensure that the resistance is more even throughout the entire coil.

As you can see by the chart to achieve this change inside a coil the wire itself must be heated over 2,000 degrees Fahrenheit. This requirement is what makes factory coils much more likely to be hazardous then hand built coils, as unfortunately Cotton tends to burn at these temperatures.

“I’ve always been told that super heating your coils is a bad thing, that isn’t true?”

It is both true and not true, and depends entirely on the context of the device, its coil and how it is being used. Historically, vapor technicians may have advised not to super heat the coils as it will cause metal oxide, or other oxides (such as nickel or chromium) to be released from the coil and inhaled by the user. The Trick here is, to super heat the coil when you are setting up your coil, not as part of your daily use.

After the coil has been super-heated and adopted a crystalline structure the coil will fundamentally change in its performance, behavior and flavor. The purpose of doing an initial super heating is to minimize the potential for any heavy metal fragmentation. Beyond the point of setting up the coil, users should ensure they are keeping their coils colder and not any hotter than a dull orange or roughly 1,200 degrees Fahrenheit.

Its incredibly important for those who participate in vape sports such as cloud competitions or trick competitions to be aware of these concepts and to ensure they are minimize the risk of potential harm to themselves. These users will attempt to push the envelop and balance the temperature of the coil with the vapor production from the atomizer to achieve the greatest potential cloud. As you can imagine there is a greater potential for harm among this demographic then there is among your standard vapor product user.

“Couldn’t something else be causing heavy metals to show up in test results? In the juice maybe?”

If we look at each of the components of the vaping experience individually there are very few options. For heavy metals to be detectable and traceable there must be a component that continues to release heavy metals in most of the current devices on the market. The only constants in this equation would be; a power source, wicking material, e-Liquid, or atomizer. The power source for most devices is stored independently of the tank, or atomizer assembly, and does not have components that are directly involved during the inhalation process (i.e. you are not pulling directly off the battery). The wicking material is most commonly a form of cotton which does not naturally contain heavy metals. E-liquid was for a time thought to be the cause as there are no standardized practices for manufacturing. This lead to countless E-Liquid companies testing their liquids to ensure there was no heavy metals. At the time and currently e-liquids continue to be tested for heavy metals and continue to yield negative results.

Its worth noting, the industry learned long ago about heavy metal contamination in liquids. Originally the company Cuttwood, which produces a flavor Unicorn Milk, used a bright pink coloring agent as part of their recipe. As consumers began to question the content of their e-liquids, concerned over diacetyl, acetoin, heavy metals and other potential contents. When Cuttwood tested their flavors, they were not pleased with their results. Multiple flavors had diacetyl and Unicorn Milk contained Titanium Dioxide a substance that is potentially harmful to lung tissue.  Cuttwood went back to the drawing board and re-mixed all their flavors to minimize the potential for any harmful effects.

This leaves the final component, and the most likely culprit. The atomizer uses one or more pieces of wire made from either; Kanthal A1, Stainless Steel, Titanium or Nichrome. While there are other wire types out there, none are as relevant as these four within the industry. Each of these wire types is a blend of materials worked together to create a heating element. Initially these wires were used in base board heaters, stoves, toasters, and even easy bake ovens. Surprisingly Kanthal A1 is actually a mix and type of wire that has been patented since the late 1880’s and only now is research beginning to be completed on the effects of this wire as it is exposed to an electrical current.

What the emerging evidence shows[3] is that the wire releases heavy metal particulate into the vapor aerosol, and that heavy metals are present in the liquids even when using a sterile sample (i.e. pharma grade propylene glycol, vegetable glycerin, and nicotine). This is most likely due to the nature of Propylene Glycol, which attracts molecules and liquids to it, on a small enough scale this micro particulate can be easily transferred from one surface to another. As the liquid flows through to the coil, it is somewhat ‘filtered’ (this may remove some of the heavy metal particulate but not all) by the cotton or wicking material of the coil. This effectively creates a base-line level of heavy metals although in most instances these heavy metals did add to the results, their total effect was minimal by comparison.

While the tanks, RDA’s, RTA’s and other atomizers are typically made from stainless steel the wire will be different depending upon the coil. When tested these heavy metals were more present in the wires present depending on which coil was used, and what current was applied to it. This means that the added heavy metal content could only come from one place, the coil.

“So, then what is the least harmful way to vape?”

The first step is to simply be aware of it, and be supportive of manufacturers, vendors, retailers and distributors who are actively working to make vaping as safe as it can possibly be. The initial goal of providing a less harmful option was only the first step. As customers, and businesses we should continue the focus on harm reduction and taking reasonable steps to reduce the potential harms to Vaper’s, those around us and our communities.

We all know of companies within the vaping community that tend to ‘thumb their nose’ when approached to either change their content or their packaging. While there is room for some jocularity and humor within the vaping movement this should similarly be taken with a splash of levity. Forgoing the obvious packaging scandal, the FDA has just launched[4], let’s look at the basic mixology of the liquid. On one hand companies like Cuttwood represent the correct course of action to take, recognizing a potentially hazard ingredient and working to remove it prior to any potential health concerns or risks being raised. By comparison some companies go out of their way to intentionally add known potentially hazardous ingredients into their e-liquid and currently holds the record with the most Diacetyl at 1,867 parts per million[5].

As an industry our focus should continue to be on continuing to make vapor products as safe as they can possibly be to minimize the harmful effects of traditional tobacco consumption.

“Okay honestly, how did you figure all of this wire stuff out?!?!”

As a coil builder I’m always looking for that perfect coil, the most photogenic one I can possibly make. With some builds, doing a pre-fire helps them gain a natural coloration after it cools (as seen below). While working on a series of coil builds for an upcoming article, I became curious on what specifically causes the discoloration. This discoloration, while visually appealing is quite hazardous to the vapor and is almost all (if not entirely) oxidation from the coil. This is oxidation which has been removed from the internal structure of the wire by heating the coil and is likely the most potentially harmful time to use a coil. This oxidation, is free floating, meaning it is not attached to the coil. Over time while the user heats and vapes off the coil this oxidation, or heavy metal fragmentation, is inhaled by the user which can cause a series of changes in the users vaping experience that most of us have come to expect as the normal. This fresh coil feeling, and taste is potentially, quite harmful.

The various oxides that are released from the coil are a by product of running using metal wire to generate heat. As the positively charged Electron races down the coil, from the positive to the negative end, it will run across various impurities. These impurities create friction as the Electron passes by the impurity, which causes the creation of thermal energy (aka heat). It doesn’t take to much time to realize that a force of current traveling at near light speeds, when impacting a non-moving object is going to cause some violent reactions. Within the coil this reaction is the release of heavy metal particulate. As the coil ages the volume of impurities goes down, the Ohm’s change, and so does the flavor.

The good news is there is a way that you can reduce or minimize the volume of heavy metal oxide you are exposed to, so long as your using a rebuildable device.

“Wait… so I can science this at home?”

That is entirely correct, there is a process that you can try at home to see the differences between a properly setup coil that minimizes exposure to heavy metals, versus a standard coil. The results from my tests were surprising both for myself and those who participated. While there are countless ways to perform the process of de-oxidation I elected to use Vinegar or Citric Acid as both are Generally Considered as Safe (GCAS) as opposed to some of the more abrasive and toxic chemical solutions.

To do this, you will need the following materials:

  • White Vinegar or Citric Acid (not should not contain glucose)
    • This will be used to create an acid bath to remove the Oxidation
  • Tooth Brush
    • This will be used to clean the coil prior to use
  • Distilled water
    • This will be used to remove the acid bath
  • Coil Jig
    • To ensure uniformity of the coils
  • Ohms Resistance Tester
    • For safety, as well as to see the difference between the coil
  • 2 regulated devices
    • These will be used to vape from
  • 2 RDA’s, RTA’s or RDTA’s.
    • For the best results I recommend using identical RDA’s where possible
  • 2 Pieces of wire at least 6” in length
    • Kanthal A1 or Stainless Steel 316 L of equal gauge and length
      • For added fun do one set of each
    • Ceramic Tweezers
      • To hold the super-heated coil in place
    • Pliers
      • To remove the super-heated coil without burning yourself
    • 1 piece of Tupperware with lid
      • To store the coil while it soaks in an acid bath


  1. Build 2 basic 5 wrap coils
  2. Install one into your RDA and set it up as you normally would
    1. Fire, wick and set up this coil as you would normally. Do not juice this coil yet as it may impact your results.
  3. With one of the coils place it into your RDA and ensure it is firing evenly as you normally would
    1. Using a pair of ceramic tweezers hold the coil in place and super heat the coil until it becomes white hot.
      1. This should be about the coloration or time that it becomes hard to look at the coil due to the large volume of heat and energy being released
      2. Be careful not to move the coil during this step; the metal will be extremely soft and pliable, which may cause it to break or melt completely
  • It is for this reason that I recommend doing this process on a regulated device only
  1. Cool off the coil
    1. There are a few ways that you can do this, and each will have a different effect on the metal of the coil, this process is called Quenching.
      1. Quenching your coil in Cold Salt Water is the preferred method as it will create the hardest barrier on the exterior of the coil.
      2. Cold water is the middle of the road option, it will create a somewhat hard shell on the exterior of the coil, although not as hard as Cold Salt Water
  • The most common option is to let the coil air cool, this will work although it produces the softest barrier which may still allow for heavy metals to escape from the coil.
  1. Place the super-heated coil in a bath of Citric Acid or White Vinegar for 5 to 24 hours.
    1. For Citric Acid: use 20% Citric acid and 80% distilled water
    2. For White Vinegar you can place the coil directly into the solution
  2. After the coil has been soaked for at least 5 hours remove the coil and rinse it with distilled water.
    1. Be careful not to touch the coil as your finger grease can re-introduce contamination that may cause further oxidation and heavy metals to be released
    2. Scrub the coil using a clean, sterile tooth brush and distilled water
    3. Do not attempt to use soap or any other cleaning agents
      1. If it goes on the coil it goes in your lungs
    4. Be as thorough as possible and attempt to remove as much coloration as possible, if you find your surface getting to dry to clean add more distilled water
  3. Setup both coils side by side, using the same airflow, wattage, and settings
  4. Prime both coils using the same flavor
  5. Vape

What did you find? How did the flavor change? Did you find that you preferred one coil over the other?

“The results are in!”

When I conducted this study, I used White Vinegar and every participant was able to immediately tell that there was something different about one of the coils (and no one stated they could taste a vinegar flavor note). To ensure I was getting accurate results I did a double-blind survey with both 20 Gauge 5 Wrap Kanthal A1 and 22 Gauge 6 Wrap Stainless Steel 316 L and here were the results from my findings:

Wire: Kanthal A1 20 Gauge

Upon completion of the acid bath I noticed the coil fired in a completely different manner. Rather than heating from the center out the coil heated in its entirety evenly and smoothly almost like a Stainless-Steel notch coil. I suspect that the process of super heating the coil, into a more crystalline shape at the molecular level increases the coils ability to generate thermal heat and maximizes the speed at which the positively charged proton can move through the coil.

Of those surveyed 80% could detect a noticeable difference in the way the coil produced flavor, and the volume of vapor. It was reported that brighter flavor notes, (such as blue raspberry, and citrus notes) became more mellow and the background flavor notes (such as creams and custards) were brought more to the foreground. Overall 60% of the participants stated that they preferred the coil with the White Vinegar, over the standard coil. The 40% who preferred the standard coil stated that they enjoyed the brighter flavor notes and new coil ‘hit’ which the acid washed coil did not have.

Wire: Stainless Steel 316 L

More so than Kanthal the Stainless Steel caused the flavor to become more consistent across the entire experience rather than highlighting any one flavor. In our flavor tests we were able to highlight some flavorings we wouldn’t normally bring to the foreground (such as Marshmallow or Cream Notes). Much like the Kanthal A1 wire the Stainless Steel 316 L also changed in how it fired on the device, providing a more consistent and even heat across the coil.

Of those surveyed 100% could detect a noticeable difference in the way the flavor was delivered, and 80% preferred the acid washed coil. Each stated that the experience between the flavors was “Night and Day” with the standard coil only producing the brighter flavor notes while the soaked coil produced an even well-rounded flavor.

“Okay so then what does all of this mean?”

Long term I expect that we will continue to see growth and evolution as vaping continues to grow, and more adult nicotine users choose to move away from traditional tobacco. As we continue to grow, so to will our knowledge and understanding both technologies applied and its interactions with the Human body. What we do know, is that coil technology needs to improve to increase safety to the end consumer, and what we will need is a continued effort from the vaping community to ensure the vision of harm reduction doesn’t get snuffed out.


[1] Vaping was fist invented in 1963, shortly after Readers Digest published the ground-breaking article revealing the truth of tobacco consumption. Battery technology was not capable of holding a large enough charge to be


[3] Metal Concentrations in e-Cigarette Liquid and Aerosol Samples: The Contribution of Metallic Coils:  https://ehp.niehs.nih.gov/ehp2175/

[4] FDA warning companies to stop packaging that is appealing to children: http://www.businessinsider.com/fda-warns-vaping-companies-stop-candy-packaging-2018-5

[5] Diacetyl content by brand: https://vapebeat.com/health/is-ejuice-safe-vaporshark-diacetyl-acetyl-propionyl-study

1 Response


June 26, 2018

Very interesting read. Thanks.

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