TL;DR
There is no danger of metal fumes from coils operating at or below 300C
Nickel coils run risk of nickel contamination in e-juice.
Tamman Temperature
This is the crux of my post. Tamman temperature is the lowest temperature at which atoms in a metal (e.g. metal wire) will become significantly mobile, and "evaporate" from the metal. These hot metal particles usually react with oxygen to form oxides.
http://www.che.ncku.edu.tw/facultyweb/leeyl/94 界面現象/Chapter 07 Solid Surface.pdf
The bad news: dry fire your coils with good ventilation. Not in a closed room. Preferably outdoors. Dont huff the fumes.
The good news: The tamman temperature of most metals is about 3/5 of the melting point.
If kanthal melts at 1500 degrees C, then the tamman temperature will be 900C (the metal will be orange/yellow at this temp)
If stainless 316 melts at 1400 degrees C, then the tamman temperature will be 840C (again, orange/yellow hot)
So there is no risk of metal exposure in e-cig vapour at 200-300C for any common coil metal.
This conversion does not work interchangeably from degrees Kelvin to deg. C. Should be ok for Fahrenheit/Celsius.
We've all dry fired our coils to ensure even heating. Im sure many of us have seen fumes rising from the metal once it reaches orange/yellow hot.
If these fumes are coming off the metal before it is glowing hot, it is from oil. This can be machine oil or oil from your hands.
If these fumes are coming off the metal coil when it is glowing, they are not harmless machining oil vapours. They are metal oxide vapours.
Metal oxide vapors from drying firing coils are toxic. Nickel and chrome would be two examples of this (nickel200, nichrome, kanthal and stainless steels). Oxide fumes from titanium are dust hazards (Titanium dioxide is an inhalation carcinogen). Even if a metal is compatible inside the body (like titanium), the fine and irritating nature of these oxide particles can exhibit carcinogenic and other toxic effects when they lodge in the lungs.
Our lungs were designed to handle naturally occurring dusts. These occur due to winds, sand, dust clouds, fur, shedded skin cells etc. Naturally occurring dusts are usually much larger particle sizes than man-made dusts, e.g. combustion (see modern china), and our lungs can adaquately remove low concentrations of naturally occurring dusts. The incredibly fine nature of dusts produced during combusiton, such as PM 10 and PM 2.5 (e.g. smoking, uncontrolled burn-offs and un-scrubbed coal/wood combustion) is one of the reason why smokers have high rates of heart disease.
PM 10 and PM2.5 (microns, or millions of a meter) are so small that they penetrate the alveoli in the lungs, and pass into the blood stream, where they can deposit in arteries in the heart.
Oh yeah, dont use pure nickel coils. Nickel passivating oxides on the surface of the coil will react with any tart flavourings in the juice (green apple, sour flavours, cola flavours etc). This will convert the very stable and mostly harmless nickel oxides into soluble salts. These will dissolve in the e-juice. If you get the juice in your mouth, you will be exposed to nickel salts, which are carcinogenic in high levels.
The problem of nickel poisoning is not significant in stainless steel. Nickel does leach out of stainless steel when cooking acidic tomato sauces, and can reach concentrations of 80ug/L (micrograms per litre). This involves several hours of simmering between 60-100C. Maximum daily recommended intake of nickel sits at 1000ug/day (micrograms per day) for an average person. For comparison, nickel levels in tap water carried by stainless pipes in denmark sit at around 35ug/L.
You would need to drink ~25L of denmark tapwater per day to reach the max nickel exposure limit. You would need to eat ~12L of tomato sauce that had been simmered in a stainless steel pot to reach max nickel exposure limit.
Source: http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf
(pg 348)
Stainless Steel Leaches Nickel and Chromium into Foods During Cooking
Stainless steel leaches nickel and chromium into foods during cooking. - PubMed - NCBI
1ug = 1 millionth of a gram
There is no danger of metal fumes from coils operating at or below 300C
Nickel coils run risk of nickel contamination in e-juice.
Tamman Temperature
This is the crux of my post. Tamman temperature is the lowest temperature at which atoms in a metal (e.g. metal wire) will become significantly mobile, and "evaporate" from the metal. These hot metal particles usually react with oxygen to form oxides.
http://www.che.ncku.edu.tw/facultyweb/leeyl/94 界面現象/Chapter 07 Solid Surface.pdf
The bad news: dry fire your coils with good ventilation. Not in a closed room. Preferably outdoors. Dont huff the fumes.
The good news: The tamman temperature of most metals is about 3/5 of the melting point.
If kanthal melts at 1500 degrees C, then the tamman temperature will be 900C (the metal will be orange/yellow at this temp)
If stainless 316 melts at 1400 degrees C, then the tamman temperature will be 840C (again, orange/yellow hot)
So there is no risk of metal exposure in e-cig vapour at 200-300C for any common coil metal.
This conversion does not work interchangeably from degrees Kelvin to deg. C. Should be ok for Fahrenheit/Celsius.
We've all dry fired our coils to ensure even heating. Im sure many of us have seen fumes rising from the metal once it reaches orange/yellow hot.
If these fumes are coming off the metal before it is glowing hot, it is from oil. This can be machine oil or oil from your hands.
If these fumes are coming off the metal coil when it is glowing, they are not harmless machining oil vapours. They are metal oxide vapours.
Metal oxide vapors from drying firing coils are toxic. Nickel and chrome would be two examples of this (nickel200, nichrome, kanthal and stainless steels). Oxide fumes from titanium are dust hazards (Titanium dioxide is an inhalation carcinogen). Even if a metal is compatible inside the body (like titanium), the fine and irritating nature of these oxide particles can exhibit carcinogenic and other toxic effects when they lodge in the lungs.
Our lungs were designed to handle naturally occurring dusts. These occur due to winds, sand, dust clouds, fur, shedded skin cells etc. Naturally occurring dusts are usually much larger particle sizes than man-made dusts, e.g. combustion (see modern china), and our lungs can adaquately remove low concentrations of naturally occurring dusts. The incredibly fine nature of dusts produced during combusiton, such as PM 10 and PM 2.5 (e.g. smoking, uncontrolled burn-offs and un-scrubbed coal/wood combustion) is one of the reason why smokers have high rates of heart disease.
PM 10 and PM2.5 (microns, or millions of a meter) are so small that they penetrate the alveoli in the lungs, and pass into the blood stream, where they can deposit in arteries in the heart.
Oh yeah, dont use pure nickel coils. Nickel passivating oxides on the surface of the coil will react with any tart flavourings in the juice (green apple, sour flavours, cola flavours etc). This will convert the very stable and mostly harmless nickel oxides into soluble salts. These will dissolve in the e-juice. If you get the juice in your mouth, you will be exposed to nickel salts, which are carcinogenic in high levels.
The problem of nickel poisoning is not significant in stainless steel. Nickel does leach out of stainless steel when cooking acidic tomato sauces, and can reach concentrations of 80ug/L (micrograms per litre). This involves several hours of simmering between 60-100C. Maximum daily recommended intake of nickel sits at 1000ug/day (micrograms per day) for an average person. For comparison, nickel levels in tap water carried by stainless pipes in denmark sit at around 35ug/L.
You would need to drink ~25L of denmark tapwater per day to reach the max nickel exposure limit. You would need to eat ~12L of tomato sauce that had been simmered in a stainless steel pot to reach max nickel exposure limit.
Source: http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf
(pg 348)
Stainless Steel Leaches Nickel and Chromium into Foods During Cooking
Stainless steel leaches nickel and chromium into foods during cooking. - PubMed - NCBI
1ug = 1 millionth of a gram
Last edited:
