From you Linked article...
Why is a dry-burn dangerous?
A dry-burn is dangerous for 3 reasons:
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.
- 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.
- The particulate matter can cause allergies. Nickel, for example, is recognized for causing skin rash, itching, redness. Ni is also a carcinogenic compound when combined to carbon monoxide (CO), a product of incomplete carbohydrate combustion. Hence, this type of toxicity is probably less relevant in the case of e-cigarettes than for combustible tobacco products.
- 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.
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1: Metal Oxides form Very Strong Bonds at the Surface Boundary of an Metal Alloy. These Bonds are Not easily broken as anyone who has Polished a Metal to make it shine knows. I haven't seen any Credible studies that have shown that Oxides are migrating either Physically or thru a Chemical Redox in e-liquids/Vapor.
2: Yes. Metal Particulates can cause Allergic Reactions. And in Extreme Cases, while High Levels of Exposures, some Very Significant Health Risks. But once again, these Particulates would need to travel form the Coil into the Vapor Stream.
3: Welders and or Metal Workers can be at Significant Risk to Particulate Exposure. Because they often work in an Environment where Metals are routinely Ground causing Airborne Particles. The Same can not be said for a Vaper. Also, Welders are at a Higher Risk because they can Inhale Fumes coming off Molten Metals.
All Metal Alloys will experience Accelerated Corrosion when they are Heated. But the Amount of acceleration is Directly Proportional to how long a Metal is Heated. That is why a Toaster one day breaks. Or a Light Bulb burns out.
But these Time Scales seem somewhat Disproportional to how long an average Vaper will use a Coil. And for how long a Coil is kept at an Elevated Temperature via Dry Burning.
Whether or Not to Dry Burn is something that a Vaper needs to decide Him/Herself. But I think that the Causality of some Known Risks has, at best, been be wrongly applied to what we do and they way we do a Dry Burn. And at Worst, fueled FUD.
One Last Thing.
If a Person is Dry Burning to Clean the Coil, or to Check for "Hot Spots" or "Hot Legs" there Isn't really a lot of need to Heat the Coil past the point of being able to see a Faint Red Glow at the Center of the Coil.
Once no Smoke is coming off a Coil, it is as Clean as it ever is going to be. And once you can see that the Center of a Coil is starting to turn Light Red, you are pretty much Good to go.
I would also suggest Dry Burning at a Low Wattage like 10 ~ 15 Watts.
Doing This is Extreme Overkill IMO.
