Smoke Color

[MrBirdman]

I’m wondering if anyone else has noticed a difference in smoke color from an “idle” cigar that’s letting off smoke, and the smoke that results from actually puffing. I only just realized that the former is a steely-bluish whereas the latter is more yellow. I’ve tried to capture this but smoke is tough to get on camera. 

I presume it’s the result of increased combustion heat. Anyone else notice and/or have alternative theories?

[Zaxeiler]

I noticed that this week too (although I would have said he puffed smoke is more white). More data for this mystery - as it has gotten darker for the winter, I’m on the back deck under LED flood lights. Wonder if that has something to do with it, never noticed it under natural sunlight. 

[MrBirdman]

8 minutes ago, Zaxeiler said:

I would have said he puffed smoke is more white

Agreed, it’s definitely whiter just with a yellowish tinge. The idle smoke is more a bluish grey than a white. 

[Hammer Smokin']

maybe it's the colour of smoke mixed with oxygen vs the colour of smoke mixed with carbon dioxide? 

[MrBirdman]

1 minute ago, Hammer Smokin' said:

maybe it's the colour of smoke mixed with oxygen vs the colour of smoke mixed with carbon dioxide? 

I wondered whether it was that or (more worryingly) a result of something being "left behind" in my mouth (like tar). Fortunately from my observations the smoke produced by purging - which would be the same as from puffing but which hasn't gone into the mouth - is the same color as the white-yellowy "puffing" smoke described above. That's why I suspect it's the result of different combustion temperatures (idle being the cooler of the two). The flavor changes from over-puffing must be due to different combustion products - so it would make sense that there are differences in the smoke. I just hadn't considered/expected that it would extend to the color of the smoke.

Funny thing is I've heard people reference smoke (usually from cigarettes) as blueish and never understood it. Now I realize they probably meant the wisps from the lit end, not what people exhale. 

[rcarlson]

I'd wager that the smoke changes color because the size of the smoke particles changes. The smoke particles rising from the foot are very small, smaller than the wavelengths of visible light.  Because the particles are so tiny, when most light waves strike one of them they are not reflected back like a bouncing ball, but only slightly deflected from their paths.

Oh, what do you know. . .   https://indianapublicmedia.org/amomentofscience/why-cigarette-smoke-is-blue-or-white.php#:~:text=The smoke changes color because,the wavelengths of visible light.

[MrBirdman]

Great find @rcarlson! That helps explain how the difference in color actually operates - now the question remains what causes the difference in particle sizes.

As I mentioned above the smoke is white from purging too, so unlike with cigarettes it can’t be because it’s entering the body (which was my initial concern). The most obvious possible explanations would be either that the increased combustion temp of puffing, or the increased airflow, increases the particle size of the resulting smoke. 

[rcarlson]

21 minutes ago, MrBirdman said:

Great find @rcarlson! That helps explain how the difference in color actually operates - now the question remains what causes the difference in particle sizes.

As I mentioned above the smoke is white from purging too, so unlike with cigarettes it can’t be because it’s entering the body (which was my initial concern). The most obvious possible explanations would be either that the increased combustion temp of puffing, or the increased airflow, increases the particle size of the resulting smoke. 

I think the piece I linked to explains it to some extent:

  "Many are exhaled, though, and when they come out they have changed again. While in the lungs, and on the way out, they pick up moisture so they become bigger still."

I would think the same principle would apply to a stogie (i.e. picking up moisture in the mouth and also along the length of the cigar, which also hold moisture).   

[MrBirdman]

6 minutes ago, rcarlson said:

I would think the same principle would apply to a stogie (i.e. picking up moisture in the mouth and also along the length of the cigar, which also hold moisture

I suspect that that’s it, and also the trip through the filler itself could cause particles to flocculate more and get bigger. I would be interested in whether there was a noticeable difference in color with either RH in storage or the smoking environment. 

I have noticed some of the gigantors with huge smoke production make a whiter looking smoke, though that may just be due to the increased density.