Soot Mystery: Uncovering the Puzzling Phenomenon in a Wood-Burning Stove Room

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The discussion centers on the puzzling phenomenon of soot accumulation on walls and ceilings near studs in a wood-burning stove room. Participants suggest that the thermal properties of the studs may create colder spots, leading to increased condensation of moisture and soot. There are also considerations about the potential for chemical reactions or humidity affecting the discoloration patterns. Some participants propose that the soot may not be soot at all but could be related to other factors like joint fillers or moisture issues. Overall, the consensus leans towards thermal dynamics and moisture interaction as key factors in this soot mystery.
  • #31
DaveC426913 said:
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OmCheeto said:
Is this in Toronto? I see that you have 3 months of sub-freezing weather during the year. This might be a clue.
Yes, but how?

Like I said, I've been using my wood stove for 20 years and have never seen such a thing. It's been at least 15 years since I've painted, and there is absolutely no indication of such marks on my peripheral walls.

Comparing temperatures of a few of the responders:

pf.ave.monthly.temps.jpg


It's obvious that you've got the highest temperature gradient in the winter. And if that really is just an enclosed porch who's only heat source is the wood stove, the studs are going to be ice cubes if the fire goes out. And as SophieC stated, their heat capacity is going to cause them to take a lot longer to warm up.

I see two outstanding questions:
1] Are the studs going to be warmer than the air or vice versa? Or is there a more complex reaction occurring over time?
2] How does thermal change result in changes in soot accumulation?

I'm going to go out on a limb and state that I'm 99% positive that the walls and ceilings are insulated, and the soot is a result of studs being the cold spot.

Borek's January temperatures, and observations regarding the screws, seem to support the hypothesis.

I would make a joke about the studs sucking the thermal energy from the room like a vacuum cleaner, and carrying the soot along with it, but that would be silly.
 
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  • #32
OmCheeto said:
It's obvious that you've got the highest temperature gradient in the winter.
To be clear, I was not doubting the temp gradient. I am well aware of it; I just was having trouble connecting the dots about how that lead to the observed phenom.


I think the biggest difficulty I've been having is that I've been intuitively assuming that it would be warmer under the studs than elsewhere. But if it's actually colder under the studs - especially during the initial fire-starting phase when soot emission is highest - then the rest makes sense.

Thanks guys.
 
  • #33
I still wonder whether what you are seeing is actually just 'soot'. I think it's more likely to include tar (sticky) - like you get with cigarette smoke.

Next time you go round, you need to offer to clean their ceiling and walls and see whether you need detergent to shift the marks.
 
  • #34
Ok, the stove is only lit in cold weather. I am assuming that the porch room does not have a connection to the household heating system. Assuming these, I feel safe saying that the studs, drywall, air behind the walls, furniture ect... Have all reached thermal equalibrium as a system. Lighting a fire rapidly heats the room air. That heat is then transferred to all the surrounding matter through the usually channels. All the materials that are in contact with the air are going to warm at different rates. The studs are connected to another wall, the outside one. If the air temp outside is cold enough, I'd think under 50f, then the studs simply take longer to warm. Wood is a great insulator, but it also contains water and retains the ability to absorb it even in the afterlife. This could skew the woods heat capacity. The wooden studs absorb the heat that the drywall (at the point of contact) is absorbing. Depending on the conditions, it is plausible that the studs could take a significant amount of time to heat, and until they reach equalibrium they will continue to act like moisture magnets.
 
  • #35
Does the wall facing the house suffer the same soot lines? I am assuming the outside wall of the house that the porch is attached to in the porch room was not significantly reconstructed when the room was converted. I wouldnt. This means that the porch room is probably insulated from the rest of the home but those studs (likely connected to an inside wall) would not be subject to soot accumalation.
 
  • #36
TEjedi said:
Ok, the stove is only lit in cold weather. I am assuming that the porch room does not have a connection to the household heating system. Assuming these, I feel safe saying that the studs, drywall, air behind the walls, furniture ect... Have all reached thermal equalibrium as a system. Lighting a fire rapidly heats the room air. That heat is then transferred to all the surrounding matter through the usually channels. All the materials that are in contact with the air are going to warm at different rates. The studs are connected to another wall, the outside one. If the air temp outside is cold enough, I'd think under 50f, then the studs simply take longer to warm. Wood is a great insulator, but it also contains water and retains the ability to absorb it even in the afterlife. This could skew the woods heat capacity. The wooden studs absorb the heat that the drywall (at the point of contact) is absorbing. Depending on the conditions, it is plausible that the studs could take a significant amount of time to heat, and until they reach equalibrium they will continue to act like moisture magnets.

Deja vue. See Post 6 etc..
 
  • #37
sophiecentaur said:
I still wonder whether what you are seeing is actually just 'soot'. I think it's more likely to include tar (sticky) - like you get with cigarette smoke.
Well, I didn't think it made a diff, but ... while not "smokers", they are ... very "frequent flyers".
 
  • #38
sophiecentaur said:
Deja vue. See Post 6 etc..

Sorry Sophie, I was just trying to expand on your intial thoughts with a few additional factors that may better explain the process and still keep it comprehensible. I am still new to the forum and don't quite have a mastery of its general features, like the quote button I plainly see today but somehow missed last night, and apologize for not attributing it to you first.
 
  • #39
TEjedi said:
Sorry Sophie, I was just trying to expand on your intial thoughts with a few additional factors that may better explain the process and still keep it comprehensible. I am still new to the forum and don't quite have a mastery of its general features, like the quote button I plainly see today but somehow missed last night, and apologize for not attributing it to you first.

No worries. I'm not at all offended. Only it's very common for people to read the most recent posts of a long thread and to repeat contributions from earlier on (dunnit myself too often).