Burning Saw Milled Lumber

[Todd]

I think this subject was brought up a while back, but I was reading this from the chimney Sweep Online Site. (broken link removed)

What do you guys think of this? I called Woodstock and they said it's a no no. Over time the chemicals in milled wood can clog a catalyst. Oops, I've been burning saw mill lumber for a month now! What about bar oil from a chainsaw? They must put more lube on sawmill saws? Or is this all just a bunch of hoopla?

 

[Shane]

What he says makes some sense. I haven't personally experienced such a thing though. We recently hooked up a parlor wood stove in the shop. I've been disposing of palets in it. In a year I'll let you guys know what shape the chimney and stove are in. Stuff does burn fast and hot but not uncontrollably.

 

[Turner-n-Burner]

Reading that had just about scared me away from burning lumber scraps!

But then I remembered what wood pellets are made of - from www.pellet.org "Pellet fuel is made mainly of sawdust, shavings and fines leftover after processing trees for lumber and other wood products"

So wood pellets would be contaminated inside and out? Like bad hamburger right? You'd have to expect them to have a much higher concentration of contaminates than hardwood scraps would... So are pellet stove owners having corrosion issues galore?

And what about coal? Coal has a pretty high sulfur content... Do coal stove chimneys rust out quickly?

I guess I could buy the salt issue, maybe that's a regional thing? Don't think they're using log booms around here too much.

Love to hear an expert chime in on this one.

-Dan

 

[Shane]

That's a great point and makes perfect sense.

 

[minesmoria]

I live on the bc coast next to alaska, some of the wood i get comes from the log sorts and has been in the ocean for a while than on land.


One guy said hes been burning salt wood for 7 years and has no damge to the stove.

Most of the time the flames are regular color no bright yellow or blue flames which salt gives off.

 

[babalu87]

Christ, they make it seem like you can only burn old growth forest planted by the Virgin Mary

Anyone want to buy a woodstove, I ascared to fire mine now

 

[Todd]

What about bar oil from a chainsaw? I guess we'll all have to start processing wood with hand saws!

 

[Sandor]

I don't get this.

What chemicals in milled wood? Years ago, I bought a load a rough sawn hardwood cutt-offs from the mill and it was great. A friend of mine has a sawmill and I get cut-offs from him.... I say hoopla, and burn away.

I don't think were talking about burning treated wood here.

I think there is little chainsaw bar oil left on the wood worth mentioning. The dust on the ground is another story, but thats why I use vegatable oil, and that topic has already been covered!

 

[elkimmeg]

This topic surfaces from time to time I have been burning 30 years two stoves and now I find out I should not burn construction grade lumber. I did not notice any signs of drterioation in my 25 year original stove. Dose anyone know what to look for, concerning construction grade wood burning deterioation? If you cannot answer that question, then why is it bad to use? during the lumber processing some cutters blades planers and sawing use lubricants. This is true, but the smallest amount of traces might be found in it If were saturated you could not paint it. Paint would not adhere to it. So all those clear pine and oak pieces, just got from the stairs I remodeled,I can't burn? If you believe this. Here is another one Bush pulled all troups out of Iraqu today Santa Clause is not real?

 

[Eric Johnson]

I think that's a lot of sensationalistic and ill-informed hoo-ha. Most of the sawmills I'm familiar with cut logs in the woods, truck them to the mill, store them for as short a time as possible, then cut them into lumber, dry it and ship it. About the only chemical some mills use around here is a little wax on the ends to keep the logs and lumber from checking. A little kerosene on the blade (which ain't all that common, especially if your saw filer knows what he's doing) is not going to cause a problem, mainly because it's going to evaporate in the kiln or out in the sun in the yard. There are better ways to avoid sticker stain than using oxalyic acid. I've never heard of that being used here in the Northeast. It's illegal to float logs in a waterway--has been since the '70s in the Northeast. I don't know about the ocean, but that's only going to be softwood from the west coast, if it's an issue there (which I doubt--the proceedure there is pretty similar to what I describe above, from what I've seen.

The only thing I've ever seen applied to logs, in addition to the wax mentioned above, is plain water, which is sprayed on to avoid checking and staining.

Finally, most sawmills burn some or all of their residue, so I think if residual chemicals were a problem, they would be the first ones to be concerned.

 

[thechimneysweep]

Even wood straight from the tree contains natural aldehydes and other substances that become corrosive as a result of the combustion process. I think most woodburners who have been at the game for any length of time have had to replace "burned out" stovepipe sections, baffle plates, or other internal stove components a time or two. We don't think those parts are burned out from the heat of the fire so much as corroded away from exposure to the products of wood combustion. Back in the '70s, when we started our chimney cleaning business, we learned that the creosote we swept out of people's chimneys would eat right through our galvanized steel containers and even the beds of our trucks in time, if we weren't careful to contain it in plastic.

The point of the article in our online Sweep's Library cited above is that mill ends contain those natural corrosives, plus any additional chemicals that might be introduced during the cutting, transport, kilning and milling processes.

There are lots of lumber mills here in the Pacific Northwest, and an abundance of inexpensive mill ends to burn. Many people around here burn mill ends exclusively, and have been doing so for decades with no noticeable ill effects to their stoves or chimneys. But things have changed, both in the sawmill industry and the woodstove industry. We first noticed the accelerated corrosion phenomenon in the '80s, when stoves incorporating the then-new non-catalytic secondary burn technology first hit the marketplace. We were the first to specialize in the non-catalytic "clean air" stoves in our area, and we soon realized that it was those stoves that exhibited the problem. But the problem was far from universal: some of our customers who replaced their old stoves with those models were going through stovepipe and baffle plates at a tremendously greater rate than their neighbors who had purchased the same models.

We weren't quite sure what the cause might be for the increased number of customer complaints about premature component failure relating to the new-technology stoves, but the great majority of our clean air stove customers weren't having this problem, so we looked for a common denominator. That's how we came across the mill end correlation: when faced with a stove exhibiting internal shaling or holes in the baffle system, we would tell our Sweeps to ask the customers what they were burning. And almost all of them were burning mill ends. Even people who had been burning mill ends for decades in their old FIshers and Shraders with no remarkable ill effects began to experience stovepipe and baffle failure while burning the same fuel in their new stoves. We developed the theory that the super-hot internal temperatures created inside these high-tech models seemed to accelerate the corrosion process when mill ends were burned.

As to exactly why mill ends cause this problem, we just don't know. The article in our online Sweep's Library cited above was an answer to a site visitor's question, and was meant to point out some of the chemicals even "untreated" mill ends might contain. We didn't mean to imply that all mill ends are soaked with saltwater or PEG-1000 or fungicides or oxalic acid, we just wanted to point out the fact that some certainly are, and to share our opinion that this extra chemical content might be related to the accelerated corrosion we have observed.

 

[Eric Johnson]

Well, I apologize for suggesting that the link was "ill-informed." Obviously that's not the case.

It's an interesting theory. I'm going to be talking to some sawmillers over the next couple of days, and I'll ask what, if anything, they put on their logs and lumber. My experience is limited to the Northeast, but I'm betting they'll say "nada."

 

[Sandor]

Paralysis by Analysis.

Burn the freaking stuff and be happy. What a load of crap.

So what if you burn out a $20 section of pipe every 10 years.

Eric, your a Saint.

Got my Dylan hat on!

 

[Todd]

I'm not so worried about the pipe, more worried about coating the honey comb of a catalyst with those extra chemicals? Would it cause premature failure? Or is the stuff evaporated before engaging the cat?

 

[Sandor]

I'm not so worried about the pipe, more worried about coating the honey comb of a catalyst with those extra chemicals? Would it cause premature failure? Or is the stuff evaporated before engaging the cat?

What extra chemicals?

The only time I saw wax being applied to the finished product was to Ipe or Redwood.

The cutoff stuff you get from the mills is usually from the first cut. Like when it was dragged from woods. The wax is applied to the finished cut on valuable wood.

 

[thechimneysweep]

Sandor, we're not talking about eating through a piece of stovepipe every generation here. We're talking about big holes in steel baffle plates after only two or three years. And we're not talking about an isolated incident: we have seen dozens of cases over the years. One of our customers actually had to replace his 1/4" steel Pacific Energy secondary burn chamber twice in five years. PE replaced the first one under warranty, but denied the second claim, so he had to pay for that one himself. He finally listened up about the "untreated" mill ends he was burning, stopped burning them, and hasn't corroded through the third baffle in the ten years since.

We're also not talking about burning log butts. The question and answer in our Sweep's Library are about dimensional lumber: lumber that has been through the mill. When you respond to an ad for mill end fuel around here, you get a truckload of trim-offs: these are short chunks of random-length kiln dried 2x4's and such, not the sawed-off butt of a tree.

Finally, we're not making these chemicals up. If you'll click the links at the bottom of the page, you'll see that the chemicals referred to are not imaginary: they're in common use and gaining in popularity, especially in plants that practice modern "dry kilning".

 

[minesmoria]

Tom,

what about his chimney did it have holes like the baffle plate did or was it okay was it stainless or brick chimney?

I would think the baffle would get the most damage, as this is wear the heat is not the chimney so much.

 

[berlin]

I don't personally believe that chemicals have anything to do with baffles burning out, it is not corrosion, it seems far more plausable that they way in which this dried small pieces of wood burn is accelerating burn out in parts of these stoves, perhaps they release thier volitiles quicker thus heating certain parts of the stove faster than it would be heated with reletively moist cordwood.

 

[Sandor]

I don't personally believe that chemicals have anything to do with baffles burning out, it is not corrosion, it seems far more plausable that they way in which this dried small pieces of wood burn is accelerating burn out in parts of these stoves, perhaps they release thier volitiles quicker thus heating certain parts of the stove faster than it would be heated with reletively moist cordwood.

Berlin, I agree. I would guess the stove was over-fired.

The sawmill stuff I am talking about is the scrap generated when the logs are rough cut, before they hit the kiln.

 

[Mo Heat]

I personally have no idea one way or the other, but to me, Tom Oyen has the better argument with better supporting data. And he likely has as much or more experience with both this phenomenon and non-cat technology and installations than most of us.

The fact that discontinued use of a particular supply of dimensional lumber (maybe not the stuff in other parts of the country) resulted in a correction of the problem seems a strong indicator of root cause to me. But again, I'm only judging the arguments presented and have no specific knowledge of these chemicals, non-cat technology, dimensional lumber, burned out baffles, burned out chimneys, or much of anything else for that matter. Not sure why I'm even posting except it seems like Tom could use at least one person in his camp.

 

[berlin]

MO, i think that perhaps you mistook what i have said. I am not dismissing toms experience and knowlege alltogether. I believer that it is possible that stoves could burn out baffles and other parts faster burning this lumber, however, i do not for a minuite believe that chemicals are responsible for the problem, rather it is another aspect of the particular fuel's characteristics that might be accelerating burnout of certain parts of the stoves. I have some experience with powerplants diagnosing corrosion problems linked to high clorine + high sulfur coal combustion; and i can say with some confidence that i don't believe that sawmill ends are "corroding" through 1/4" plate steel in a domestic wood stove.

 

[Mo Heat]

MO, i think that perhaps you mistook what i have said. I am not dismissing toms experience and knowlege alltogether. I believer that it is possible that stoves could burn out baffles and other parts faster burning this lumber, however, i do not for a minuite believe that chemicals are responsible for the problem, rather it is another aspect of the particular fuel's characteristics that might be accelerating burnout of certain parts of the stoves. I have some experience with powerplants diagnosing corrosion problems linked to high clorine + high sulfur coal combustion; and i can say with some confidence that i don't believe that sawmill ends are "corroding" through 1/4" plate steel in a domestic wood stove.

I see. Your argument also seems plausible.

I guess the important thing for those folks whose baffles and pipes were burning out is that they found how to stop it.

On the other hand, it would be good for others who are burning diminsional lumber to understand exactly what component(s) or characteristic(s) of, or in, the diminsional lumber were involved in the examples Tom gave for prematurely burned-out parts and to determine if the diminsional lumber they are burning possesses that characteristic or component. I suppose that's the rub.

Failing that identification, it seems logical to either stop burning diminsional lumber or to keep a close eye out for burned-out parts, which may or may not occur.

 

[Eric Johnson]

I talked with a few big hardwood sawmillers at a meeting in New Hampshire this morning, as well as the NH Extension Sawmill Specialist and they all said that nobody puts anything on logs and lumber in this part of the world, except the aforementioned plain water and wax.

I do know that the tannic acid from hardwoods, especially red oak, will corrode a dry kiln over time. Never heard of red oak burning out a baffle or stove pipe, however.

I know some people in the sawmill business in Washington State and Oregon. I'll see what they have to say when I get the chance.

I'm not trying to give Tom a hard time, but the forest products industry has a sorry enough public image as it is, without people getting the false impression that sawn lumber is laden with dangerous and/or corrosive chemicals. As I said, I only know about the industry in the Northeast, but you don't have to worry about burning mill residue and pieces of lumber produced in this region.

 

[Sandor]

Nice work debunking the myth, Eric.