2 questions about air drying lumber

[fluidpowerpro]

2 questions I've been meaning to ask for a while now.

1.So far every thing I have cut for myself obviously is stacked and stickered for drying, and it has stayed that way until I have used it. Is there a point in time where it can be stacked without stickers? I do have a low buck moisture meter that I can measure with so is there a certain %? It would be really nice to at some point be able to stack it without stickers for long term storage.

2. Often times for dimensional lumber I'm cutting Red Pine and in almost every case it molds while drying. The last time I cut I made sure to get the stack higher off of the ground and used bigger stickers. I also made sure there was a gap between every board with the intent of increasing air flow. I have yet to see how that turns out, but I expect to still see some mold.

A. When I have used some of this lumber even though I dont think the mold is a issue ( always for outside sheds, etc) I have sprayed it with a mild solution of bleach and water and the mold and staining goes away. Is the bleach bad for it?

B. I have often wondered if as I am stacking, if I sprayed it with a mild bleach solution, if that would help prevent mold.

Any feedback will be appreciated.

Also, as far as mold, my experience has been that it seems to only be an issue with softwoods (Red Pine, Tamarak, Fir, Poplar). I also cut a lot of Red Oak, Birch and some Maple, and never had an issue with mold on that. Is that experience what I should expect?
I wonder why it seems softwood is more susceptible to molding?

I guess now its 6 questions.

Thanks,
Tom

[ladylake]

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 Where are you drying it, how wide are the stacks.  Steve

[fluidpowerpro]

Typically 4-5 ft. Probably too wide??

[btulloh]

Fans on pine in warm weather. Shade cloth on oak. Pine needs to sped up when freshly sawed. Oak needs to be slowed down to avoid drying too fast and getting surface checking. 

[Don P]

Narrower will lower the humidity in and around the pile.

Most fungi need free moisture to water the mold itself. Below fiber saturation point throughout the wood means the moisture remaining is "bound" to the cell wall. That varies but is around 25%. Construction lumber at 19% is considered safe to dead stack and transport. If you get moisture on the wood or in the pile you will have problems. I prefer to keep it on sticks for that reason but it does take twice the room.

Cut in winter and it'll be below FSP by the time it warms up enough for mold to grow. Lots of airflow is key, fans when its warm. Technically clorox pulps the wood, doesn't kill all the spores down in there or prevent the next infection and it introduces moisture. Not saying I haven't done it. There are specific products to prevent stain but I've tried to stick with sawing pine in the cold and airflow.

[boonesyard]

Yes, pine will mold overnight if there's no air movement. This is a load of 8/4x10" red pine we cut last week that's stacked in a covered, open shed but still not enough air movement. We put a barn fan on it right away and run it for week. Just tested it for moisture and it was down around 25-30%, no longer a mold threat nor need for fans. Ready for the kiln 

[Wlmedley]

Glad you asked these questions.I have been wondering the same things.I have 300 board feet of pitch pine air drying in shed on stickers.Haven't saw any mold.Hopefully not molding in lower part of stack.Guy has already paid me for it.It's been there at least a month.

[fluidpowerpro]

Technically clorox pulps the wood, 

Sorry... what does "pulps" mean?

[Don P]

Disintegrates the bonds between fibers creating papermaking pulp. The sun and weather does the same thing. It's neat to watch a wasp gathering fibers from weathered siding to make their gray paper nest. Will it turn the wood to mush, no, will it help the wood, no.

[terrifictimbersllc]

Pretty sure there's no issue dead stacking air dried lumber, so long as it can't get wet. So you wouldn't just take the stickers out of a outdoor sticker pile and leave it covered on the top sides open. It would have to be protected from any water that could get between the boards. Otherwise you'd have fungus sticking the boards together, and in some species like cherry, ants moving into their new hotel.

[Ianab]

I wonder why it seems softwood is more susceptible to molding?

It's not so much about hard / soft wood, it's about the natural chemicals in the wood. Naturally durable woods like cedar / white oak / walnut are loaded with assorted chemical goodness that discourage insects and fungus from feeding on it. Cedar is a softwood (very soft), but loaded with natural chemical preservatives.  But less durable woods like pine or maple are a nice sugary feast for bugs / fungus etc. Those have to be dried faster, before something starts "eating" or staining them. 


Same goes for sapwood / heartwood. The whiter sapwood of even durable species like red cedar / walnut isn't very durable as it's still "live" wood (carrying water and nutrients for the tree) The darker heartwood has been loaded up with the chemicals that make the wood durable. 

[OlJarhead]

great answers!  Ir movement is crucial in drying lu.ber and preventing mold.  I dry all mine in the open and never have mold

[fluidpowerpro]

Mine is under roof. Basically a 26 x 32 x 10' high shed with no walls.

[Ianab]

Mine is under roof. Basically a 26 x 32 x 10' high shed with no walls.

What's critical with dead stacked lumber is that water can't get into the stack. If rain blows into a stickered stack it will dry out again next day and not do any harm. but if it trickles down into a dead stack, water could sit in there for weeks, and stuff starts growing.  :-\

[fluidpowerpro]

That's where I dry it with stickers. I have not dead stacked any so far. Im getting mold so I don't have adequate air flow. There is no electricity in that shed, so can't do fans. As suggested by Don P,  I think the answer will be to saw pine when it's colder out. This time of year in MN its hot and humid so ideal for mold.

[Ianab]

Yeah, depends on your local climate. Here in NZ pine is best air dried in summer because it's warm enough to dry quickly, as long as it's in a breezy spot. Winter here isn't cold enough to stop mould / fungus, it's just cool and humid, so the fungus just grows slower while the wood hardly dries. But in a colder / drier climate you are correct, and wood will dry slower but safer. When the weather warms up the wood is then dry enough that you don't have to worry any more. 

That's where the old wisdom of sawing when the "sap is down" is actually true. Nothing to do with the sap, but stacking the wood to start drying in winter can make a difference in the end results. Less stain in the pine, less checking in the oak (because it's dried slower).   The explanation why wasn't correct, but the old timers wisdom got the best results. 

[WDH]

Two issues are drying rate and stack width.  Pine dries fast so a lot of water is evaporating per unit time compared to hardwoods like oak and walnut.  This creates moist humid air in the air spaces created by the stickers.  For fast drying woods and poor/no air flow, this moist air moves out slowly and creates the perfect environment for mold and mildew, and enzymatic gray stains (like in some hardwoods like maple).  Fans create air flow that moves the super humid moist air out of the stack.  This increases the drying rate and eliminates the conditions favorable to mold, mildew, and gray stain.

Stack widths over 4 feet wide compound the problem significantly.  The super humid moist air has further to go to be removed and coupled with low/no air flow, that is the perfect recipe for mold, mildew and stain.  This problem can be minimized several ways.  Increase air flow with fans or air drying location.  Reduce stack width to facilitate the water vapor getting removed from between the layers, and use thicker stickers to create more between layer air volume to help with water vapor removal.  Cutting and stacking in winter will help, but if you do the other stuff wrong, you will still get problems.  Sticker stain is one of the worst and can ruin high value lumber quickly if you do not mange these variables well.

The sawing is the easy fun part.  Doing the drying right and flat with no stain, mold, or mildew is where the real skill comes in .  You have to set yourself up right to do the drying right, so like Customsawyer says, "You have to pay to play".  There ain't no free ride when it comes to lumber done properly. 

[Nebraska]

When  I saw this time of year I got started just spraying  most everything with solubor before stacking and air drying. It seems to hold the mold down. My temps are warmer but the humidity is as bad as Minnesota.

[jpassardi]

I can't speak for red pine but my experience with white pine is if it's been logged when dormant in winter (lass sap) it can sit as a log for quite a while without blue molding. I have stacked/stickered it up to 8' wide without mold but that was not in the dog days of summer.
One advantage of "dead stacking" after air drying is that it prevents mice from getting in and nesting. They like to nest, crap, pee and chew the middle of my best boards...

[fluidpowerpro]

Yea, I think those mice are at my place too. Ive heard of junkyard dogs. I will look into sawmill cats.

[WDH]

It is not so much less sap in the winter as it is the lower temps where mold and mildew will not grow.  The moisture content in a tree stays relatively constant all year long as it is a living organism.  A human's moisture content does not go down in the winter either.