Kiln Drying Questions for the Experts.

[slohand]

We are considering putting in a small kiln this summer, likely a Nyle L200 and have a couple of questions regarding operation procedures to get the best quality dry lumber output with minimum drying defects.

We have all kinds of custom kiln capacity within 5 miles of our mill, several different operations. For years whenever we needed flooring or mouldings stock done we'd truck down there and have it back a week or so later. It cost around $200-$220 per thousand.

Now though, it seems the price is going up and the quality down. I'm getting real tired of getting back a bunch of lumber where every knot seems to be a star knot or loose or gone completely.

The basic problem is that a custom drying services has a different objective than I do. They just want to get the stuff through quick so they can get paid. So my lumber is just getting the h... cooked out it.

We will be drying primarily Douglas Fir which, I think, would be more like Pine. Most of the forum topics on drying seem to relate to Eastern Oaks and other hardwoods which are quite a different project I'm sure.

Anyway I've heard that the trick with drying resinous woods like Fir or Pine is to have a pre cycle phase that essentially raises the internal temp of the boards before beginning to actually run the de-humidifiers and fans.  One way (apparently)
is to run the kiln up to a high temperature with no fans and the dehumidifiers off for about a day.
The other method is to do the same high temperature cycle but add water or mist or steam while doing it to prevent the outside of the board from drying out as the inside warms up.

Either way the temperature goes up to around 160 degrees... for about a day I think.

After this pre cycle you run the kiln normally to dry the wood out.

But, my thinking, for best quality results it would still be better to run it  not too hot. Maybe 80-90 degrees.

Anybody have experience/opinions with this type of wood and how to get best drying results. And have they tried either of the above two pre cycle methods and if so for how long.

[Coon]

Do you plan on air-drying the pine down somewhat before putting into the kiln? 

[red oaks lumber]

i would'nt even think of not having your fans running, you'll have mold ,blue stain ect. kilns have 3 basic functions.
1) heat releases the water from the wood
2) the fans remove the water from the layers of wood
3) condenser turns the moister to liquid for removal
to best control how fast or slow you dry your wood.  is slowly increase the kiln temp. and set your compresor cycle to run less oftn.  the best way find a good kiln drying schedule and start with that.
when i dry pine i go as hard and fast as possible. my thoughts on d.fir would be dry it fairly aggresive only close to the end run the temp up to set the pitch ect. but the only d.fir iv'e dried has been reclaimed not green.
good luck

[scsmith42]

i would'nt even think of not having your fans running, you'll have mold ,blue stain ect. kilns have 3 basic functions.
1) heat releases the water from the wood
2) the fans remove the water from the layers of wood
3) condenser turns the moister to liquid for removal
to best control how fast or slow you dry your wood.  is slowly increase the kiln temp. and set your compresor cycle to run less oftn.  the best way find a good kiln drying schedule and start with that.
when i dry pine i go as hard and fast as possible. my thoughts on d.fir would be dry it fairly aggresive only close to the end run the temp up to set the pitch ect. but the only d.fir iv'e dried has been reclaimed not green.
good luck

+1, although at 160F you probably won't have much mold growth, even w/o the fans!. 

I operate a version of the Nyle L200.  For SYP, it's good for about 1500 bd ft and requires about 2 weeks.  For oak, about 4000 (slower drying rate).  Typically with pine you run up to 160F at the end of the cycle to set the pitch, not at the beginning.

If you're going to be drying any volume, you might want to consider either a larger unit or using multiple L200's on the same kiln.