Drying Lodgepole Pine in Colorado
Detailed advice on air-drying and kiln-drying lodgepole pine (some logged green and some killed by beetles). April 21, 2008
Question
I think I've read every post on drying by now and downloaded several publications. I've also contacted the CSU Extension office and spoken to two local sawmills/drying yards. I have gotten a wide variety of opinions.
I have some green as well as some beetle-kill (semi-dry on the stump) lodgepole pine. I would dry these in separate charges. It has been milled to 1x8 to 1x12 size (rough). I would like to know if I can sticker (and weight) it in my woodshop in a stack that is 4'x4'x12'. I would use stickers that are 3/4" x 1 1/2" at 18" spacing. The shop is heated (forced air) and maintains approximately 25-30% humidity. Shop is 20'x30'x16' h. I could coat the ends and run a window fan or two through the stack. The temperature runs approximately 70 degrees in the daytime (due to solar) and I keep it about 50 degrees at night. I can adjust this as well if desired.
I considered a solar kiln (for speed, setting pitch, etc.) but I was told by the county extension office my drying times would be fairly rapid due to Colorado's dry air. Therefore, I might only gain a short amount of time by solar kiln drying. A local mill told me a lot of the standing beetle-kill was pretty much dry. They said it would easily air dry in two weeks.
Essentially, I'm looking at protected air-drying on steroids. I can open up the shop and move a lot of air if necessary. I figure the addition of the fans would speed the process.
Forum Responses
(Sawing and Drying Forum)
From contributor D:
It will work, but your building will probably rot away pretty fast.
From Professor Gene Wengert, forum technical advisor:
Each 1000 BF will have about 1200 pints or 150 gallons of water that must be evaporated. Would you be willing to evaporate that much water in your shop and run the risk of high RH and corrosion or decay? You are using your shop as a kiln and that is just not a good idea. I do like a kiln that is heated to kill the insects and also set the pitch. Why not use an open shed and air dry to low MCs? Then a day at higher temperatures will make a great product.
From contributor W:
Standing dead lodgepole (1 year) will have a core MC of 18-26% when sawn in the summer. So it isn't something you want to dry in your shop. Air dry outside with good air flow and finish in the shop when dried to the local EMC, usually around 9-12% in your area.
Form the original questioner:
Thanks for the info. You make good points. I'm using some of the lumber to panel the interior of the shop (rough-butted together), but I'd like to use the rest for a bedroom set. I'd like to panel the shop within 4-6 weeks, and begin the furniture within about two months. I'm hearing from local sources that my lumber may dry within that timeframe. Are these people being too optimistic?
I was sold on building a solar kiln until calling the local ag college and speaking with some locals. Then, given the timeframes they were giving me for air-drying, I would rather not incur the expense. I thought I might be able to fan-dry to speed things along. One professor said I would probably only speed up the process by about two weeks with a solar kiln. What are your thoughts? How long do you think it will take to air dry to a low MC then move it to the shop? (Shop is about 20-30% humidity.) How long would it take to dry this in a solar kiln if I place it in a kiln at the end of November? Would it dry too fast and degrade?
Your points about hydrating my shop are well taken. I believe I will set the charge outside. Thanks for saving my tools!
From Professor Gene Wengert, forum technical advisor:
If you air dry first, then three sunny days in a solar kiln will get you down to about 9% to 10% MC, the best level for furniture out of pine. If you go in at a higher MC, then expect 7 sunny winter days in Colorado. Fan drying of small quantities and narrow loads in CO is probably not that much of an advantage. Incidentally, a kiln of any type is a piece of equipment, and so would be depreciated on a business tax return as equipment.
From contributor W:
This time of year here in Eastern Oregon the semi-dry pine would probably equalize at 12% if it was stickered in full sun in about two weeks with top cover and good airflow. I can do it in about a week with juniper, then finish in the kiln to dry to 10% and kill the bugs. This is with wood not over 22% MC.
From the original questioner:
What kind of timeframe would you estimate to air dry some freshly cut "live" lodgepole? (One post gives me a good reference for the beetle-kill.) Plus, if I went ahead and built a kiln, wouldn't I just put the freshly cut wood in the kiln immediately in lieu of air drying first? If I did, what kind of timeframe would you estimate?
From contributor W:
To dry lodgepole pine from green in a kiln I have no idea. I go for the blue stain, so what I mill green I dead stack until it stains, then sticker and dry. Mostly I let the log sit for a while and then mill. I have no idea on a solar kiln. Mine is closed loop hot air system. But I will guess and say about 3 weeks. I never built one because in the winter we may not see the sun for weeks.
From Professor Gene Wengert, forum technical advisor:
You can go straight to the kiln, but you will need larger kilns with four weeks drying time. If you air dry, you will need half the kiln capacity and half the drying time (or less). Due to the high sunlight in Colorado, you will get good performance most of the year.
From the original questioner:
Thanks. Looks like a little outside air drying is in order for me. I'm still debating the kiln.
