Drying sinker wood

      How does one begin drying wood that's been submerged in water for many years? June 27, 2000

Q.
Would anyone out there have any clue how to go about drying hardwood that has been underwater for about 100 years? Some of the boards I've brought inside have cracked (the ends weren't coated). Now, considering that I coat the ends of the logs and saw them up...what's the best way to air-dry the lumber?

I have a barn available with a concrete floor. Would it be better inside with an exhaust fan or a circulating fan? Or would it be better outside, with a cover on the top? I realize that this wood no longer has any sap, so drying will be different.

Some of the boards will be as wide as 20 inches, and it would be a shame to have them crack! Most of the logs are birch and maple, and I really need some advice here. I've got about 100 of these logs behind the house in the field right now, and I don't want to lose them since it's valuable, old-growth timber.

A.
You must move very fast to saw the logs you have into lumber, or they will quickly deteriorate.

The wood is weaker than normal and has more water. End cracking is a high risk.

You need to dry the wood more slowly than normal -- more gently -- to avoid checks and cracks. Generally, use a kiln schedule that is one letter milder, two numbers milder for relative humidity, and three steps milder for temperature. For example, T6-D6 would become T3-C4.
Gene Wengert, forum moderator



The only difference between "sap" and water is the very small amount of chemicals (mostly sugars) in sap. These chemicals tend to cause the sap to adhere to the cells' walls more than water. This would increase the tendency for collapse to occur.

However, logs that have been submerged for a long time would have more liquid in them than fresh-sawn lumber. This too would cause more collapse. The biggest difference would be that the sunken lumber will most likely have bacteria in it that would weaken it, and have more tendency to check.

There has been no research comparing the difference between drying fresh-sawn lumber and saturated lumber. The suggested practice is to cause it to dry more slowly initially, until the free water is removed, then increase the drying rate.



From the original questioner:
Should I dry it in the barn then? Should I ventilate the barn, or let it dry normally at first? Would two coats of oil-base paint be OK for the ends (genuine coatings are hard to find around here and very costly to buy from the U.S.).

How long can the logs stay out before they have to be sawn? Is there a phone number that I can call someone to discuss this thoroughly?

A.
You need to search the archives here at WOODWEB for more information about sunken timber. There are too many variables to answer your questions, but usually oil-base paint does not work well in cases like these.

As for drying, the barn is probably a better choice, but there are too many other questions for me to knowingly say that it is the best choice.

To be safe, you need to watch and inspect the lumber every few days, looking for potential damage. Books on drying are hundreds of pages, so I cannot give you an entire course in this forum.
Gene



The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
The key to drying sinker logs is patience. Get them sawn as soon as possible after removal from the water. If it will be several weeks before sawing, keep them wet and covered with a plastic tarp to prevent evaporation. Saw the logs 6/4 (1 1/2 inches thick) so you have plenty of room for shrinkage and planing to get to a 3/4" board. After sawing, pack the lumber tight in an enclosed building. I use 1 inch spacers every 16 inches with 3/4 inches between each board, ie, side by side.

Be sure to put lots of weight on the top of the lumber when finished stacking to keep them from warping. It is best to do this in the fall if possible. The temperatures are lower than in summer and the boards will dry slower and that is the key. Fast removal of the water equals disaster.

After 8-10 weeks, the moister content should be around 40%. At this time, use a kiln to remove the remaining moister to 4-6 % using the same stacking procedure. You will now have a 1 inch board that can be sanded or planed to any dimension you want.



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  • KnowledgeBase: Primary Processing: Air Drying Lumber

  • KnowledgeBase: Wood Engineering: Wood Properties

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