Fresh Cut Sycamore

[charlese]

Gotta add a little here about water in wood and shrinkage.

Yes, Sycamore shrinks quite a bit when drying, however that shrinkage is not related to how much water the tree has when it is felled. In fact there are several trees that normally hold more water content than Sycamore. Cottonwood and American chestnut come to mind, and there is tupelo and baldcypress.

All the shrinkage comes about when a piece of wood gets dryer than fiber saturation. That means that all free water contained in the cell lumens is gone. No shrinkage happens at moisture levels above fiber saturation.

Reference - Wood Handbook Chapter 4 http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_04.pdf

[Ed in Tampa]

Gotta add a little here about water in wood and shrinkage.

Yes, Sycamore shrinks quite a bit when drying, however that shrinkage is not related to how much water the tree has when it is felled. In fact there are several trees that normally hold more water content than Sycamore. Cottonwood and American chestnut come to mind, and there is tupelo and baldcypress.

All the shrinkage comes about when a piece of wood gets dryer than fiber saturation. That means that all free water contained in the cell lumens is gone. No shrinkage happens at moisture levels above fiber saturation.

Reference - Wood Handbook Chapter 4 http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_04.pdf

Chuck
Help me understand. The water in the tree has to be held somewhere. When it dries out it either has to cause shrinkage or leave behind voids.
Since Sycamore holds so much water, enough that it appears you were in a shower when you get done cutting it, says there either has to be huge amount of shrinkage or a huge amount amount of voids.

I have looked at dried Sycamore and it doesn't appear to have huge open pores or grain so where does the water go and what replaces it when it dries out?

[jon]

Wow you guys are confusing me! A few months ago, on this forum, I saw pics of some bowls that were turned out of sycamore. They looked beautiful! That's why I took a chance and bought the fresh cut boards when I saw them. Now after reading all your posts, I am not so sure that I made a good decision.

My boss let me put the boards up in a rack at work (inside) where I plan to leave them for at least a year. I stickered them, painted the ends, and put cement patio blocks on top as was suggested by one of the readers on this forum. I hope I didn't go through all that work for nothing! Anyone have any final thoughts?? Did I make a big mistake?

[charlese]

Wow you guys are confusing me! A few months ago, on this forum, I saw pics of some bowls that were turned out of sycamore. They looked beautiful! That's why I took a chance and bought the fresh cut boards when I saw them. Now after reading all your posts, I am not so sure that I made a good decision.

My boss let me put the boards up in a rack at work (inside) where I plan to leave them for at least a year. I stickered them, painted the ends, and put cement patio blocks on top as was suggested by one of the readers on this forum. I hope I didn't go through all that work for nothing! Anyone have any final thoughts?? Did I make a big mistake?

No mistake! You did good!

[jon]

Whew! Thanks Charles.

[charlese]

Chuck
Help me understand. The water in the tree has to be held somewhere. When it dries out it either has to cause shrinkage or leave behind voids.
Since Sycamore holds so much water, enough that it appears you were in a shower when you get done cutting it, says there either has to be huge amount of shrinkage or a huge amount amount of voids.

I have looked at dried Sycamore and it doesn't appear to have huge open pores or grain so where does the water go and what replaces it when it dries out?

I'll try!

Where does the water come from in order to leave the wood? There is often a lot of "free" water contained in live trees. More so in hardwoods as opposed to softwoods. The free water contained in trees can often equal the weight of the wood fiber. (I believe a rule of thumb is 50%) However a table in chapter 4 of the wood handbook shows that water (moisture) in Sycamore is around 114% in heartwood and 130% in sapwood. How can the tree hold this much water? Sycamore is a diffuse porous wood having many evenly space vessels throughout each annual ring. This "extra" water (quotes mine) was pumped up by the leaves over time and stored as free water in the hollow center(s) (lumens) of the many vessels. There is no efficient way for this water to fall back down into the roots as now, as the tree grows, the water is held in the physiologically dead heartwood. Meanwhile the phloem and sapwood are still raising water.

"Free" water is contained in the lumen of vessels (the open center of those large cells [called vessels]) in hardwood. When the lumen is not filled with water or tylosis, they are open and also interconnect. As an example, take a 1/2" X 1/2" X 7" or 8" stick of straight grained red oak, stick one end into a glass of water and blow on the other. You will make bubbles. I haven't tried using the oak as a straw! But this will illustrate that air can easily flow through several inches of what we think of as solid wood. You can probably do the same thing with sycamore or walnut or most ring porous and diffuse porous hardwoods. NOTE: If you try this with wood having diagonal grain, the air will come out of the side of the stick.

Now some guy comes along and puts a saw into the tree. much of that water under the weight of the column, comes running out of the cut.

What replaces the water, when it dries out? Air and voids. When this free water is gone, the wood still contains hygroscopically held water or bound water. At this point the wood still contains about 30% water. This is the point where shrinkage starts. Now the wood will continue to dry until it reaches an equilibrium with the relative humidity in the surrounding air. +-+-

[robinson46176]

Sycamore can have beautiful grain. Other than what you are doing my only warning is do not try to use it left unfinished for anything other than rough construction. Where possible finish it on all possible sides to help keep it stable. Many pieces of furniture are not finished underneath or on the backs but sycamore should be as sealed as possible to keep it from drawing moisture.
There are 3 old timber-frame barns here on my farm, all framed with sycamore cut here on the farm about 100 years ago. It was cut and used green. It serves that function well as long as it is protected from moisture. It is not a rot-resistant wood in wet locations.

[jon]

Thanks for the tip! I will use the lumber for an indoor project.

[jon]

Thanks for the tip! I will use the lumber for an indoor project.