Cedar.....do the cells die when it gets brittle...is this dry rot?

[Norske3]

I have some "old" cedar planking scrounged off a boat built in the fifties......I was thinking of using some of it to build a "dink"...until I stepped on a plank one day and it broke straight across the board with very little splintering...its brittle....so is that like dry rot?.

[ 01-17-2006, 07:46 PM: Message edited by: Norske3 ]

[Dan McCosh]

How thick was the board?

[Norske3]

Thickness.....5/8ths.

[Andreas Jordahl Rhude]

There is no such thing as "Dry Rot." I hate that term.

[Dan McCosh]

Rotted white cedar tends to turn brown. Doesn't sound like rot--you may just have had a defective board

[Frank E. Price]

Western red cedar is pretty brittle at its best, but wood stored that long could be infested with cooties. Maybe Smalser will clue us in.

Frank

[Bob Smalser]

Likely rot. But could also be brash wood.

"Brash" wood as you describe likely wouldn't survive bending into a plank. Brash wood comes from severe stresses in the tree as it grows, either from the wind or trying to hold itself straight on a steep slope. When the fibers shear in growth, they don't heal themselves.

Even the best cedar heartwood will rot eventually under the right conditions, and a streak of sapwood left in there just hastens the process.

[Three Cedars]

No it is not dry rot.

The wood is 50 years old , it has undergone thousands of wet/dry cycles, been baked in the sun, frozen in the winter. The lignin has mostly been leached out,leaving the wood very brittle. You might be able to use it for interior paneling but that is about it. Makes great kindling smile.gif

[Bob Smalser]

While I agree old wood becomes brittle from age due to lignin loss, my observations of brittle wood were in antiques much older than 50 years.

The USDA says lignin loss only occurs on the surface or unpainted wood to a max depth of half a mm. When the rain washes the deteriorated layer away, the process repeats itself. It takes a while, and the wood thins along with the process.

In this recently-glaciated part of the world, all the skinny floating snags you see in old beaver ponds were Doug Firs over 30" in diameter or larger a few thousand years ago, when the creeks were dammed and the trees drowned. The wood beneath the deteriorated layer is usually as resilient as it ever was.


The photochemical degradation of wood
due to sunlight occurs fairly rapidly on the exposed wood surface (29,31). The initial color change of wood exposed to sunlight is a yellowing or browning which proceeds to an eventual graying. These color changes can be related to the decomposition of lignin in the surface wood cells and are strictly a surface phenomenon(18,30). These changes occur only to a depth of 0.05 to 0.5 mm (38), and are a result of sunlight particularly ultraviolet (UV) light which initiates photodegradation. Such photodegradation by UV light induces changes in chemical composition, particularly in the lignin, and subsequent color changes http://www.fpl.fs.fed.us/documnts/pdf1983/feist83a.p df (http://www.fpl.fs.fed.us/documnts/pdf1983/feist83a.pdf)

[ 01-19-2006, 10:36 AM: Message edited by: Bob Smalser ]

[Dave Carnell]

"Dry Rot" does not exist. Rotting requires oxygen (air), water, and rot organisms.

There is a thriving business here in NC recovering waterlogged longleaf pine logs that sank in the rivers and milling them to beautiful wood. The Navy stored live oak timbers for repairs to USS CONSTITUTION under water for decades at the now-defunct Charlestown Navy Yard.