Archive for the ‘Help with Issues’ Category

Wood Movement Issues

Thursday, January 17th, 2013

Think that once you finish your wood project, that’s it. You brush your hands together, stand back a few yards and your eyes begin drooling at the site of a handsomely created, exotic wood structure. As it ages, the value shoots through the roof. It grows into something more than simply practical. It evolved in beauty.

But just because legs on a chair are not meant to walk, wood moves. Some lumber likes to shift around more than others. So, if you’ve left this addendum to your Last Will and Testament,“ that reads, “This (fill in the name of the object) shall remain in the family until October 14th, 2155. At that point, it will be given to my favorite museum.”

That’s all fine-and-good. However, if the objet d’art has twisted and wiggled into some grotesque, child-scaring thing in 140-odd years, the museum will probably pass on the gift.

Hardwoods and Softwoods

We already have a handle on these two types. What differentiates the pair is where they stand on the Janka Hardness Scale (JHS). The higher the number, the harder (or softer) the timber. For instance, Quipo from South America rolls a 22 on the JHS. Then there’s Buloke Australian from down under. Its JHS is a whopping 5060.

What makes one a softie and the other so dense? Hardwoods have pores to move water around beneath the bark. Softwoods shift the H2O using fibrous-like cells.

Why should you care? It’s simple. If the lumber can suck-in moisture after it’s been felled, it’s going to expand. Technically this is called movement in service.

The shifting happens across the grain. And don’t think that by finishing the wood going you’re arresting the movement. It merely shifts it into 1st gear, but it still expands.

The Guide

It’s not a full list, but it will give you a start. We’ll begin with the lumber that’s going to move the most and work our way down to the stuff that’s pretty stable:

You’ll see the most shifting in these woods:

  • Beli
  • Yellow Birch
  • Ekki
  • Esia
  • American Red Gum
  • Holly
  • European Hornbeam
  • Pink Ivory
  • Karri
  • Keruing
  • East African Olive
  • Ramin
  • Rata
  • Stinkwood

Now for the guys that will fall into the average wood movement class:

  • Akossika
  • Andiroba
  • Bayo
  • Beech
  • Berkung
  • Blackbean
  • Butternut
  • Cancharana
  • Chakte Kok
  • Chakte Vega
  • Cherry
  • China Berry
  • Chinkapin
  • Gaboon Ebony
  • Elm
  • Hackberry
  • Indian Laurel
  • Jabin
  • Katalox
  • Kapur
  • Australian Lacewood
  • Lam Nhai
  • Leng Man
  • Lignum Vitae
  • Hard Maple
  • Machiche
  • Morado
  • Red and White Oak
  • Paela
  • Paldao
  • Black Palm
  • Peroba Rosa
  • Poplar
  • Pyinkado
  • Rimu
  • Sapele
  • Snakewood
  • Sycamore
  • Taun
  • Tchitola
  • South America Walnut
  • Yom Hom

This lumber is considered to be in the slight movement category:

  • Apple
  • Ash
  • Aspen
  • Arariba
  • Balau
  • African Blackwood
  • Ben Se
  • Chechem
  • Curunai
  • Curupixa
  • Cuta
  • Cypress
  • African Ebony
  • Flamewood
  • Fang Deng
  • Freijo
  • Goncalo Alves
  • Guatambu
  • Honey Locust
  • Hug Lon
  • Jelutong
  • Kaki
  • Kauvula
  • KOA
  • Makore
  • Maple
  • Mesquite
  • Muhuhu
  • Nontsia
  • Ochoo
  • Pecan
  • Prima Vera
  • Purpleheart
  • Brazilian, Cocobolo and Honduran Rosewood
  • Sarari
  • Sassafras
  • Bloodwood Satine
  • Ceylonese Satinwood
  • Redwood
  • Ta Baek
  • Tarara Canarywood
  • Teak
  • Brazilian Tulipwood
  • American Walnut
  • Wenge
  • Willow
  • Xang Seak
  • Yew
  • Zebrawood

Finally the winner of the no or very little movement club are the following:

  • Red Alder
  • Aningeria
  • Antiaris
  • Balsa
  • Bamboo
  • Basswood
  • East African Camphorwood
  • Spanish Cedar
  • Cuchi
  • Curupay
  • Ipe
  • Jequitiba
  • Maracaibo Boxwood
  • African Padauk
  • Pear
  • Yellow Pine
  • Rengas
  • Indian Rosewood
  • Sen
  • Tatajuba

One final note. Notice the last group. In it is one of the hardest commercial woods – ipe. When you measure it, ipe wood on the JHS is well over 3500. On the other hand, balsa is on that same list. Its JHS is a mere 88.

In the not too distant future, we’ll explain how this works.