Properties of Wood - Whats important and whats not?

I feel i should state what I have currently got on my little list…

-Strength properties (tension, compression, sheer, torsion etc)
-Shrinkage/Expansion
-different types of seasoning (not really a property of wood, but important)
-Sawing methods and how they effect the stock (Through&Through, Quater Sawn, Back Sawn etc)
-Grain (I dont know where to start with this one, but i know its important to include)

As you can see, I really am stuck, its quite hard to think about what you should get into the head of a 13 year old, and what isnt necessary

-- Jordan - http://www.jordswoodshop.com

Demonstrations hold their interest. Like taking 2 long thin pieces of wood, 1 white oak and 1 red oak and putting them into a glass of water and blowing into each one to show that one has open cells and the other has closed cells. (white oak has open cells if I remember correctly). One of the great woodworking teachers, boy I cannot remember his name, used to open his first class by being late, walking in and saying nothing, going to his steam box, taking out a piece of wood and to the amazement of his new students would go about tying a knot in the wood. Now that would be impressive. I work with Boy Scouts of this age they love demonstrations and cannot stand lectures. I don’t know if you are old enough to remember – Don Herbert as Mr. Wizard on Watch Mr. Wizard – but that’s what you have to do with these age kids. See “Watch Mr. Wizard” on YouTube to get an idea. Make it fun and make it revelant.
MIKE

-- See pictures on Flickr - http://www.flickr.com/photos/44216106@N07/ And visit my Facebook page - facebook.com/MTEnterprises

We do the same thing with the Oak on “Bring your Kids to Work Day” in the office. Take a piece of Red Oak and a piece of White Oak. Dip one end of endgrain in soapy water of each piece and blow through it. The Red Oak makes bubbles (due to the open pores), whereas the White Oak will not (due to “Touloses” clogging the pores).

-- Ryan - Bethel Park, PA

I may suggest:
Knowing what direction grain is going, tools react differently to upward grain as opposed to downward grain. Hand Plane would demonstrate that very well.
Finishing properties: Different penetration of finishes. (Charles Neil states it better, when he brings someone into his shop to build they pick out a finish before they start building, different woods react differently to finishes)
Hardness: Some wood is good for carving, some for furniture.

-- "My mission in life - make everyone smile !"

Ok so I got it backwards. I stand corrected.
MIKE

-- See pictures on Flickr - http://www.flickr.com/photos/44216106@N07/ And visit my Facebook page - facebook.com/MTEnterprises

My old wood science college professor always said that all the important properties of wood can be explained by the cellular nature of wood. I would begin by showing a micro photograph of the end grain of some different woods so the students can understand what wood cells look like. There is some really good information here.

-- Bondo Gaposis

Kudo’s for stepping up to educate our youth on woodworking; it may lead to a career in wood, wrought iron, steel machining, pottery, so many options. And from there, my recommendation is to state that there is way too much to cram into a half hour, and that the finer aspects can be learned in a dedicated classrom. To get them to said classroom, I would recommend the above suggestion of wood properties as well as a finished product of visual beauty sitting side-by-side to a 2×4; this would give 2 clearly differing outcomes for 2 different purposes in woodworking, hopefully opening their imagination to the thousands of opportunities between them. Best of luck!

-- Power tools put us ahead of the monkeys

I’m thinking the properties of wood would be, strength, density, color, rot resistance, grain patterns, including burrel, flexability, and possibly the places different woods grow. How these properties affect wood we use for various things. For example, redwood or locust for fence posts, ash for baseball bats, walnut for furniture, mesquite for smoking food, Douglas fir and hemlock for home building. Bring samples….
To keep’em interested ask lots of questions for them to answer.

-- Les B, Oregon

Along with what others were saying, and Les hit on it a bit, I think it would be beneficial to know what the properties are of wood (hardwoods, softwoods, ply, MDF etc) are, and how they impact the decision making process when approaching a project. For instance, if I’m designing a floor cabinet for a bathroom, I might need to consider that MDF’s sponge-like properties might make it lower on my list. Perhaps it might also be appropriate to discuss design factors that need to be considered when using a combination of solid and ply.

I don’t know what the students’ history is with design/construction of projects, but I think one of the most useful lessons that can be learned is a general lesson on approaching a design with a problem-solving attitude.

- What is the project?
- What are the constraints of the project?
- What are the expectations of the project?
- What wood do I choose? What are the positives and negatives of this wood, and how will that impact my project, both during construction and as a finished item?

Being a SW engineer by trade, I value someone who possesses independent-thinking and problem solving skills. You want people who can self-lead, and don’t need someone to hold their hand through everything. I think they need to know not only what the properties are, but how to use that knowledge in real-life.

-- - The mightiest oak in the forest is just a little nut that held its ground.

Thanks for all the responses!

Getting a nice little list going now, shouldn’t be too hard to fill 30 minutes and with some examples that i didnt think of, Like blowing through the red/white oak, thats a great one!

Regards
Jordan

-- Jordan - http://www.jordswoodshop.com

Jordan,

I would search the web for a woodworking project where the builder didn’t take into account wood movement. Show them how a piece of furniture can tear itself apart because wood movement was taken into account.

I am a faculty adviser for the local high school vocation teachers. I specialize in the woodworking side of the house. One of things I teach the kids is they MUST take into account with any project they are building from solid wood, that the wood is going to move and there is nothing they can do to stop it. They must design a project to take into account the simple fact that wood moves over the course of a year with seasonal changes. Combine this with wood strength, density and workability (cutting, carving, screw/nail holding power, etc.) and you will be keeping their attention because all these properties have a very direct impact on the success or failure of their projects they are going to do in wood shop.

Showing a bunch of testosterone crazed kids a picture of something all busted up and you have their attention. At least in my experience…. :-) I tried to find the pictures I showed a couple of years ago but I can’t find them otherwise I would post them here for you.

-- Don, Diamond Lake Custom Woodworks - http://www.dlwoodworks.com - "If you make something idiot proof, all they do is make a better idiot"

Here’s a link to a series of short articles I’ve done which include some on wood properties. The green lines are links that will take you to the actual article.

Woodworking Articles

The relationship between moisture and wood is what I consider the most important. It’s where most newcomers to woodworking run into a lot of problems unless they are pointed in the right direction first.

I also recommend Hoadley’s Understanding Wood.

-- See my work at http://remmertstudios.com and http://altaredesign.com