Differentiating White and Red Oak Lumber

[Bob Smalser]

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The best method is under a scope using cell structure comparisons contained in botanical keys, but if all you need to know is whether or not you have oak suitable for use in boats, you can accomplish that just as well using a razor blade and 10X hand lens. The 10X hand lens used in sunlight will provide much greater definition than these photos.

What makes the White Oak group of oaks suitable for marine use (and oaken barrels), is their large, earlywood pores (the fresh, new wood formed each Spring) are clogged with whitish, waxy tyloses that water won't penetrate. The Red Oak group of species lack these tyloses, allowing water to penetrate and the wood to literally weep and seep at the end grain. This combined with other factors causes the Red Oaks to be subject to the rapid onset of mold, fungus and rot.

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White Oak end grain. Note the whitish tyloses clogging the large, earlywood pores forming the pith or inner edge of each annual growth ring.

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More White Oak end grain.

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Red Oak end grain. Note the relatively clean earlywood pores.

A home method to test for Red Oak is to cut it into short soda straw sections and see if it will blow bubbles into a glass of water. This generally isn't a very reliable method because sawdust from crosscutting the sample often clogs the pores. If you use it, then slice away the end grain and any sawdust contamination first using a razor blade. The 10X hand lens is more reliable.

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Blackjack Oak. In the Red Oak group but here the pores are clogged with sawdust, not tyloses.

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More Red Oak lacking tyloses.

Continued......

[Bob Smalser]

Continued....

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Live Oak end grain with tyloses.

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More Live Oak.

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Bur Oak end grain sliced clean using a razor blade. Tyloses are definitely present, indicating Bur Oak is a White Oak and boat wood.

[Gary Breckenridge]

Another way to tell red oak from white oak is to build a boat with all different kinds of oak purchased from different lumber yards. The wood that rots and leaks after a year is red oak and the wood that is still solid is white oak.;)

[Mac McQuinn]

Gary,
Is that wink a sign of experience in this matter??:cool:

Mac




Another way to tell red oak from white oak is to build a boat with all different kinds of oak purchased from different lumber yards. The wood that rots and leaks after a year is red oak and the wood that is still solid is white oak.;)

[Sean Hughto]

I don't use a ton of oak, but white oak has always seemed significantly heavier (given like sized pieces of each). Also, white oak has a certain somewhat unique smell (the smell I used to associate with original mission furniture). Am I imagining these things because I haven't been around enough oak?

[Terry Rogan]

To toss in some more info on this one...

Another way to tell R/O from W/O is by the average length of the rays when looking at the long grain.

Rays are the little darker streaks that are found throughout both Oaks, and on R/O, you'll find that the rays are generally 3/16" to 1/4" long while on W/O, the rays can average about an inch long and often go to a couple of inches.

Jus' tryin' to help. ;)

[Robert Parrish]

Well you could send me some samples! I'm deathly allergenic to white oak but not red oak. Go figure.

[Terry Rogan]

Well you could send me some samples! I'm deathly allergenic to white oak but not red oak. Go figure.

Here 'ya go, Robert.
In the pic below, pay particular attention to what appear to be the darkest streaks in both wood samples.
What you're looking for is for a preponderance of short streaks in Red Oak as in the top half of the pic, and a preponderance of long streaks as in the White Oak in the bottom half of the pic.
Yes, Red Oak can have "some" longer streaks, and White Oak can have "some" shorter streaks, but you can reliably tell one from the other by how much longer most of the streaks are in White Oak and how most of the streaks (rays) in Red Oak are shorter.
On average, I'd say that the rays in Red Oak are generally 1/4" give or take, and the rays in White Oak are an average of 1-1/4", give or take.

Hope that helps.

[curtis rosche]

there is a thread from awhile ago on this that was posted in the turning forum, and there is a link to a video on it. red oak, if the ends are cleanly cut and it is a straight peice, you can take a peice that is 18 inches long and blow on one end like a straw, and blow bubbles underwater. check out the video if you find that thread. it is really cool