Sodium nitrite test?

[Steve Lansing]

Has anyone had success identifying white oak with the sodium nitrite test?

[Don Stephan]

Can distinguish red from white oak by slicing a thin section across the grain and place a few drops of water or alcohol on the upper surface. Liquids will pass through red oak quickly but not through white oak. That's why wine barrels are made from white oak and not red.

[Bruce Wrenn]

Can distinguish red from white oak by slicing a thin section across the grain and place a few drops of water or alcohol on the upper surface. Liquids will pass through red oak quickly but not through white oak. That's why wine barrels are made from white oak and not red.


Back in the day, vendors would pass cigarette smoke thru red oak shorts at trade shows to show how red oak has hollows running the length of the piece.

[Stan Calow]

I'd never heard of the sodium nitrite test, but sounds like it works well enough for pros to use. I once sorted through a whole basement of mixed oak boards for sale, picking out the white oak, and a quick non-destructive test like that would have been useful.

[Jason Evans]

Can distinguish red from white oak by slicing a thin section across the grain and place a few drops of water or alcohol on the upper surface. Liquids will pass through red oak quickly but not through white oak. That's why wine barrels are made from white oak and not red.


That’s interesting. I was just wondering if a board I milled was white or red oak. Seemed darker than the rest. Not sure exactly what you mean. When you say slicing a thin section across the grain, do you mean crosscut a board and pour water on the upper end grain? Or resaw a board and use that thin slice?

[Lee Schierer]

That’s interesting. I was just wondering if a board I milled was white or red oak. Seemed darker than the rest. Not sure exactly what you mean. When you say slicing a thin section across the grain, do you mean crosscut a board and pour water on the upper end grain? Or resaw a board and use that thin slice?

Here is a visual demonstration (https://www.youtube.com/watch?v=QGaQsrNuZYk) of air passing through red oak pores. You can't do that with White Oak.

[Jason Evans]

Here is a visual demonstration (https://www.youtube.com/watch?v=QGaQsrNuZYk) of air passing through red oak pores. You can't do that with White Oak.

Thanks a lot Lee. I get it now. Also, that was pretty entertaining to watch someone blow bubbles with a piece of red oak.

[Simon Dupay]

Thanks a lot Lee. I get it now. Also, that was pretty entertaining to watch someone blow bubbles with a piece of red oak.
One exception to this rule is chestnut oak which does not have tyloses (https://en.wikipedia.org/wiki/Tylose), but is still considered to be in the white oak group

[John K Jordan]

Has anyone had success identifying white oak with the sodium nitrite test?

No me. I simply shave a tiny (maybe 1/4”) smooth spot somewhere on the end grain and look at it with a hand magnifier. The type is instantly revealed. Learning this simple thick opens windows for identifying many species. For the oaks the ray length on a radial surface also distinguishes between red and white classes.

The book Identifying Wood by R. Bruce Hoadley was an enlightenment.

EDIT: sodium nitrate can be a severe health hazard, use with care. My wife had a severe cut cauterized at the dr’s office, her most painfil experience yet, like taking a red hot soldering iron to the wound.

https://nj.gov/health/eoh/rtkweb/documents/fs/2258.pdf

JKJ

[Prashun Patel]

I have used the sodium nitrite test. It's very cool. White oak will turn black and green, red oak slightly brown.

The black color for white oak is not permanent. It will lighten to a dark brown eventually - within days. Red oak will also be permanently altered to a dark brown. This works very well on green wood, and diminishes over time with dried lumber.

For green wood, an easier test is to look at the leaves and smell the cut lumber. White oaks will smell more like coffee and cream. Red oak will smell like vinegar or ketchup. It can make your eyes water...

If you're working green, the best test is to split a portion with a hatchet. Red oak will rive easily - awesome for anything straight. White oak is more stringy, which makes it better for bending.

[Mel Fulks]

If you need to test red oak to find out if it has holes in the ends , then you probably really miss the BIG SCREEN drive-in movies. Where at
ZEE
Refreshment Stand the “ The Popcorn is HOT and DRINKs are ICE COLD “ Red oak end grain has holes in it . White oak end grain is filled …
with something.

[Steve Lansing]

No me. I simply shave a tiny (maybe 1/4”) smooth spot somewhere on the end grain and look at it with a hand magnifier. The type is instantly revealed. Learning this simple thick opens windows for identifying many species. For the oaks the ray length on a radial surface also distinguishes between red and white classes.

The book Identifying Wood by R. Bruce Hoadley was an enlightenment.

EDIT: sodium nitrate can be a severe health hazard, use with care. My wife had a severe cut cauterized at the dr’s office, her most painfil experience yet, like taking a red hot soldering iron to the wound.

https://nj.gov/health/eoh/rtkweb/documents/fs/2258.pdf

JKJ

Thanks for the book recommendation, I’ll order it.

Your story about your wife’s “severe cut” being cauterized by a DOCTOR? was quite a surprise since I was told by my Dr. many years ago that that was not a good idea especially on a deep cut.

[Steve Lansing]

I have used the sodium nitrite test. It's very cool. White oak will turn black and green, red oak slightly brown.

The black color for white oak is not permanent. It will lighten to a dark brown eventually - within days. Red oak will also be permanently altered to a dark brown. This works very well on green wood, and diminishes over time with dried lumber.

For green wood, an easier test is to look at the leaves and smell the cut lumber. White oaks will smell more like coffee and cream. Red oak will smell like vinegar or ketchup. It can make your eyes water...

If you're working green, the best test is to split a portion with a hatchet. Red oak will rive easily - awesome for anything straight. White oak is more stringy, which makes it better for bending.

Thanks for your response, that’s what I was looking for.
I figured I would get many of the usual methods - that we’ve all used - so someone actually answering my question is greatly appreciated!

[Scott T Smith]

Hi Steve. I think that I answered your question on a different forum.... (grin)

Good info from Prashun above (as always). Usually I'll see a dark brown color in 15 minutes with a drop of sodium nitrite on WO, and a light brown color on red oak.

Another trick is to measure the length of the medullary rays visible in flat or rift sawn lumber. Red oak's rays will not exceed 3/4", whereas white oak will.

Best of success to you.

Scott

[Prashun Patel]

Sorry for the non-professional pictures.

I applied a (roughly) 10% sodium nitrite solution to a few samples (3 in the middle were dipped; left most and right most were applied with a dropper).

The 4 samples on the left are what I believe to be white oak. The leftmost chunk is air dried, 10 years old. The middle 3 are kd; the right red oak is air dried (3 years old).

This first picture shows the results after 2 minutes.

486488

This second picture shows the results after 45 minutes. I was shocked that the red oak was black. I was shocked that the left sample (also a from my yard) was brown when I know it to be white oak. I believe it is on its way to black, though.
I shaved some of the end grain from each of the suspect boards and re-dipped them.

The three middle samples show what white oak typically looks like after an hour. Grey/green/black. This will ultimately turn brown over the next few days/weeks.

486489

You can see below that the white oak end grain did indeed turn black; this was about 20 minutes after dipping. Even the wiped off original stain is showing a grey/green stain now.

486490

The red oak still looks black. Puzzling...

486491

... but when I look at the end grain up close (red oak on top, white on the bottom), it does appear brown (at least between the flecks).

486492

Anyway, enjoy. My nonscientific takeaway is that this test might work best on the end grain, and in the end it might best be used only to confirm what you suspect.

The effect of the sodium nitrite almost feels like fuming.

I wish i knew a chemist who knew wood. From what I know about different species of related botanicals, there is variation between individuals of the same species, and similarities between individuals of different species. So, it might just be that this test is only telling us the relative iron(?) content of the boards, and not the species in particular? Talking way out of school. Walter White, where are you?!

[Steve Lansing]

Hi Steve. I think that I answered your question on a different forum.... (grin)

Good info from Prashun above (as always). Usually I'll see a dark brown color in 15 minutes with a drop of sodium nitrite on WO, and a light brown color on red oak.

Another trick is to measure the length of the medullary rays visible in flat or rift sawn lumber. Red oak's rays will not exceed 3/4", whereas white oak will.

Best of success to you.

Scott

Yes, I saw it - Thanks, I appreciate it.