Toasted oak vs. bog oak?

[Bert2368]

I keep seeing references to bog oak in knife handles here, I have never used this material and don't know how it behaves as far as stability towards moisture and general durability against handling wear. It certainly does look nice in some uses.

I DID see it written that an attempt to make the black keys on a much used organ keyboard from bog oak wasn't satisfactory due to high wear, leading to an early replacement. I suspect that unstabilised bog oak is not as durable as ordinary oak?

I did a small batch of "torrefied" white oak very recently. The oak turned a range of colors from medium to dark brown, not the really dark grey/black of the bog oak I see others have used.

I am considering using a couple of the scraps of the heat treated oak for an experiment in "fuming" it with ammonia gas, this is a common technique to darken oak and some other woods.

https://en.m.wikipedia.org/wiki/Ammonia_fuming

You can get normaly dried white oak to turn nearly jet black with a long enough fuming session, although the color doesn't extend all the way through thicker pieces of wood as the heat treat color change does.

I have NO idea what the heat treatment may have done to the tannins in the wood which are what react with ammonia and artificially darken the oak, or if this will work at all after the heat treatment.

Anyone got a clue about this?

(Below are some pictures of heat treated oak, will post experimental results later).

 

[Bensbites]

I have ebonized (iron acetate from vinegar/steel wood) oak. This is only a surface treatment and sands off quite easily. I have used this on stabilized and unstabilized oak. A member here has a handle made from the material. Let’s see if he chimes in.

 

[Bert2368]

The acid and Iron treatment is essentially the same thing which can happen in a bog- Acidic water + traces of Iron in the water. In fact, some of the earliest Iron smelted in what is now the USA was "bog Iron":

https://en.m.wikipedia.org/wiki/Bog_iron

In a bog over several centuries (or millenia?!) the chemicals from the bog water completely permeate the wood, unlike the surface treatment we can do in a reasonable ammount of time with some steel wool and white vinegar.

Ammonia is the reverse of an acid: A strong base. I need to refresh myself on the chemistry involved.

 

[daveb]

I've had both an early non-stabilized bog oak handle and a couple of stabilized ones. The only difference I found was that the un-stabilized one needed almost constant oiling to stay looking good. The stabilized ones needed little to no care. My next re-handle will be a particularly nice piece I've had stashed from Burl Source for a couple three years.

I did not work with the blanks at all - with my skill set I have to hire that done.

 

[McMan]

Cool you should bring this up! When you posted a little while ago about baking maple, my first thought was what about ammonia-fuming... I think it's great that you're experimenting with some of these old school finish methods.
The only reason I know about fuming is because of Stickley furniture. Stickley was big on ammonia fuming and experimented with acid(s) and fuming in combinations. (Some tell the story that he was continually just throwing junk into the ammonia and then combinations of techniques.)

http://www.woodcentral.com/woodwork.../id/420907/sbj/fuming-and-stickley-finishing/
https://artsandcraftshomes.com/interiors/fumed-oak-wood-stains

 

[MrHiggins]

... Stickley was big on ammonia fuming and experimented with acid(s) and fuming in combinations...

Sounds like my High School experience!

 

[Bert2368]

Sounds like my High School experience!

http://southpark.cc.com/clips/150390/chefs-advice

 

[Bert2368]

I went looking for the chemistry of the ammonia gas/wood darkening reaction. Turned out there was a good reason I don't know what exactly is going on... NO ONE seems to REALLY know.

If you have a chemical engineering background, this link may be of interest:

https://bioresources.cnr.ncsu.edu/resources/wood-color-changes-by-ammonia-fuming/

What I took away:

Woods without significant tannin content get darkened too, it just takes longer. Tannins may speed up or mediate the changes but are not absolutely required

The chemical reaction(s) result in at least the nitrogen from the ammonia (ammonia gas is NH3) being retained in the wood.

Whatever the darkening compound(s) is/are, they are related to the fraction which may be extracted from wood by an ethanol/benzene mixture (non polar solvents). So darkening effects are going to be COLOR FAST, against water, at least. I guess I already knew that, but nice to see a reason why this may be so.

And that truly deciphering the biochemistry of living or formerly living materials is still bloody complex!

 

[inferno]

I would guess bog oak is a bit more fragile and brittle than all kind of chemical treatments you can do yourself to oak.

ethanol is a very weak solvent in its polar range and i guess its just about dipole moments and dielectric constant.
here is a chart. i think you can find more on wiki. a lot more!
https://en.wikipedia.org/wiki/Solvent#Physical_properties

 

[Dan P.]

I use a lot of bog oak and I find it tougher to work than regular oak. The millennia spent steeping in tannic water seems to plasticize it to some degree. That is not to say that it is stabilized, or indeed tough in a structural sense, and oak of any kind will vary according to the individual tree, part of the tree, how it was cut, the density of the grain, etc. It's a fairly open grained wood whatever the case, but bog oak will easily take a lustrous finish that regular oak might not, and is generally a more attractive proposition, in my opinion, aesthetically and practically.