Methods for Finishing Bog Oak

Horsewright

Horsewright

Knifemaker / Craftsman / Service Provider
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Oct 4, 2011
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I’m re handling one of my knives, for a customer, with Culloden Bog Oak. This is to celebrate his Scottish heritage and his upcoming wedding. I’ve never worked bog oak before. How do you finish it, any tricks or hazards to be aware of?
 
I stabilize all my bog oak. From there it works pretty much like ebony.

Use sharp fresh belts and avoid heating the wood. Use slower speeds. Take to a reasonably fine finish (800-1000) and buff lightly ... avoiding heat.

If it is unstabilized,
Use fresh sharp belts and shape gently and slowly to avoid splintering.
Once sanded to the final shape at 400 grit, flood the surface with CA and let dry an hour.
Wipe off the excess with a soft cloth dampened in acetone or nail polish remover. Rub hard while removing the excess.
Let dry overnight.
Re-sand at400 grit and reapply the CA.
Repeat a time or two more if needed.
Sand the last step up to the desired final grit and buff lightly.
 
I would just add to double down on your best respiration ppe. Ancient bog oaks makes super fine black dust like soot…I remember the lines on my face around the respirator lol.

Grain structure for grit progression is similar to normal oak but the voids between grain lines seem bigger to me. Not much improvement in finish after about 600 grit for my results. My 2 cents buddy 😊
 
It likes to blow up when you grind it too aggressively. I finish to a super clean 220-280, maybe hand sand to 320.

I like to garnet blast to show texture. A high finish isn't really needed past getting scratches out.

I bought a bunch for folders. I'm just going to hand sand the scales with a guitar fretboard radius block to shape.
 
Same as above, it's splintery, pores need to be filled in either with oil/sanding dust slurry or CA.
 
I apologize if this is derailing, but have any of you played with "ebonizing wood" with iron acetate? I'm wondering how This looks like compared to bog oak?

Is it safe to assume big oak is just nature's long, drawn out version?
Id like to hear from the experts

I made one handle So far with ebonized oak, I was impressed, and wonder why more people aren't doing it?

Thanks.
 
Ebonizing is a good way to get a dark stain on high tannin woods like oak. It reacts with the tannins and creates a black pigment. It is a different process than what happens in bog oak. The penetration can be shallow to deeper depending on time and if the wood was in a pressure/vacuum tank. The wood is still the same, just darkened to black.

In bog oak ... which can be many woods besides oak ... the submersion in low to zero oxygen water and other anti-bacterial organic compounds in the bog or lake bottom create an environment where the wood does not rot. As it lays there for 100's of years it slowly carbonizes as the lignum breaks down and gets replaced with silica and other minerals. This leaves behind a hard, brittle material that has the cellular/grain structure preserved but the organic structure changed to a mineralized version. As time goes by, the wood changes from the tan color of dead wood to brown in a thousand years or so, and eventually to black by 6000-8000 years. Older wood regularly has silvery streaks of silica that has replaced the lumen and xylem. A hundred thousand more years and it would become petrified completely.

Bonus nerd stuff:
Ebonizing is iron acetate reacting with tannin, which is a phenolic compound, to create an organic dye. The method is identical to making Ferric Chloride, but you use only strong vinegar and steel wool. The acetic acid (vinegar) dissolves the iron and makes iron acetate. If you can get it, 10% glacial acetic acid is great for making iron acetate ... but cleaning white vinegar is just glacial acetic acid diluted to 6%.

IIRC, the same method as ebonizing oak was an old way of making black leather.
 
Last edited:
Crag the Brewer said:
I apologize if this is derailing, but have any of you played with "ebonizing wood" with iron acetate? I'm wondering how This looks like compared to bog oak?
Click to expand...
I've played around with ebonised jarrah, though mostly by burning. i prefer it because you can keep part of the wood red and get some interesting contrasts. it does require more sanding and sealing with oil to remove loose ash
Also means I'm not importing some rare wood with dubious provenance
https://imgur.com/a/HP1z3IW
 
Stacy E. Apelt - Bladesmith said:
I stabilize all my bog oak. From there it works pretty much like ebony.

Use sharp fresh belts and avoid heating the wood. Use slower speeds. Take to a reasonably fine finish (800-1000) and buff lightly ... avoiding heat.

If it is unstabilized,
Use fresh sharp belts and shape gently and slowly to avoid splintering.
Once sanded to the final shape at 400 grit, flood the surface with CA and let dry an hour.
Wipe off the excess with a soft cloth dampened in acetone or nail polish remover. Rub hard while removing the excess.
Let dry overnight.
Re-sand at400 grit and reapply the CA.
Repeat a time or two more if needed.
Sand the last step up to the desired final grit and buff lightly.
Click to expand...
I did this process and I ended up warping it so much that I got gaps and had to re-do complete handles on 2 knives.
 
Were you using it stabilized or unstabilized. Unstabilized has to dry a long time before it can be used. It has been underwater for centuries.
 
I "dyed" an oak handle with solution of ferric chloride and it came out jet black. I was a bit worried about the residual acidity so I rubbed some wet baking soda on it (I didn't want to soak it) , left it to dry for a few days and then I finished with tung oil. I like the end results - no metallic smell, no darkening on the brass elements next to the wood. It's really black but the grain of the oak is still visible.

About the bog oak finish - a guy wanted me to make him a puukko with bog oak and he insisted on not stabilized piece. Made it , finished it up to 360 grit and put some tung oil on it. It had really nice texture and feel to it , not slippery at all. The handle was hidden tang and the guy has no complains so far.

On the other hand he also ordered a full tang knife and he also wanted unstabilized bog oak for scales. I made it , I put g10 liners between the wood and the tang and 2 weeks after it was shipped in Canada from Bulgaria the guy showed me a picture how the scales warped and a gap opened even if they were fixed with corby bolts and glued with good epoxy. Turns out the air is much drier there. Told him to send it back and replaced the scales with micarta.

After this incident I made a hidden tang knife for myself with the same bog oak and I use it for half a year now. There is no movement and I can't feel any shrinkage when I pass my finger on the metal spacers.

I got my bog oak blocks from Ukraine. I don't know if all this provides some useful info but still. I think unstabilized bog oak feels awesome in the hand , I just will not use it on a full tang :)
 
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