Blackened Oak

[GrahamIreland]

Was just watching Grand designs, aand saw a house use blackened oak on the entry way\hall way.

How do you think this was done - burnt? If so, would there be smell from it, whats the end result like?

Graham

 

[chippy1970]

Just getting it wet is normally enough to turn oak black.


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[ED65]

Wood can be blackened in a host of ways.

Because you can't see this closely it could just be painted! Two or three thinned coats of black paint goes a long way towards producing a very nice 'in the wood' black look, even though it is just a surface coating. Coloured shellac, varnish or lacquer can be used similarly.

Obviously it could be stained too, aniline black dyes can work excellently on a range of timbers. Once you put a film finish over this it doesn't look much different to if you'd just use thinned paint, but if you oil the wood instead you'll see more of a difference.

Because it's oak it could have been chemically blackened by a method now made famous by the Internet, using "iron-infused" vinegar. You can make this just by dissolving clean steel wool in vinegar, sieving it and then painting it on the oak. This reacts with the tannin in the wood, turning it grey through to black depending on the tannin level. So this can be highly variable, but results can be evened out using a tannin solution of some kind.

Last but not least if you have access to sulphuric acid that can be used to blacken wood. I've only seen this in books, never in the flesh, but it looks like it produces a jet black and it's deep in the wood, so the piece can apparently take knocks and scrapes without revealing pale wood as easily as other methods.

 

[GrahamIreland]

Great info, thanks for that.
incidentally I did have a batch of that apple cider vinegar and steel wool on the go, added in a few old nails as well.

Added it to a piece of pine of some sort and it really made it brown. I washed it down a bit with water and it helped bring back a more yellow isn look.

But just experimenting at the moment.

Did coffee granuals as well the other day got a fairly light brown result.

Grham

 

[MIGNAL]

I cooked some oak in the oven a few weeks ago. A lengthy cook it was too. Very dark brown, you would have to literally burn it to turn it black. As it was my attempt turned out a little crumbly, went in the bin. Stains or the ferrous sulphate/acetate solution is really only a surface treatment. it barely penetrates 0.2 of a mm. A lot of pressure might get it deeper. That or being immersed for a few thousand years.
If they used bog oak on that house I suspect the bill would have been very hefty.

 

[marcros]

if it is external, there is a japanese technique for preserving cladding by burning. it is an effect that i fancy trying for a box or similar, but havent got as far as trying it yet.

http://www.shousugiban.co.uk

it can be very textured, or the texture removed so appear flat but still black (i think). there are a few clips on youtube about doing it- one method i saw involved making a triangular length with 3 pieces, and then the fire shot up the middle. it was flipped half way through.
another is this one, similar principle, but it looks a bit more commercially focussed.

https://www.youtube.com/watch?v=rzVoBog8A_4

general search https://www.youtube.com/results?search_ ... u+sugi+ban

 

[GrahamIreland]

I saw the japanese/burning technique before, looks crazy.

I'm thinking it was probably the black stain like ED65 was saying...aniline black dye

 

[HOJ]

I use the propane torch method to scorch Oak, use it to add details to some of the things I make,
there are a lot makers using this technique, I especially like this:

http://www.simonthomaspirie.co.uk/garden.php

 

[ED65]

I cooked some oak in the oven a few weeks ago. A lengthy cook it was too. Very dark brown, you would have to literally burn it to turn it black. As it was my attempt turned out a little crumbly, went in the bin.

Meant to say something about this at the time but got sidetracked: it's possible you didn't need to bin that oak test piece.

When this is done commercially ("torrefied" wood) the baking process dries the wood out far beyond the level of kiln drying and it is apparently very brittle at this point. But it's then rehydrated to bring it back up to something like normal levels, after which it's not quite as bad.

I once over-dried a piece of spalted mystery wood in the microwave and when planing it after you could hear how dry the wood was from the sound, the shavings nearly falling apart on their own. But the wood recovered and the handles that were made from it don't seem weaker than they would have been had I let the wood dry out naturally.

 

[custard]

Scorched Oak is one of the most fashionable finish you can have right now, makers like Marc Fish and Barnsley are currently using the effect for their prestige, exhibition pieces. But none of them use scorching alone. As well as scorching (generally with a chef's blow torch to give the detailed area control necessary to prevent scorching away timber around joints, arrises, and glue lines) they subsequently chemically stain the piece, usually with acetic acid and dissolved steel wool. It's the combination of the two techniques that gives that consistent, ultra deep black.