Try ebonizing with an aged solution of steel wool in vinegar.

The article below goes into detail. You may not need the "tea" method as oak has natural tannins.

You should do some trials to get the exact look you are wanting.

Here is a link that might be useful: Ebonizing

Thank you very much for the answer, I read the article, really very helpful.But I want to ask how can I do this mixing effect with all the colors between grey and black. No just to make all plank black. Thank you again for the answer.

You get the variable effect by using a weaker solution of vinegar and iron so it doesn't completely react. And rubbing a bit off, if you want.

To get the really black color usually requires added tannins, even to oak. The darkest I got with oak was a deep purple-gray.

It's easiest to make a strong solution and dilute it. One or two pads of steel wool in a liter of household vinegar gives you a reproducible solution. Wash the steel wool in soapy water because it is often oiled to prevent rust, then stuff it into the bottle of vinegar and leave the lid loose until the steel is dissolved.

Then start testing it ... wipe on full strength and see what happens. If it's too dark, dilute it 50:50 with water and test again.

You MUST TEST on the wood you will be using for the finished piece. I got results from pale brown to deep grey with the same solution, because the wood varied in tannins.

Lazygardens is correct,

Wood Finishing rule #1

- If this is not your first time using a new product or process, test and trial on scrap, not your project.

In other words, avoid "Ready, fire, aim."

Thank you for the answers , i already put the steel wool in vinegar :)

You could try black wax. Is very black in color but transparent finish. More coats = darker.
Casey

I I want to ask where can i find this "tea" for the the "tea" method ?

I forgot to mention the other technique often used to ebonize -- use India Ink as a stain. This is available at art supply stores.

http://www.woodworkingtalk.com/f8/ebonized-poplar-india-ink-best-finish-would-14986/

Here is a link that might be useful: bark tea source

Norway?

The tea most people use is ordinary black China tea ... the kind you drink. It is high in tannins. Brew a very strong black tea from the cheapest possible tea leaves and paint it on the wood to increase the tannin content.

The "bark tea" is quebracho: the extract of a South American tree bark used for leather tanning and in taxidermy. You might find a similar product made from oak bark or other tree products in Europe.

You might be able to use black fabric dye, or an ebony stain.

I bought a pound of powdered quebracho extract - if the China Tea does not work well enough, and you can't find a good European source, I am willing to send you half an ounce of quebracho by mail if you won't get in trouble with Norwegian customs. That would be enough for many ship models. Click on my profile and send an e-mail message.

Try some black shoe polish.
Not the liquid type, but the wax type in the small tin.

Another source of black is to use asphaltum (a type of oil tar) thinned with paint thinner.

This post was edited by brickeyee on Wed, May 22, 13 at 10:27

asphaltum, in my experience, gives a more brown-ish color. It's often used in oil-based stains and danish oils as their "walnut" offering. I used some Deftoil Dark Walnut years ago that was pretty black, but it did not have the variation in gray tones that OP is looking for.