Turning Oak Blue

12/05/2014


From original questioner:

You work wood long enough and everything will come up. Here goesó I want to turn Oak blue.

I'm building a table in red oak. I need to stain it iron-tannate blue, very dark at the edges, paler toward the center.

I figure on using iron rich water, and dilute it toward the center or else sand it out some. For the iron-rich water, I put the swarf from my grinding wheel in water. I didn't have a lot, so I washed the soap out of a load of Brillo and dunked it in white vinegar to hasten things.

And there's the rub: I can easily turn the wood gray, because I don't have much iron in the water yet. I'm on a deadline and need to get this done now. Any idea how to make the water richer in iron?

If I sprinkle the iron filings over the table, I know from experience I'll get a lot of little dots of blue. That's not what I want, I need an even, rich color; like if I left an iron knife on wet oak. Unfortunately, I don't have enough knives to lay uniformly over the surface.

Any ideas? I used to have a bucket of rusty water with some nails in it, but threw it out before I got this job.

From contributor JM


Why not get a dye stain?

From contributor Ro


Greetings Jim, I certainly understand being under the pressure of a deadline. Been there myself. Cant you just complete the project using the same formula and finishing steps that you used on your signed off color sample you made prior to starting the project ?

From contributor Ji


I agree with the dye option - check out Lockwood. You can dilute to the intensity you want. I'd make a mixture to the lightest (center) intensity and stain the whole thing with a negative technique. Then make a stronger mixture to shade the edges by fogging on with a spray gun (a positive technique).

From contributor Ni


I agree...dye it. In addition to Jim's idea you could use an air-brush for finer detailing.

From contributor Ji


Thanks for the suggestions, but sometimes you need to do a thing, not do something that may look like the thing.

Turns out there are a lot of web pages about making rust (I didn't think of that search term, but my wife suggested it). Basically, you soak steel wool in the strongest vinegar you can find. In a day or two you have iron acetate, which combines with tannins to make iron tannate, AKA India ink. Apply to oak, wait an hour or a few, and presto! Like magic!

From contributor Ji


Ok

From contributor ri


A lot of steel wool has a slight oil coating. I wash it in lacquer thinner first. I "pre rust" the steel wool before adding it to the vinegar. You get a better solution, faster. You are going to get closer to grey/black instead of blue though, and fading to the center is going to be next to impossible. It will happen almost instantly, no need to wait an hour.

From contributor Je


If you want to really do the thing, why not apply a ferrous sulphate solution to your oak. A more concentrated solution brushed on the outside could be feathered into a more dilute solution towards the middle.

I believe Rubio Monocoat sells it predissolved under the name 'Fumed' but it's pricey. Lockwood carries the crystals for dirt cheap, be careful though because to strong a solution will turn the oak blue-black and it may darken over time, especially under waterbornes.