Aged oak, blackened oak

[Prashun Patel]

Thought this might be of interest to people looking to achieve an darkened look on oak without using ammonia, traditional dye, or steel wool and vinegar.

Each of these has their place, but also their own downsides. Here is another arrow for your quiver:

Sodium nitrite.

It is easily obtainable online and mixes easily and in my experience, innocuously with water. It is used to distinguish between red oak and white oak.

The ratio is forgiving and not critical. But about 10% is what I've been using.

It turns white oak black, and red oak a dark brown. On white oak, it dries to a silvery, almost green / mettallic color. It blackens with a top coat.

Anyway, it's cheap and effective, and novel (to me).

YMMV.

[Jamie Buxton]

When you use a stain that's mostly water, what is the finishing process? You apply the stain, which colors the wood, and it also raises the grain. What's next? Can you sand enough to fix the grain-raising, but not so much that you go through the color layer? Or do you just have to live with a rough surface?

[Prashun Patel]

That's actually the great thing about this chemical process. The reaction penetrates deeper than does a stain, so there is less risk of sanding through.

The other thing to note is that there are other tricks to be played to stymie grain raising. Contrary to popular practice, I like to sand my wood to a much higher grit before finishing. The piece in my pic has been sanded up to 600 grit. Despite having soaked this piece in the water/sodiumnitrite solution, the raising has been minimal. It takes only a light buffing with 600 grit to restore it back to it's pre-bath softness.

Also, unlike a stain that can be inhibited by burnishing the surface, it appears that the chemical reaction is less inhibited by higher grit sanding.

Now, I'm not saying you need to alter a normal finishing regimen. You could easily sand to whatever grit you are comfortable doing, brush on the solution, and then re-sand with your highest grit, and you'll be fine.

As to how much you need to put on, I advise to brush it on with a foam brush, then wait for 10 minutes and reapply if you need more color/depth. The reaction takes several minutes to reach maximum color.

[John TenEyck]

That's interesting. Got any pics after finishing?

John

[Prashun Patel]

So, here is the bowl after about a week. It's topcoated in shellac.

You can see that the black has actually gone away and instead it has turned a dark shade of brown. There are some green tones remaining in it.

This bowl went from black, to army green, to brown.

It was weird and alien. So, I wouldn't characterize it so much as 'aging' as it is just a novel kind of dyeing.

Anyway, YMMV, but I thought this was a fun experiment that I will try again.

[John TenEyck]

Thanks. That big color shift from dyed to finished rules it out for me.

John

[Prashun Patel]

And I'm not sure it won't continue to shift. I'll post more pix in a few weeks.

[Allan Speers]

FWIW,

several top violin luthiers (I mean the very top guys) use sodium nitrite in their ground. That is, the initial part of their finishing schedule, used to pop the grain (typically on Maple) and seal the pores. Obviously, the SN is used for the first part.
According to my notes, this is followed by exposure to strong UV light for a while. (I'm not sure why)

It's often then followed by french polishing, before the final varnish.


Also, of course, the application of sodium nitrite is a foolproof way to differentiate White Oak from Red Oak.