I'm thinking about trying to fume some white oak. The first project will be a 42x72 dining table.
I have a 5x10, enclosed, water tight utility trailer. I think the trailer may make a great enclosure to fume such a large item. When I'm happy with the color, I can simply leave the doors and roof vents open to purge the air.
Comments? Suggestions?
Barry
That should work fine - but watertight doesn't mean airtight. You may need to tack plastic on the inside to make it air tight.
Put in 2 or 3 pans of ammonia and add a few test blocks so you can remove them and wipe with oil to check the color. The true color won't come out until you put some oil or the like on it.
Thanks!
I was planning on duct taping the back doors and vents, and using the side door to check progress.
Barry
A few other points.
Park it in the sun - the warmer it is, the color leans towards the red end of brown. Cooler and it leans towards green.
If it turns out greener than you wish, hit with some orange shellac to negate the green.
Use a GOOD respirator and goggles when you go in there - a dust mask ain't gonna cut it.
Be sure to use blueprint ammonia as you'll be leaving the table in the trailer for a LONG time with household ammonia.
If the table has leaves, be sure to open the table up and leave spaces between the leaves so all edges, surfaces, etc are exposed to the air.
I've got a really nice 3M dual cartridge respirator that I use while spraying. Didn't think about the goggles, I appreciate the tip.
Barry
I think different cartridges are required for ammonia than for paint solvents.
The filter model I have states that it's useful for ammonia.
Barry
Then buy some new ones of the same model - they have a limited lifespan, and for ammonia you'll be needing them fresh. This is also why storing solvent respirators out in the open is a no-no (for plain dust traps it's not so bad)..
Ammonia is highly water soluble, which is why you need the sealed goggles or full face mask. Any mucous membrane, including eyes, is a magnet for it.
To vent the stuff afterwards you'll be wanting to open the main doors, not just open a window. If the trailer has an aluminium frame, you may also notice a little corrosion beginning.
Personally I might use the trailer as the frame for a fuming tent, but I'd make the tent itself smaller, just big enough to fit around the table and allow air circulation space. The amount of ammonia you need to use depends on this air volume, so you could easily be talking four or five times as much ammonia for a tented vs. untented trailer. It's cheap enough, but it is tiresome to handle.
My experience with fuming white oak indicated that extra time did not darken the wood more, but it did deepen the darkening.
That is, my fuming was done for 2-3 days and the color penetration was at least 1/8" (way more than you would sand through).
When I came up a little short and needed to add a little material to finish off one area, the quickie 6-hour fume brought me to the right color, but sanding revealed a lighter tone.
So, my recomendation would me to leave it a while *longer* after you reach the desired color.
FWIW, I used hosehold ammonia and it appeared to work just fine.
Steve
Thanks. The plan was to stick some test blocks inside, so I'd simply be reaching in to grab one and shutting the side door.
It's a steel frame, but the ceiling has exposed aluminum skin. This is something I hadn't thought of...
Your point about the aluminum corrosion actually has me rethinking the whole idea. The air volume is yet another excellent point. I might be better off with a poly / 1x2 / duct tape containment underneath my deck.
I could tent the table, leaving an access door for the test blocks to be removed.
Thanks Andy! Barry
That may be the difference in the strength of the ammonia. I've left scraps in for 48 hours and they've turned almost black but that's with the 24% or 28% stuff.
Since I do not have easy access to the strong stuff I have no way to test my hypothesis. 2 years of HS chem can only carry me so far.
Ammonia (NH3) is a gas. It is sold in the form of water with the gas in solution.
In a tent, the gas comes out of solution an into the "air". The ammonia gas in the "air" reacts with tannins in the wood to turn the wood dark. I assume that the color change stops when the reactive chemical is the wood is "used up". This is consistent with my imperical observation that most of the color change took place on the surface within 12 hours. There was no significant change after 24 (although I beleive that the reaction was still taking place inside the wood as white oak is only mildly gas permiable.
My hypothesis is that industrial grade ammonia would olny be faster. However that is just a theory.
Personally I'd be really intersted to see a side by side comparison of household vs industrial. It would be nice to know.
Steve
I'll put the household strength on the shopping list and see if I can do a side by side comparison this weekend. There are some extra totes in the basement and I'll cut the test scraps from the same board. I'll try both white oak and red oak.
Well, if you can find a place that does blueprints in your area, they may have a source for "strong ammonia water". Note that this is NASTY stuff to have anywhere near anyone, but does the trick nicely.
Right. NH3 is extremely hygroscopic (or is it hygrophilic?). Anyway, it likes to bond with water, a LOT. But, it'll come back out given the chance.
At some point a balance is reached, not sure which runs out of what first, but yes.
It probably wouldn't get any darker. Assuming you use up tannin before you use up ammonia, the strength just gives you speed vs. control.
I'm sure someone has studied it, but I can't google up anything on it.
try this - a couple of samples of oak from the same board. Gas fume one, treat the other with a light wet coat of the ammonia solution (26% "strong household ammonia" for my technique). The gas fumed oak has a greyish brown colour, the wet-treated oak has a much darker near-black.
So the gas reaction may well proceed to an equilibrium and then stop, but there's clearly a way to force it well beyond this, by applying an aqueous solution. So whatever is limiting the reaction, I don't think it's simply shortage of tannins.
Sounds like a really cool adventure. Would it be helpful if there was a small fan re-circulating the ammonia fumes inside the tent?
What other woods would react favourably?
Cherry reacts beautifully.
Red oak sucks, though - turns kind of a sickly bile-green.
How exactly does cherry react? Will be finishing a table in a few days
-- mission style in cherry... So curious...
I will experiment -- but what did it turn out like for you so I can see if I get similar results when I do a small test piece...
It darkens, rather like it does on exposure to light, but it's not quite the same somehow... fuming seems to produce a richer, deeper color.
Sorry, I seem to have given an incorrect impression. I haven't actually done it myself - one of the other wreckers (David Eisan, I think it was) did an experiment, and posted some photos of his work to abpw six months or a year back. Just gorgeous. It was those photos to which I referred, not my own work.
If you don't like it for fuming, the ammonia is usable for cleaning shellac brushes.
Barry
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