Ammonia Fuming for Mission Finishes
Ammonia in concentrations strong enough to color wood is harsh, dangerous stuff. May 21, 2009
Question
I've spent years searching for the most authentic looking arts and crafts finish for northern white oak. I've had reasonable luck with amber shallacs and Rockler’s mission gel stain. I have yet to try burnt umber or Van Dykes Brown. Anyone out there who feels "giddy" about their mission finish?
Forum Responses
(Finishing Forum)
From contributor N:
I have seen where people build a plastic tent over the items, and then put in a try or ammonia. The ammonia vapor react to the tannen in white oak, darkening it.
From contributor T:
Contributor N is right. The most authentic method would be fuming it in a tent. This is from Gustav Stickley’s own notes on finishing: "In fuming woods, the best results are obtained by shutting the piece into an air-tight box or closet, on the floor of which has been placed a shallow dish containing liquor ammonia (26 percent). The length of time required to fume to a good color depends largely upon the tightness of the compartment, but as a rule forty-eight hours is enough."
From the original questioner:
Thanks. As much as I like the idea of finishing the Stickley way, I guess I'm not quite willing to go there, ammonia vapors and all. My single greatest difficulty is achieving that wonderful patina, and that comes with time that you often find on mission furniture. I think my next step is trying a dewaxed sanding sealer.
From contributor R:
If, as you say you have, spent years looking into how to achieve the most authentic looking arts and crafts finish then how can you not at least try the ammonia treatment? Ammonia vapors are not as bad as you think they are, but after all you haven’t tried it yet.
From contributor Y:
Just remember, if you do fuming, unless all the wood comes from the same log, the effects will be different with each piece of wood. Fuming is dangerous, do outside and wear a good respirator.
From contributor W:
Ammonia in concentrations necessary to stain oak is very dangerous in both its liquid and gaseous states. If it doesn't burn you or suffocate you it will scar your lungs for life. Having said that, fuming does produce a color and color quality that is virtually impossible to duplicate with dyes and/or stains. If you get close, be happy.
From contributor N:
I have seen them tented with a frame with plastic over it sealing the item to be fumed, and then just a tray with about of 1/2" of ammonia placed in the bottom for a few hours. Now this might be impossible for a whole kitchen, but with single pieces I would think you can do it easily and safely. Also, the book I read shows that doing it after you apply a oil finish to the oak will make it turn darker faster, with the wood being near black after eight hours.
From contributor W:
For the record ammonia fuming is a legitimate method of chemically dying wood and was used on lots of A&C furniture. It produces unique colors and looks that are difficult to duplicate with dyes and/or stains. If you have plenty of time you could hang your piece in a hog barn. But if you want to get it done in a reasonable period of time you need an air tight enclosure and some very strong (25%+) ammonia. Do a search on "ammonia msds". You'll find it is very nasty stuff. Using it requires rubber gloves, a respirator with special ammonia cartridges, and eye protection as a minimum. It is poisonous and very caustic with a hazard rating of 3 and a contact rating of 3.
