All other ammonia fuming tutorials I had seen recommended using industrial strength blueprint ammonia. But since very few architects use blueprint technology anymore, I figured it would be pretty hard for most woodworkers to find it.
So what is Ammonia Fuming?
For those who aren’t familiar with what ammonia fuming is, it is a chemical method that furniture makers use to darken and bring out the nice figure in certain woods, typically prior to adding a finish.
The furniture is placed in a confined space, and Ammonia, or “Ammonium Hydroxide” is left in a little container for a period of time. The ammonia isn’t applied directly to the wood. The ammonia reacts with the tannins in the wood, and darkens the wood. White oak is the wood of choice for ammonia fuming because this wood has a particularly high tannin content. Quartersawn white oak in particular works nice because ammonia fuming brings out the figure and “ray flecks”.
History of Ammonia Fuming
Ammonia fuming was apparently discovered by accident in England when oak boards stored in horse stables were found to darken considerably when being stored near the fumes from horse urine. Eureka! (Or I guess you could say “Uric-A”…sorry if you don’t get my joke).
The process became especially popular during the late 1800’s Arts & Crafts movement in Britain and the United States. Furniture buyers loved the effect of the ammonia causing the ray flecks in the quartersawn wood to “pop” with contrast.
Ammonia Fuming Safety:
Even though ammonia is a common and readily-available cleaning product, it can be dangerous and very unpleasant to inhale. Because of this hazard, ammonia fuming was discontinued by most large furniture manufactures and replaced with less dangerous methods that mimicked the results. But a lot of modern-day woodworkers have found that they can safely incorporate ammonia fuming if they follow a few safety precautions. So only try this if you accept the risk and use proper safety practices.
You must wear rubber gloves and safety glasses or a face shield, and from personal experience I recommend a mask or respirator mask. And don’t try to open your containers while indoors, as the fumes will make any interior room unbearable within just a few seconds (this was also learned from personal experience of “peeking”).
The Ammonia Fuming Test:
I wanted to see what results I could get fuming white oak without Industrial ammonia (25%-30% concentration), because it’s harder to find, but with ammonia purchased from local hardware stores.
Because I’m fuming test boards and a small stool, I decided to use two air-tight coolers. For bigger pieces of furniture you can build a simple wooden frame “tent” out of scrap wood and wrap it in clear plastic (clear so you can monitor the progress without having to open your tent. I’ve even heard of people renting a small enclosed U-haul trailer for a couple days. I’m not sure how air-tight trailers are, but this is a cleaning chemical, so it shouldn’t cause any problems with the trailer…maybe it’ll sanitize it! But don’t take my word for it…do some more research before trying that.
I purchased an inexpensive bottle of “janitorial strength” ammonia from Ace Hardware, which says that it has 10% ammonia. I put this ammonia in a little plastic container in the blue cooler.
I also purchased a bottle of Ammonia from the cleaning aisle at Lowes. Strangely, the label didn’t specify the ammonia concentration. I suspected they didn’t list the concentration because they were using such a low amount of ammonia. This was later confirmed by my experiment. I put this Lowes brand in the red cooler.
I used two pieces of quartersawn white oak that came from the same board as the Moravian foot stool that I planned to fume. I put painter’s tape around each piece of oak so I could see the difference before and after the fuming. The painter’s tape didn’t fully block the fuming, as I would later learn. I also kept out a bare, unfinished piece of wood as my “control” sample, in case the tape didn’t prevent the ammonia penetration.
Out of curiosity I also experimented with adding my traditional wipe on wax finish (bee’s wax, boiled linseed oil, & turpentine) to the back side of each board and let it penetrate the wood for a couple days, next to a sunny south-facing window, prior to ammonia fuming. If I get enough comments below this blog post requesting a tutorial on making my finish, then I’ll do a video in the near future.
I moved the coolers outside because the fumes are too strong in an enclosed space, especially when opening to check the progress.
I placed a plastic bowl in the bottom of each cooler, and quickly poured maybe 1/2 to 1 cup of Ammonia into each bowl.
I stood the sample boards on end so the ammonia could evenly fume each side, and then I closed the lid tightly. I was careful not to bump the coolers so the sample wouldn’t tip over.
It’s a good idea to place the cooler under a covered area in case of rain. But if you can’t, I’m sure rain can’t get into the cooler. You can also store the coolers in your workshop, as long as you don’t open them indoors…not even for a couple seconds. If you don’t believe me, give it a try and you’ll be running outdoors for a breath of fresh air.
The Ammonia Fuming Results:
I checked the sample boards each day for three days.
My experiment was a success and proved that you can indeed use inexpensive cleaning ammonia from the hardware store to do ammonia fuming. And I discovered that 2-3 days will give the best results with a 10% or less Ammonia concentration. Just make sure you experiment with sample boards beforehand.
The Janitorial strength (10%) Ammonia from Ace Hardware was noticeably darker than the ammonia from Lowes, but the Lowes ammonia seemed to work fairly well too, especially if you don’t want a super dark finish. It all comes down to your preference.
It turned out that the painter’s tape did not totally prevent ammonia fuming, so it’s a good thing that I kept a bare piece of wood aside for comparison.
You’ll notice that the wood has a dull greyish brown look, but a top coat (like shellac or beeswax finish) will change that.
I was astonished to see how stunning the results turned out on the sides of the boards that got the bees wax and sunlight finish prior to fuming. The Janitorial strength Ace Hardware Ammonia turned it a dark coffee brown, almost like Walnut. The Lowes ammonia turned it a nice dark golden amber hue. I liked both results and will likely use both brands of ammonia in the future.
For my Moravian foot stool I decided to go with the janitorial strength ammonia.
I rubbed in my beeswax finish onto the stool and let it darken in the window light for a while. I would recommend at least a couple days, rotating it every once-in-awhile. I got side tracked and let it sit for a few weeks, but turned the stool around every day or two.
I put it in a cooler, added ammonia, and then checked it each day for three days. Here is what the stool looked like just after ammonia fuming and after adding another coat of my wax finish (it looks golden brown because of the sun):
I let it sit in the window for a few days, and this is what it looked like:
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Joshua loves mixing his passion for woodworking with his ability to teach in a simple manner. He lives on a small farm in Earlysville, Virginia with his wife and four children, and builds furniture and teaches woodworking classes in his workshop.