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Fuming Wood
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Woodworkers Journal image of Fumed Wood“Fuming” is a method of coloring wood by exposing it to ammonia fumes. In short, the wood and ammonia are sealed into a fuming chamber where the concentrated fumes react with the tannin in the wood and cause it to turn anywhere from a rich brown to almost black, depending on the length of exposure. The method became popular around the turn of the century, especially with Arts and Crafts furniture makers, who liked it because it evenly colored the quarter sawn white oak they favored. The process lives on, and is still considered the method of choice for Mission style furniture. And it’s not all that difficult, although there a few important safety considerations. Below, Michael Dresdner explains the process – including how to protect yourself - in answer to a Woodworkers Journal eZine reader’s question.

Q. "Fuming wood. It's a finishing technique used in Mission style furniture. What strength ammonia is required and where to obtain it? Does it require heat and how much heat? How long does the process take, and how much ammonia is required? Does anyone have any ideas for the "Fuming Chamber"?

A. Michael Dresdner: "Fuming is a dangerous process, so gear up with eye protection, respirator, and gloves. Suit up BEFORE you open the jug, or open the chamber. Use 35% solution ammonium hydroxide, which you can get from a chemical supply house or blueprint supplier (this is the ammonia used in blueprint machines -- something becoming increasingly rare thanks to computer plotters.) The ammonia generates fumes that are trapped in a chamber -- hence, very little is required, since a small amount will generate a good bit of fumes. One bowl will do a tented table or chair, and a gallon will do an entire chamber full of furniture. Naturally, it can be used again and again."

"The longer the furniture is in the chamber, the darker it gets. Typical schedules go from 12 hours (a very light fuming) to 72 hours (rather dark). Test scraps first.

"The temperature in the chamber not only affects speed of fuming, but also color. The hotter the chamber, the more reds it brings out. Colder chambers result in a more greenish brown. Make one section of the chamber of clear plastic, and shine a heat lamp into it. Remember, ammonia corrodes aluminum, so no electrical connections should be inside the chamber. You'll notice that when the air inside gets up to 80 or 82 degrees, the reaction goes faster and the colors get slightly redder."

"A simple chamber can be nothing more than a frame draped with clear or black 2 mil plastic. Make the frame of wood scraps or plastic pipe -- anything that will hold up plastic and surround the piece you are fuming. Seal the plastic at the bottom with duct tape. (Obviously, don't fume on a wood floor -- fuming works even through most finishes.) For a more permanent, reusable one, try one of those ubiquitous Rubbermaid storage sheds. Close it and seal up the edges and seams with duct tape."

From the Woodworker's Journal eZine Archives

You’ll also find some great tips on fuming white oak in the Woodweb Knowledge Base. As a bonus, the discussion includes a glimpse of how they did things in the old days:

"There was this old story about fuming my grandfather told about oak and some other woods done in France. He said the work was interior installations of small stores. When the work was complete, everything inside the space was removed, and all windows and doors were sealed except one. This would be sealed from the outside. When it was sealed really tight, the finisher would set a big flat pan of ammonia on a metal grate, and light a real thick candle under it. Next morning he'd come by, check the color, make sure the candle was still lit, and wait for the right tint to the wood. (Ahh… the old tricks--who would care to hand stain an entire architectural molded interior space?)"

(We assume that wood fumers of years past used appropriate, government approved safety equipment as well – of course they did. - ed.)

gustav stickley furniture bookIf you have access to the Fine Woodworking magazine archives (a modest subscription fee is required) make sure you read Kevin Rodel’s "Fuming with Ammonia” (FW # 126). You’ll find a thorough explanation of the process and a look at how fuming works with species other than the traditional white oak. Marc Spagnuolo (aka the Wood Whisperer) offered his wood fuming method recently (see May 14). Note the emphasis, again, on taking the proper safety precautions.

Finally, if you want to learn Mission furniture making from start to finish, pick up a copy of The Furniture of Gustav Stickley. It covers the entire process, including how to fume your finished projects to the point of perfect authenticity.

posted on June 8, 2007 by Rockler
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21 thoughts on “Fuming Wood”

  • Rich

    Fuming of White Oak can be done with "Blue Print" or anhydrous ammonia, 26° be. (I've never heard of 35%.) In a batch that I fumed last week (ambient temperature 54° to 74°) the results were similar to black walnut but with more striations and less of a redish color. The Oak was left in the fumes for about 72 hours. When finished with a BLO, the results are spectacular and most people do not realize that the wood is oak.<br /><br />It would be nice if photos could be added to this blog.<br />

  • blog editor

    Thanks for the comment. We assume that you mean "more photos"? We'll work on that.

  • Gary

    Problem - I was all set to fume an Arts and Crafts oak sideboard made with quarter sawn white oak. All directions I have read say to wet the wood once or twice, possibly adding tannic acid to improve the results, raise the grain, and enhance the fuming penetration. When I wet the wood with distilled water and a clean nylon brush, spots of mildew show up on the wood before it even fully dried. I have noticed this also during glue ups. Analine dyes also require the wetting of the wood. How do I get around this impass? Do I have to go with oil stains? Can I add a bit of bleach to the water or will that effect the tannins?

  • Blog Editor

    Gary,<br />Sorry to hear about the problem, but it doesn't seem like it should happening. To raise grain - as for dewhiskering - you only need to wipe on about as much water as you would stain, and let it dry. In normal humidity, it should dry long before mildew would have a chance to show up.

  • Randy

    After fume finishing white oak, do you put any other finish on it or can you sand it without ruining the finish?

  • Rockler Blog Team
    Rockler Blog Team September 25, 2009 at 9:23 am

    Randy, thanks for the question. You'll want to sand the piece smooth before fuming. Then do a very light sanding with very fine sandpaper after fuming, in preparation for the final finish. You do want to use a clear finish after fuming, since fuming does nothing to protect the wood. Some people like to use a few coats of shellac followed by wax, but other, more durable film finishes could be used as an alternative. It's a good idea to fume a few pieces of scrap (preferably from the same lumber as your project) to use for experimentation. Hope this helps.

  • Peggy

    I am desperate to save my oak entry door and i'm hoping someone can give me some advice on what to do next. My door was originally stained with Watco oil and then finished with marine spar varnish. It held up beautifully until recently. It is partially shielded from the weather by a porch. Only the bottom third needed sanding and restaining in areas . I also lightly sanded the rest of the door. Then I applied the stain and waited 3 days before applying the varnish. It looked really good for 2 days. Then my project was delayed because we had bad weather with rain and humidity and I couldn't figure out why the veins of the wood , particularly where I'd sanded it down more heavily, was turning black and weathered looking. Humidity is usually very low where I live and even though the door never got rained on I guess the constant humidity started to grow mold in the door. That's what someone told me. Meanwhile, I started sanding like crazy because I first thought there was something wrong with my product and I wanted to get all that ugly stuff off. I've done about half the door and then I was told about the mold and that I shouldn't continue doing anything in this weather and I am stumped as to what to do next. How do I protect the part of the door that I sanded to the bare wood?? How do I get rid of the mold? I want to save my door. Someone told me about bleach, but they don't know the details of the amount to apply. Can you please help?

  • Rockler Blog Team
    Rockler Blog Team October 19, 2009 at 1:44 pm

    Peggy - thanks for the comment, and sorry to hear about your trials with the door. It's impossible to say for sure based on a description, but moisture in one form or another probably played a role in the discoloration. Oxalic acid (AKA wood bleach) may help remove the stains. You can order it from us (http://www.rockler.com/product.cfm?page=19462), or you may find it at a local hardware store. There should be instructions on the package and it's not hard to use, but be sure to wear protective clothing. You might want to test it on a small area first. When it comes time to re-varnish the door, be sure to seal the bottom & side edges so that moisture can't wick into the wood and ruin you hard work.

    Hope this helps!

  • Tatskie

    My question is about fumed oak flooring. The project that we are undertaking calls for 2800 sf of fumed 3" white oak floor and oak stair treads to
    match the floor. The way I understand it, the amonia fume penetrates deep into the oak planks during the fuming process. After nailing down the
    fumed floor planks, do we have to sand it in the same manner as we sand a regular oak floor? With the change in color due to fuming, does it mean
    that I don't need to put stain on the oak planks? This is the very first time that we will be doing a fumed oak flooring. I want to make sure that
    I educate myself about fumed oak floor before I begin this project. Thank you in advance for your input. Regards.

  • Rockler Blog Team
    Rockler Blog Team September 27, 2011 at 1:19 pm

    Tatskie. It's true that fuming penetrates into the wood fibers, but unfortunately we can't be the last word on how to proceed. We'd urge you to look for an installer or distributor who has experience and can tell you exactly what to expect.

  • Bob

    I have a 6' x 4' x 18" book case that I would like to fume (Not sure what kind of wood it is). The book case contains four rather large glass doors.
    I believe the glass is antique because it is wavey.
    My question is, if I fume the doors with the glass in them will it discolor the glass?

  • Rockler Blog Team
    Rockler Blog Team November 10, 2011 at 12:27 pm

    Thanks for the question, Bob. Nope - the glass will not be affected. Good luck with the project!

  • Alan Perkin

    Hi, I have done a test fume on some oak wood offcuts before I fume my main pieces of oak, however, after nearly 2 weeks I can still smell the ammonia in the offcuts. Does the smell dissapear after time if left in the open or do you have to do another process to remove the ammonia smell?

  • Rockler Blog Team
    Rockler Blog Team February 17, 2012 at 9:38 am

    Alan - thanks for the question. The odor should dissipate on its own. The time it takes will depend on how strong the fume concentration was and related factors. It's likely that you just need to let it air for a few more days.

  • Tom Hajek

    Can you fume ash?

  • Christine

    Hello! I'm reading can about fuming, because I'd like to darken some new cherry cabinets. The thing is, I don't want to bring out the red, but hopefully change it in the direction of some old cherry cabinets I've stripped & bleached: a gorgeous chocolate brown with creamy grain patterns. It's absolutely beautiful.

    Can cherry be successfully fumed? I've got them sitting in full sun right now, so the process of darkening has started....


  • James Turner

    Fuming can be tricky process. When fuming I've found that you need to include several sample pieces of the wood you're fuming and then periodically pull a piece out, every two hour seems about right. When you pull the sample out put some linseed or tung oil on it to pop the color. When your got the color you want your done. I recently fimed a piece of furniture made with white oak from New York and it took 12 hous to get color I wanted. Last week I fumed a piece with Oregon white oak and it was don in 2 hours, so it pays to include sample pieces tobe pulled out and tested.

  • Mitch McCaw

    One blog mentioned the use of bleach, Be sure not to mix bleach and ammonia. Chloramine gas can be produced which is very toxic!

  • Glenn Auker

    I want to fume oak and ash products that will be used with food, ie,; cheese board, salad bowl type product
    Is it safe to you smoked oak or ash with foods

  • conrad

    I want to fume a whole load of oak beams (French oak) in situ (various ceilings) that are in a building,

    Has anyone done this / can it be done ? Best process ?



  • Bob

    I have a small oak stool that I would like to try fuming, but it is already put together with brass screws. I put a small amount of 28% ammonium hydroxide in a bottle and threw in one of the screws. After a few hours the liquid has changed to a blue color (zinc sulfate, I suppose), but the screw still looks pretty gold and shiny. Is this good enough to say that the screws can probably withstand the fuming? They are just "brass screws" from the local lumberyard, so I have no idea what the zinc content is. Thanks!

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