Welcome! Forums General Woodworking Discussions Finishing Ammonia Fumed Oak

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  • #138525
    Steve Giles
    Participant

    Hi.

    Has anyone here tried ammonia-fuming oak? I have read about it but never tried it. The advantage over staining is particularly apparent with quarter-sawn oak where the ammonia achieves a more even colour on the medullary rays. The colour is created when ammonia reacts with tannic acid which is naturally present in the oak. The length of time the process is allowed to run determines the finished shade.

    This technique was common a hundred years ago, but I read somewhere that health and safety concerns when used on an industrial scale made it obsolete. It’s probably also cheaper to use stain than to set up for fuming, but the results are inferior in certain respects.

    Anyway, I’ve always wanted to try fuming oak and would be interested to hear from anyone who has done so.

    Thanks

    #138559
    cbookman
    Participant

    You didn’t mention the color you are trying to achieve, but I’ll throw my $.02 in. I’ve experimented a bit with it, but the results weren’t as dramatic as expected. It will lend an aged look for certain, but isn’t what we were going for at the time, so the project was abandoned. We used a 7 day fume if I remember correctly, and the finished color wasn’t as dark as we were looking for. If you’re looking for a deep brown color, I’d opt for a stain first versus dealing with ammonia.

    Another option is to look at slightly ebonizing the oak, but using a diluted solution. 2-3% iron sulfate in water or ethanol will lend a dark brown/grey cast to the oak. I did this on veneered panels, so it might require a different solution reduction, but anything above 15% will get you a black. You can always add more to get a darker effect. It can be made using white vinegar and steel wool left to soak for 3-5 days. Vent the container to prevent a potential disaster.

    #138638
    Steve Giles
    Participant

    Thanks Christopher for the reply. I don’t have a particular project in mind at the moment (I’m just getting back in to woodworking), but I have wanted to try fuming oak since I first read about the process in relation to American ‘Mission Oak’ furniture about thirty years ago. I guess it’s now or never!

    The fumed oak I have seen has ranged from very dark to a beautiful chestnut colour. Bear in mind that some of these pieces are over a hundred years old though. Maybe different batches (or species) of oak have different tannic acid content, and time also may have had an effect.

    I’m surprised it took seven days to complete the fuming process. I had assumed that it would be an overnight thing. No wonder stain is more popular nowadays.

    Thanks also for the ebonizing tip. That will be interesting to try, but it’s the medium chestnut hue that really appeals to me. I guess I just need to give it a go and see what happens.

    #138653
    cbookman
    Participant

    The 7 days was a pretty rudimentary setup, just a piece of solid oak in a plastic bag with a container of ammonia. Like I said, we weren’t going for that brown you’re seeking, but more of an aged grey look.

    #138799
    cragglerock
    Participant

    I’ve used the vinegar method myself. I just looked around for any rusty iron and threw it in a jar with the vinegar and let it sit for a few days. As Christopher says let it vent otherwise the jar will explode, I just left the lid off completely.

    I found it to pretty effective, I’ve attached an image of a bowl I used it on so you can see. Of course fire works pretty well too but a totally different finish as you can see in the second picture!

    Regards

    Craig

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    #138804
    FrankM
    Participant

    I have never tried fuming but would like to. There are several video’s on YouTube that describe the process. One thing that stuck in my mind is that typical household ammonia is too dilute. They recommended an industrial strength. This makes sense but could be very dangerous. As a chemist I used this strong stuff in a well equipped laboratory but would not be comfortable using it at home in case something went wrong. FWIW.

    #138849
    Steve Giles
    Participant

    Thanks Craig for the pictures. I may give that a go at some point.

    I guess it’s just a case of being careful with the Ammonia. I have used hydrochloric acid to age nickel-plated parts with a fuming method (works brilliantly, BTW), so I have some experience of messing about with dangerous chemicals!

    #139330
    Reno
    Participant

    I have access to strong ammonium hydroxide and other chemicals, but the following process produces useful results for small items:

    Obtain an enameled steel broiler pan. These are the things you cook turkeys in. Pour some household ammonia in the bottom, and put the wood on the wire tray. Put the cover on and heat in the oven at LOW heat. You only need about 140-150° F. Check after 20 minutes.

    Keep a little vinegar in a spray bottle to counteract the ammonia if required.

    #139341
    FrankM
    Participant

    Reno, what happens when you open the oven door? I’m thinking the ammonia vapors could be overpowering. I would not recommend doing this indoors. If you insist, at least put any pets in a safe place.

    #139358
    Reno
    Participant

    Just keep the container closed until it returns to room temperature. The vapor pressure is not high at 140°F.

    #139560
    rudfaden
    Participant

    I have tried it. I used 25% ammonia in a small cup and put the wood in next to it. Depending on the size of the piece, it will take anywhere from 1 to a 3 weeks for the color to change all the way through. The final color will be darker the higher the level of tannin acid is. So if you want it really dark, you should probably use use the ammonia treatment before the wood is dry, as green wood have higher levels of tannin acid.

    25% ammonia smells very unpleasant and can be dangerous. So please be careful.

    Rud

    #139637
    Reno
    Participant

    Red oak yields poor results.

    I’ve read that it’s possible to pre-treat wood with tannic acid before using ammonia. Has anyone yried this?

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