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Ammonia fuming questions

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Forum topic by eldercop posted 06-16-2015 05:22 PM 1395 views 0 times favorited 5 replies Add to Favorites Watch
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eldercop

58 posts in 974 days


06-16-2015 05:22 PM

Topic tags/keywords: fuming white oak ammonium hydroxide ammonia

Hey all

Made a fuming chamber from an old upright freezer. Had pretty good success fuming white oak using household ammonia. Switching to the 28% stuff, got some questions; Does ammonia lose potency while sitting in the fumer or does it just evaporate. Can I reuse the remaining liquid in another project?

How dark can we go with fuming. Client wants a really, really dark look, but are there are diminishing returns? Will longer exposure always get darker color?

Appreciate any experience here

George

-- "Experience is what you get the day after you needed it" Mark Twain


5 replies so far

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splintergroup

829 posts in 688 days


#1 posted 06-16-2015 08:06 PM

I’ve been fuming for a number of years now and have some experience that may be of use to you.

Your freezer idea is interesting. It would make it easy to get access and you can move shelves around, etc.
I have been using a simple sheet of plastic draped over saw horses with a small muffin fan to circulate the fumes.
One advantage is I can reach under the plastic to pull/add things and I can see the progress without letting my fumes escape. Other than that it is kinda a pain to set up and tear down each time I need to fume.

Household ammonia is a no-go, too weak. I use ‘janitorial strength’ from the local hardware store, I believe it is in the neighborhood of your 28%.
Potency should stay the same, unless you have a leak (which your nose may or may not detect). I usually use a small bowl, maybe 2-3 cups with a fuming volume somewhat less than an upright freezer, maybe 75%. Ammonia is added fresh for each fuming session.

It takes me maybe about 4 hours to get the shade I want which is a medium brown (see my table project) I have tried longer and the results are darker, but there will be a point when all the tannins in the wood (white oak in my case) have all become saturated. A hint of how dark you can go can be seen by placing a scrap directly into ammonia for a minute and letting it air dry.

You can always try some small scrap test samples for various amounts of time to gauge how long to fume.
You should write the fuming time onto each piece as you remove it from your freezer ‘booth’ to keep track for future reference. Of course you will lose a significant amount of your fumes each time you open the door.

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eldercop

58 posts in 974 days


#2 posted 06-16-2015 10:13 PM

Hey Splinter, thanks so much. The dip idea is great. As well as using fresh ammonia each time (dilute it way down to fertilize plants) I probably don’t need circulation unless a supply of “fresh” fumes is required. Did you notice your ammonia evaporating or does it just deplete its strength. This is my first time so you’re saving me tons of time.

-- "Experience is what you get the day after you needed it" Mark Twain

View dhazelton's profile

dhazelton

2325 posts in 1762 days


#3 posted 06-16-2015 11:00 PM

My only advice is get a respirator and keep the freezer out doors.

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longgone

5688 posts in 2774 days


#4 posted 06-17-2015 12:49 AM

These are white oak boxes that I fumed with regular household ammonia from Walmart. The lighter one was fumed for 2 hours and the darker one for about 12 hours. I fumed them in a large Rubbermaid container

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splintergroup

829 posts in 688 days


#5 posted 06-17-2015 01:41 PM



Hey Splinter, thanks so much. The dip idea is great. As well as using fresh ammonia each time (dilute it way down to fertilize plants) I probably don t need circulation unless a supply of “fresh” fumes is required. Did you notice your ammonia evaporating or does it just deplete its strength. This is my first time so you re saving me tons of time.

- eldercop

I don’t really notice the level in the bowl dropping so there is minimal loss due to evaporation. When I was fuming copper (to get a deep blue patina), I needed to fume for several days. I did notice that the rate of patina darkening fell off quickly after the first day and when I replaced the ammonia bowl, the rate picked right up.
Based on this, I assume that the fumes liberate themselves rather easily from the solution and it will need replacing as the strength drops over time. I never reuse the ammonia so this is the only time I’ve had to renew the solution during a fuming.

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