Ammonia and Oak

[DigitalM]

I've just been watching a Simon James DVD where he talks about fumigating oak with ammonia to darken it. Well that would suit a couple of projects I've got going on right now, so I run off to amazon only to find various "power cleaners with ammonia" and ebay, only to find similar results. I thought at first it was just regular household bleach but a quick look on wikipedia seems to suggest otherwise.

So just wondering, not having used it before ...

[1] If you pour out a small tub full (250ml perhaps) and whack it in a sealed bag with your oak (as Simon James suggests) does that totally evaporate? I've no idea how volatile the stuff is.
[2] Do you need to use a particularly strong mix? Or will virtually any % of ammonia do and it's just a question of how long it takes?

Any other salient info also appreciated.

 

[swb58]

I'm new to Fumed Oak too, only looked it up recently because of a one act play of the same name.
My understanding was that the oak was kept in the fumes of the ammonia, presumably the higher the concentration the quicker the effect.. Would be interested to hear what you find out.

 

[DigitalM]

I'm new to Fumed Oak too, only looked it up recently because of a one act play of the same name.
My understanding was that the oak was kept in the fumes of the ammonia, presumably the higher the concentration the quicker the effect.. Would be interested to hear what you find out.

Yes, I assume as much too, but there may be a dilution beyond it just isn't worth the waiting time!

 

[marcros]

I am about to do a bit of fuming actually. It has been a while since I did any, so this is from memory.

I bought some "household ammonia" from a hardware shop.None of the supermarkets stocked any. It is not bleach- I suspect that the supermarkets don't keep it because if mixed with bleach it will produce chlorine gas (from memory).

I haven't seen the dvd so this may be telling you what you know.

It is volatile, in that it stinks! it gets airborne pretty easily in the summer, but at the moment may take longer. it is nasty stuff, so you don't want to be breathing it in, and take the usual precautions that you would with chemicals- goggles, gloves etc. It is comparable with strong bleach in its nastiness, so you are not going to dissolve your feet! From memory, it doesn't all evaporate, and you end up chucking some away at the end. I dilute it heavily and chuck it on the compost heap or tip it back in the bottle. I used about 1cm in a takeaway container for a tv stand made from new "sleepers". 100ml maybe?

I didn't look at the strength of the stuff I bought, but it was household, rather than industrial, or lab strength.

You really need to have some sample pieces in with the project. Take one out every hour (in the summer) and test the colour. It will look like nothing out of the fuming tent, so you need to put the finish you are planning to use on top of it. It will go from dull green grey to a shade of brown. For a darker brown, leave it in for longer. They say that it can go almost black, but I have not found this- a very dark brown yes, but still clearly brown rather than black. I made a clock once using 12 different shades of fumed oak. It took 24 hours for the 12 o'clock, and you could see the difference between the numbers at 2 hour fuming intervals. I can't find the pic now, sadly.

Do it outside or at least not in the house. The fuming tent can be as simple as you like. I have use the wheelie bin laid on its side before, and also some plastic sheets on other occasions. It cannot have metal in it- put the ammonia into plastic or glass. I normally use a plastic takeaway tub. The fumes need to see the workpiece. If you rest it on 2 bearers, you will get 2 untreated stripes. This may be ok if there re parts that won't be seen.

 

[Mike Jordan]

I've fumed some oak to try the effect in the past. I used ammonia purchased from the local chemists shop and put a small tray in a plastic bag with the oak, the bag was left in the back of my van on a warm day for quite a short period. The result was a muddy brown colour which didn't seem to me to enhance the oak.
If you intend to have a try I recommend that you experiment before doing anything that matters!
The question has been asked before and a search should help your quest for information.

 

[ED65]

There's quite a bit on this in the forum archives so as mentioned well worth doing a search to read more.

[1] If you pour out a small tub full (250ml perhaps) and whack it in a sealed bag with your oak (as Simon James suggests) does that totally evaporate? I've no idea how volatile the stuff is.

The evaporation rate is somewhat like that of water, so you wouldn't expect it to vanish in a sealed container over a short period.

[2] Do you need to use a particularly strong mix? Or will virtually any % of ammonia do and it's just a question of how long it takes?

For fuming the ammonia was traditionally very strong. Normal 'household' ammonias aren't even close to the same concentration (a quarter or less). They will still work however, only much more slowly.

The strength you're supposed to use for this purpose is actually a bit hazardous, not merely noxious, and it's considered vital to either work outdoors or wear a respirator. Or as some do, both! So it's actually much more pleasant to work with household strength.

Although some frown on the practice in addition to fuming with it you can apply it directly to the wood, and household ammonia is an ideal strength for this. You can apply more than one coat to get the desired colour, just like with a vinegar/steel solution which is another chemical-reaction stain.

It's well worth raising the grain beforehand and knocking back before fuming, and vital if wiping the ammonia on.

Last thing, if you do a test run remember to apply finish to the test piece(s)! The colour is changed dramatically once finish is applied.

 

[custard]

Any other salient info also appreciated.

Before investing a shed load of effort be aware that fumed Oak is about as fashionable as kipper ties, even though fuming other timbers like Eucalyptus or Pear is very on trend. Part of the reason fumed Oak gets the thumbs down is that Oak is a fairly cool toned timber to begin with, and fuming makes it colder still; so as well as darkening your project it also makes it look a bit weird, at least to a modern eye.

Whenever I've fumed I've used .880 ammonia, which is horrible stuff but it gets the job done without patchiness. But working outside isn't necessarily the answer because you might well gas the neighbours when you open up the fuming tent!

If you're determined to experiment with novel finishes try something like two pack bleach, scorching/ebonising, or soap finishes. Seriously, ammonia fuming is just a load of work for a very iffy return.

 

[yorkshirepudding]

I have used ammonia to fume an oak goblet I had turned. Being only 6” or so high I stood it in a Tupperware lidded container on an inverted glass to raise it above the one inch or so of ammonia I poured in before fitting the lid. After a couple of days the goblet was very dark and had the appearance of a medieval artefact.
The ammonia I used was industrial strength and came from a friend who worked in the chemicals industry. Protection was worn throughout.

 

[DigitalM]

Any other salient info also appreciated.

Before investing a shed load of effort be aware that fumed Oak is about as fashionable as kipper ties, even though fuming other timbers like Eucalyptus or Pear is very on trend. Part of the reason fumed Oak gets the thumbs down is that Oak is a fairly cool toned timber to begin with, and fuming makes it colder still; so as well as darkening your project it also makes it look a bit weird, at least to a modern eye.

Whenever I've fumed I've used .880 ammonia, which is horrible stuff but it gets the job done without patchiness. But working outside isn't necessarily the answer because you might well gas the neighbours when you open up the fuming tent!

If you're determined to experiment with novel finishes try something like two pack bleach, scorching/ebonising, or soap finishes. Seriously, ammonia fuming is just a load of work for a very iffy return.

Well I think it's got to be tried once. I'll leave it in the hands of the gods - if the local hardware shop in town (2 min walk) has some ammonia, and it's a reasonable price, I'll give it a go.

 

[DigitalM]

Do it outside or at least not in the house. The fuming tent can be as simple as you like. I have use the wheelie bin laid on its side before, and also some plastic sheets on other occasions. It cannot have metal in it- put the ammonia into plastic or glass. I normally use a plastic takeaway tub. The fumes need to see the workpiece. If you rest it on 2 bearers, you will get 2 untreated stripes. This may be ok if there re parts that won't be seen.

This is great, it means I get to have a takeaway too. So, you don't seem as cold on the idea as custard - you've had acceptable results?

 

[woodbrains]

Hello,

I did it once years ago. The stuff to ask for is '.880 ammonia'. It is very corrosive and will kill your lungs if you get a whiff. Outdoors only, in a polythene tent. Pour it into a shallow glass dish to allow easy evaporation into the tent. Place several offcuts into the tent, along with the piece to be fumed. Take a piece out every 1/2 hour to see how the colour is progressing. Stop when you are happy with the colour.

As a side note, it is best if the piece to be fumed is made from oak from the same tree. IMHO it is essential that this is the case. Otherwise, the colour will take markedly different on the different oaks with different tannin content and the job could look like a dog's dinner.

Mike.

 

[ED65]

Re. the final colour and the difference the finish makes thought this might be worth posting:

:shock: no? This is with oil which as always makes for the biggest colour change, expect similar to slightly less with varnish, much less with lighter shades of shellac and little difference with water-bourne finishes and lacquer.

And just as with the vinegar/steel solutions the effect is entirely dependent on the initial tannic acid content of the wood. Some oak is surprisingly light in tannic acid, some very high, and it can vary board to board.

 

[DigitalM]

Well I think it's got to be tried once. I'll leave it in the hands of the gods - if the local hardware shop in town (2 min walk) has some ammonia, and it's a reasonable price, I'll give it a go.

And the Gods have sent me a shining bat-signal of go-ahead approval in the form of a cheapo bottle of 9.9% ammonia at the local hardware shop for £2.50. And yes they made jokes about me buying it for nefarious reasons, although to my knowledge no-one buys the stuff to get high on.

It put me in mind of when, years ago, I went into a chemists to buy iso-propanol. Fearing I might drink it, no doubt because of the mad-pirate-glint in my eye, they said "and what's will you be wanting that there IPA for then me laddo?!".

"For cleaning the heads on my cassette deck" I reply innocently enough.

Barely satisfied, and still a bit miffed at now probably having to decant some of their precious supply to some oic off the street, they ask "How much do you need?".

To which I reply "A pint please" and instantly realise that I may as well have chuffin' followed up with "and a packet of salt and vinegar crisps, oh, and a pickled egg!".

Now, of course, I awaiting the door to be kicked in by the anti-terror police, to see what I want ammonia for...

 

[Steve Maskery]

All sound above.
Just for the record:
Ammonia is a gas, NH3, and it stinks. Think Grandma's smelling salts. It disolves in water, and when it does so, the solution becomes less dense. "Lighter" in common parlance, but the correct term is less dense. The more the gas dissolves, the less dense the liquid becomes. When no more ammonia will dissolve in the water, it is called saturated, and at that point the liquid is only 88% as dense as water, and is is called .880 ammonia solution. It doesn't get any stronger.

When it is exposed to the air, the gas evaporates, the remaining liquid gets denser, back to becoming water, until the ammonia has evaporated and the water remains.

Ammonia solution at only 10% will still have a darkening effect on tannin-high woods, like oak, but it will take longer, because the solution itself is weaker, it contains less ammonia in the first place.

It's some time since I have fumed oak, but I have a couple of projects in the pipeline which I intend to fume. The great advantage of fuming over a bottle of stain is that the colour change happens at a cellular level, so you don't get the problem of end-grain soaking up all this brown stuff and looking darker than its side-grain brothers.

Fumed oak may not be fashionable, but then neither am I, so I intend to do it again anyway!

Steve, B.Sc. Chemistry (Hons), 1979. God, that was a long time ago.

 

[Fitzroy]

Nefarious reasons. If you mix ammonia solution with iodine crystals you make nitrogen tri-iodide, a black gunk that’s a contact explosive when dry. Much fun had making it as a teenager with supplies surreptitiously added to the order list at my father’s pharmacy.

F.

 

[Racers]

Steve, I still have that bottle of ammonia when you are ready for it.


Pete

 

[custard]

The great advantage of fuming over a bottle of stain is that the colour change happens at a cellular level, so you don't get the problem of end-grain soaking up all this brown stuff and looking darker than its side-grain brothers.

Excellent point!

There is though another option for minimising end grain darkening, which is to sand the end grain to unfeasibly high grits, i.e. over 1500. I make a hall table/matching mirror set which has legs that protrude through the top, and I don't want the visible end grain to be materially darker.

You can see in close up that the end grain in the tops of the legs (high grit sanded) is much lighter than the end grain in edge of the drawer (normally sanded, i.e. 240 grit).

The advantage of this method versus fuming is that if you use an oil based finish it will darken the end grain of fumed timber, where as with high grit sanding it won't.

 

[custard]

By the way, for fuming with weaker grades of Ammonia it might be a good idea to pre-treat the workpiece with tannin, i.e. strong tea, ground up Oak galls etc.

 

[DigitalM]

Only just got round to this, but my goodness, the reek. My test piece looks "damp" and utterly stinks. How long does that last?