fuming - revisited

[condeesteso]

This has been on threads before, but some time ago. I was first introduced to this at school by my old woodwork teacher (who was quite old-school then and that was back in the late 60s). I don't see it around much these days, but wanted to test it before considering using it for some components on an heirloom box to be made.
I got some 'ammonia' cleaner from the local hardware store, but then found some open in the cleaning cupboard - Homebase 10%. On a previous thread I had seen that whilst this domestic dilution is slower, it is more controllable - so good for testing and also easy to get (unlike the stronger stuff, I presume).
I wanted to test oak (of course) but also burr oak veneer, and while I was at it, Marcros had told me that fuming cherry was worth a go.
As I was testing small pieces, the tent was a clear plastic bag that came from some packaging (about 2 feet by 1 1/2). A tent pole was a g cramp and a length of scrap, and the base of the bag is sealed down with an array of bits lying around.
TIMING: the process is quite slow (except for the burr veneer) and temperature was low, a few degrees. regardless of temerature though, the ammonia vapour was quickly obvious so I am not sure temperature is a significant variable. The oak and cherry was fully coloured after 3 days but it did take that long. I call fully coloured the point where it seems to not change significantly after that (I actually left it in for 5 days, but saw no visible change after 3).
Here's the oak (I'm guessing European, it's been lying around for years):

Closer on the oak:

The cherry, warmer, a little darker, quite even. I will test a finish on it later (just a light oil):

And finally the burr oak veneer (0.6mm knife-cut):

The veneer was quite dramatic - I'd say as little as half an hour (10% ammonia too)... So I need to retest this to see if mid-tones are achievable. I also need to test the effect of a finish. The idea with the burr was to marry it with bog oak, but I'm not sure yet. I'll flatten and mount it, then try a finish. My suspicion with the burr is the very open end grain everywhere and the thinness of material, hence easy penetration of the vapour. I also suspect the process continues after removal from the tent, so control of the outcome may be quite tricky.

Any other suggestions of woods to test please? I understand it's the presence of acids that causes the effect, so what woods are more acid?

 

[marcros]

Great experiment Douglas.

Beech is said to be worth a go. Also, I have just seen a note about leaving the parts for a few days to let any fumes escape before finishing, and the warning that it can penetrate PU varnish if you stand it on a fl;oor before doing so!

Quite an interesting thread here:

http://www.woodworkingtalk.com/f2/fumin ... wood-6728/

 

[condeesteso]

yes Mark, good thread... but even they can't agree. What I do know is it works with cherry. I may try some chestnut and some elm.
btw, the colour on the burr is unexpected. The oak piece goes darker, but heads towards the grey/green end of dark brown, whereas the burr goes darker but heads towards the red/amber end of brown. So at the moment I don't see it sitting happily with bog oak (very grey/green to my eye). More playing to be done.

 

[marcros]

burr aside, what was the oak like after 24 hours? Was partially fumed an acceptable result, or did it green before it darkened?

 

[condeesteso]

Hi Mark - I'd say the change was unilateral, a bit darker and slight tonal change. I didn't notice that I would get one, then the other. But also 24 hrs was only slight, hardly worth it. Another thought is temperature may be a factor - not in releasing the vapour, but in accelerating the reaction within the wood. Happy with how slow it was though as I am in no rush and fel;t this was very controllable... except for the burr.

 

[tomatwark]

Good test.

I have fumed a lot of Oak on and off over the years, I find that it will look a bit green at first but after a few months it tends to mellow to a nice brown.

I have never done any burr but it maybe that it will stay about the same colour over time and the normal Oak will mellow nearer to it in colour.

I use ammonia from my lacquer supplier so it is a stronger and needs less time.

A good tip is to put a couple of off cuts in the tent so you can monitor the colour change without having to remove the piece of furniture.

And remember the industrial stuff is a lot stronger and you should use a respirator and goggles when using it.

Tom

 

[jimi43]

Interesting indeed Douglas as we briefly spoke about this yesterday.

This could be the solution for the guitar made from British woods thread....fumed oak?

Re your and Tom's comments about concentration....I have a litre of concentrated ammonia...bought from a bootfair along with a load of other finishes...the lady's husband was a furniture restorer...

Unfortunately the ammonia was in an unlabelled plastic container...and you know when you get something the first thing you stupidly do is open the top and have a quick sniff.....

I won't tell you the rest but suffice to say...it took me about 20 minutes to be able to see enough to get a 50p out of my pocket and pay her for the box!

Jim

 

[Eric The Viking]

Unfortunately the ammonia was in an unlabelled plastic container...and you know when you get something the first thing you stupidly do is open the top and have a quick sniff.....

I won't tell you the rest but suffice to say...it took me about 20 minutes to be able to see enough to get a 50p out of my pocket and pay her for the box!

Woo hoo!

I did something similar years back as my dad had a bottle of glacial acetic acid (used as stop bath, IIRC). But ammonia definitely trumps that! Can you smell anything now?



E.

 

[Benchwayze]

Douglas,

Would you normally fume cherry?
Cherry itself darkens with age (Even through a finish) and it doesn't take a lot of aging. I would say I've never heard of it being fumed, but that wouldn't mean very much, as I am no expert on fuming!

Oak of course is one timber I do know is often fumed, but three days to fume seems a long time. I was given too understand that raw oak will take on colour after just a couple of hours. Again, I am no expert.

I like the idea of the process, but my workshop is partially integral with the house, and any kind of fumes soon leak through no matter how careful I am. One reason I never bothered using it as a garage. (I suppose I could find the leak and cure it, but hey-ho! ) :mrgreen:

 

[Tony Spear]

Any other suggestions of woods to test please? I understand it's the presence of acids that causes the effect, so what woods are more acid?

Ammonia (NH3) is very alkaline and Tannin is Acidic (Tannic Acid) so it would seem reasonable to assume that some sort of reaction between those two might well be the source of the colour change and as Oak is high in tannin (the highest in timber, I believe) Oak would exhibit the most effect. Remember that Oak shavings and chippings were highly sought after by Tanneries in years gone by, probably for similar reasons (is cowhide acidic? :? )

For your further experiments, I'm not sure that the acid content is neccessarily the route to follow, but I am told that Chestnut has a pretty high Tannin content.

PS: Another thought, if it is a Tannic Acid/Ammonia reaction, has anybody tried scrubbing an Oak board with an Ammonia solution?

 

[Newbie_Neil]

Hi all,

Sorry, I'm not trying to steal the thread. I hope that this doesn't smell of eggs and grannies, as I thought this might be of interest.

I really like colouring oak by using potassium permanganate as you can turn it a really rich colour. Oak starts to change colour in minutes and the colour is controlled by the amount of potassium permanganate added to COLD water. Using a test piece you can apply a litle of the diluted potassium permanganate. If it's not dark enough just add more potassium permanganate and apply it again.

NB Giving a second coat of the same strength will not make it darker.

Thanks,
Neil

 

[condeesteso]

catching up here! No I would not have thought to try cherry, but for the sake of a scrap why not.
I know 3 days is ages, but I am in no rush at all on this (will be in a few months time... it's a commissioned wedding present) - but I was happy with the predictable rate of change. The table I had made at school was done overnight, but that would be stronger stuff.
I had a hunch that chestnut may be worth a try and I have some bits around. also I will try elm - but as I say just messing about really, it was really the burr veneer I needed to test.
Wiping - yes, tried that too (on the oak) - it darkened but then stopped. There is a deeper tonal range by fuming I feel.
And where do I get potassium permanganate from please? - Also what effect do we get?
I have the burr damp n clamped then I will mount and put a finish on - more pics then, alongside the bog oak to see them paired up.

 

[jimi43]

You get Potassium Permanganate from the chemist in crystals....WEAR GLOVES!!!

Strangely I have some in my shed...but that wouldn't surprise you would it Douglas? 8)

It also makes great volcanoes!!! :mrgreen: :wink:

Jim

 

[Benchwayze]

Douglas:

http://potassiumpermanganate.co.uk/index.html

http://www.norkem.com/en/products/108/p ... anate.html
It's great for controlling Athlete's Foot fungus too. (And what matter a case of Purple feet between friends?)

HTH

 

[dickm]

Never tried potassium permanganate, but pot dichromate does a lovely job on oak.
Don't know what the HazChem status of these things is - according to my chemist/materials scientist daughter, hexavalent chromium, as in the dichromate, is really nasty, but no idea about the permanganate. For an unrelated reason, I needed to check on the toxicity of manganese today, and it is apparently most dangerous if inhaled, so it might be advisable to wear suitable protection if you need to power sand anything after application of permanganate.

And in response to an earlier post, painting 10% ammonia on oak does produce an effect, but also raises the grain which true fuming shouldn't do.

 

[marcros]

Hi all,

Sorry, I'm not trying to steal the thread. I hope that this doesn't smell of eggs and grannies, as I thought this might be of interest.

I really like colouring oak by using potassium permanganate as you can turn it a really rich colour. Oak starts to change colour in minutes and the colour is controlled by the amount of potassium permanganate added to COLD water. Using a test piece you can apply a litle of the diluted potassium permanganate. If it's not dark enough just add more potassium permanganate and apply it again.

NB Giving a second coat of the same strength will not make it darker.

Thanks,
Neil

Neil,

any chance of some pics?

Mark

 

[Benchwayze]

Never tried potassium permanganate, but pot dichromate does a lovely job on oak.
Don't know what the HazChem status of these things is - according to my chemist/materials scientist daughter, hexavalent chromium, as in the dichromate, is really nasty, but no idea about the permanganate. For an unrelated reason, I needed to check on the toxicity of manganese today, and it is apparently most dangerous if inhaled, so it might be advisable to wear suitable protection if you need to power sand anything after application of permanganate.

And in response to an earlier post, painting 10% ammonia on oak does produce an effect, but also raises the grain which true fuming shouldn't do.

I seem to recall having my 'impetigo' spots bathed with Permanganate of Potash by my dear old Mum.

Needless to say 'tis a long while ago, but I am pretty sure it was impetigo. For the younger Forumites, who might not have heard of it, impetigo is/was a variant of Herpes/cold sore; usually breaking out all over one's face. It was considered highly contagious; and probably it still is. Sufferers were quarantined. I.e., a week or so off school! :lol:

Not so these days, so maybe it isn't so contagious after all! :mrgreen:

 

[dickm]

I seem to recall having my 'impetigo' spots bathed with Permanganate of Potash by my dear old Mum.

Also have vague memories of being bathed in it for chicken pox. Certainly used to be/possibly still is used as a gargle for sore throats. But that is the stuff in solution; not sure what happens in the darkening process, but it's possible it releases elemental manganese, hence my caution.
(and while we are on old-fashione ailments, what about ringworm? Very common among those of us who were brought up with cattle)

 

[No skills]

Should anybody be after some chemicals and cant easily get them at the chemists etc have a look at Labpaks website, they are a online lab supplier and will have most things. I have known plenty of people use them, seem pretty reliable.

http://www.prlabs.co.uk/


FWIW

 

[Benchwayze]

I seem to recall having my 'impetigo' spots bathed with Permanganate of Potash by my dear old Mum.

Also have vague memories of being bathed in it for chicken pox. Certainly used to be/possibly still is used as a gargle for sore throats. But that is the stuff in solution; not sure what happens in the darkening process, but it's possible it releases elemental manganese, hence my caution.
(and while we are on old-fashione ailments, what about ringworm? Very common among those of us who were brought up with cattle)

Maybe it was Chicken Pox for me too, come to think on. I am a silly ol' duffer! :mrgreen: