Jump to content

ammonia fuming


H.R.Fisher
 Share

Recommended Posts

  Since in my previous post it was not recommended that I leave a violin in a UV light box for an extended time,I remember hearing about ammonia fuming, I think it is used to darken the wood. Does anyone have experience with this process or know where I could get info.

                                                                                                                                 Thanks  Henry

 

Link to comment
Share on other sites

A technique best left for solid furniture, in your case I would find the brightest room I could and find the "holy" spot where no sun will shine directly on the instrument and simply leave it until you get back, just being exposed to indirect light in a raw state will help move it along, but I would not leave it unattended under lights , if I did I would have the uv light much further away than normal and probably put them on a timer to give the lights a break , just not a big fan of "trusting" lights to not catch fire, that being said I'm sure there are light bulbs that have been on for years

Link to comment
Share on other sites

The following may add to the various comments posted so far.

Around 7 years ago I took a number of treated wood samples into a microscope laboratory at a nearby university.  The photos below are cropped out of shots taken through a microscope capable of up to 500x magnification.  The first features untreated spruce cut in 2013, the second, spruce that has undergone a mild ammonia treatment and the third, spruce that has undergone what I have noted as long term ammonia treatment.  Each end grain face was carefully prepared using a new razor blade typical of those used in laboratories for preparing as crisp as possible detail in such samples.

The increasing lack of crispness with increased duration of ammonia treatment suggests that ammonia treatment does degrade/weaken cell wall structure.  Note cell wall collapse (upper left side) in the third photo.

Bachmann 2013 endgrain 1.jpg

Light NH3 4.jpg

Long term NH3 2.jpg

Link to comment
Share on other sites

13 hours ago, John Harte said:

The following may add to the various comments posted so far.

Around 7 years ago I took a number of treated wood samples into a microscope laboratory at a nearby university.  The photos below are cropped out of shots taken through a microscope capable of up to 500x magnification.  The first features untreated spruce cut in 2013, the second, spruce that has undergone a mild ammonia treatment and the third, spruce that has undergone what I have noted as long term ammonia treatment.  Each end grain face was carefully prepared using a new razor blade typical of those used in laboratories for preparing as crisp as possible detail in such samples.

The increasing lack of crispness with increased duration of ammonia treatment suggests that ammonia treatment does degrade/weaken cell wall structure.  Note cell wall collapse (upper left side) in the third photo.

 

2 hours ago, Jim Bress said:

Great pics John. They definitely tell the story. Thanks for sharing these!

-Jim

Yes, great pictures John, thanks for sharing.

But, to get some clue, it would be useful to see how the wood of ancient instruments looks compared to that of untreated spruce. Not that I want to support ammonia treatment, but I don't think the wood of ancient instruments looks the same as that of untreated spruce. Or maybe yes? I just don't know.

Link to comment
Share on other sites

2 hours ago, pbelin said:

They do tell a story, but what do you make of it?

What I see is that untreated wood cuts cleanly, and the treated wood does not.  Maybe.  Assuming the wood samples started out with exactly the same properties.

I would hesitate to say much more about the result, as how wood cuts with a razor might not correspond too well with properties that matter for the instrument. I have also personally noted that torrefied wood is difficult to slice cleanly on the endgrain, especially if the density is low.  

Also, it would be much more illuminating to see how deep fuming affects radial and tangential wood directions.  I have my doubts that it would get much more than a few cells deep.

Also illuminating would be to get wood from an old instrument and slice it up to see how age affects the visual (and slicing) properties.  Old wood from buildings wouldn't tell you (I have some), as exposure at the surfaces to light and air are likely important.

Link to comment
Share on other sites

1 hour ago, Don Noon said:

I have also personally noted that torrefied wood is difficult to slice cleanly on the endgrain, especially if the density is low.  

The wood that I have been heat treating since 1998 or so* acts differently based on the specifics of how I do it. Done the way I prefer, the wood is actually cleaner cutting than raw.

*(with a zero failure rate so far, and the instruments are more stable than raw wood)

Link to comment
Share on other sites

Thanks for all of the comments regarding the photos.  A few extra comments follow that will no doubt add more confusion...

Paul, ozone treated wood was another that I looked at and have photos of.  I did not consider nitric acid.  At the time I had spruce and maple that I had applied nitric acid to surfaces of but nothing that had been fully immersed in nitric acid.

Don, I agree with your observations and reservations.  All I can say is a relatively clean cut on the end grain face of the untreated Norway spruce sample featured in the first photo was reasonably easy to achieve.  (FWIW, other untreated spruce samples from a different source were similar.)  Mild ammonia treatment resulted in increased difficulty in achieving a clean cut with some tearing being evident.  Longer term ammonia treatment resulted in even more difficulty.  During the cutting process some cell walls crumbled or collapsed.  I used fresh blades in each case and did my very best to create as clean as possible endgrain surfaces.  This involved using a slicing as opposed to pushed cut which I did vary depending on the inherent nature of the sample involved.  Some samples were quite brittle, others more crumbly, some firm, some soft and soapy etc., etc..  A clean as possible cut was my primary goal for the reason mentioned below.

Michael, I also looked at spruce samples that had been heat treated in various ways.  In some cases the end grain cut achieved was very clean and crisp and in others, not so.

Davide and Don, my somewhat misguided original intention was to look at cell wall detail in various treated samples and compare the detail to that in old wood.  Don, like you I had some old spruce from buildings.  (I think yours, like mine, is a dendro match to certain Cremonese instruments???)  I also had spruce taken out of an old German piano.  I felt that SEM would likely provide a means of seeing what remained intact versus degraded within cell wall layering which in turn could provide some indication of whether lignin, hemicellulose or cellulose had been impacted.  (Note diagram below.)  The initial step involved preparing end grain surfaces and viewing the various samples under a stereo microscope.  It was immediately evident that the end grain in most samples was not cleanly enough cut to guarantee seeing the cell wall layering detail that I had hoped for.  At that stage I forgot about SEM and decided that all I could do was to take photos of the cut detail through a more powerful stereo microscope.  As to what these photos actually mean – I suppose that in a very loose way they may suggest that some treatments seem to impact cell wall integrity/strength/resilience more than others....

 

Micrograph of a softwood.jpg

Link to comment
Share on other sites

Still interested in the chemistry of this reaction. Several people have said the reaction continues for a long time after exposure. Is this really true? One would think the available ammonia would react with other chemicals but that when no more ammonia is available the reaction would stop. While I (and Michael D) am certainly aware of deleterious effects of strong acid fuming due to seeing the results of a short period of work by one of our mentors, I am less convinced that a relatively mild base would do as much damage. Certainly the use of oxidizers of all kinds especially to darken repair wood is almost ubiquitous. Does the reaction of these various chemicals also continue for a long time?

Link to comment
Share on other sites

I suppose most of us have tried some not so recommended chemicals but it's hard when you start :

You're told that

-ammonia makes the wood cardboard like. - Nitrites are so higroscopic they create huge problems.

-Nitric acid reacts for ever, makes the wood crumble and bleaches the purfling. 

-any sort of heat treatment just destroys everything

-a friend told me he now avoids UV because he feels it damages the wood too

-don't think of using oil directly onto the wood! 

-if you don't get rid of the acidity of the rosin you're in for big trouble. 

 

All that only after 20 years of course, so you're only gonna be able to see for yourself once it's too late. 

So what does a young maker have left, if he/she doesn't want to varnish on white wood? 

Link to comment
Share on other sites

59 minutes ago, pbelin said:

I suppose most of us have tried some not so recommended chemicals but it's hard when you start :

You're told that

-ammonia makes the wood cardboard like. - Nitrites are so higroscopic they create huge problems.

-Nitric acid reacts for ever, makes the wood crumble and bleaches the purfling. 

-any sort of heat treatment just destroys everything

-a friend told me he now avoids UV because he feels it damages the wood too

-don't think of using oil directly onto the wood! 

-if you don't get rid of the acidity of the rosin you're in for big trouble. 

 

All that only after 20 years of course, so you're only gonna be able to see for yourself once it's too late. 

So what does a young maker have left, if he/she doesn't want to varnish on white wood? 

:lol:

Use common sense and take your own risks.:)
Consider that even those who support more or less reliable theories do not know everything deeply and only try to give their impressions and opinions based on their experience and feelings, no scientific dogma. Personally I think that trying only things that might have made sense even in the 1600/1700 would be a good line of thinking.

Link to comment
Share on other sites

5 hours ago, pbelin said:

So what does a young maker have left, if he/she doesn't want to varnish on white wood? 

I think it is about the least harmful procedure. 
I love the hygroscopic debate about nitrates. On a whole violin it is about 0,3 g pure nitrite salt needed… 

Using casein can also be a lot more harmful than the methods you named.

It is all about the execution of a procedure and not that much about the procedure itself.
 

 

Link to comment
Share on other sites

2 hours ago, Michael Szyper said:

thank you @John Harte for this great post. I was tempted to do a bit of fuming but this is quite discouraging. Did you by any chance similar tests with nitrites? 

No.  My focus at that stage was more related to possible full wood treatments and their effects; i.e., various forms of full immersion soaking (long term water, borax solution, boiling), fuming (ammonia, ozone) and heating/baking.

I have tried nitrites (Na and K) but only in the context of trying options that could colour/stain/darken wood surfaces.

Link to comment
Share on other sites

10 hours ago, nathan slobodkin said:

Still interested in the chemistry of this reaction. Several people have said the reaction continues for a long time after exposure. Is this really true? One would think the available ammonia would react with other chemicals but that when no more ammonia is available the reaction would stop. While I (and Michael D) am certainly aware of deleterious effects of strong acid fuming due to seeing the results of a short period of work by one of our mentors, I am less convinced that a relatively mild base would do as much damage. Certainly the use of oxidizers of all kinds especially to darken repair wood is almost ubiquitous. Does the reaction of these various chemicals also continue for a long time?

This may be of partial interest: https://heritagesciencejournal.springeropen.com/articles/10.1186/s40494-022-00718-1

Also note the Supplementary Information.

Without reading this again I can't tell you whether there is any discussion of full reaction time. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.


×
×
  • Create New...