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NaNO2 safety question

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2 hours ago, Julian Cossmann Cooke said:

So all that swimming I did in the Great Salt Lake while a student?  Not such a great idea?  I did see a bunch of dead birds on the beach...:wacko:

In solution isn't the same as messing with pure, dry powder.  GSL has a range of salinities depending on where you were swimming, but the max is around 27%.  Even the 35% in the Dead Sea is more therapeutic for skin problems than toxic, as long as you don't drink it, and wash it off afterwards.  Drinking sea water in quantity, at only 3.5%, has killed people  Dried salt, OTOH, can cause skin problems, as any ocean sailor (or a geologist stomping around in salt pans) without Chap-stik will have learned at some point.  Pure chemicals can cause a high concentration at the point of contact. :)

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1 hour ago, David Burgess said:

Perhaps those birds were not deceased, but in a deep meditative state? ;)

Joe W., is there some way to know when an oxidizer is "used up"? Would pH be any sort of clue?

To be honest, It gets complex.  And there is only so far I can go before I'll get out of my depth real quickly.   Ph is usually related to acids and bases.   An oxidizer causes something else to lose electrons. They are two different things but can be related.  Oxidation is a very general concept so there are many types of oxidizers and they are all relative.  We may put an oxidizer on wood an it has no effect.  Unlikely but possible.  It depends who is reacting with who.  In college there are whole classes all semester long that just focus on one of these.   I have not taken one of those.

  Acids can act as oxidizers and frequently do.   So in the case of Acids, Ph could be an indicator. But, there are three definitions of what is an acid.  We are most used to a hydrogen donor  H+.   

Also there are other things that oxidize that are not acids and are not oxygen.  Chlorine is more than willing to rip an electron off of something else.  That is why it is so reactive.  It kills people, germs, bleaches flour.   So what is an oxidizer?  It depends.  What is an acid?  It depends. 

 To get to the point, it would be more accurate to identify the exact substance which we are talking about and look up it properties rather than use general term such as acids or oxidizers. That way we know the specific chemical reaction we need to address. The other problem is, wood is a mix of many different substances and we are not sure who the acid, or the oxidizer is reacting with. Maybe a strong oxidizer prefers resin traces and no celluose or hemicelluose is affected.  Who knows?   

 A good easy way to look at it is most oxidative reactions are going to depend on the mass of the two reactants.  In violins, one of my opinions was that the amount of oxidizing or acid agent that could be present is so small compared to the mass of the wood we  are applying on, it does not make sense it would do much damage. In general terms, If we use 1 gram acid and 2500 grams wood, it makes sense there is going to be very little damage to the wood.  That reaction may complete in 1 second or 100 years but the ratio is the same. There is only so much damage that small amount of acid can do. 

 Also, not all acids are the same.  Some are more reactive even though they are the same concentration (molarity).  For instance  you can spray me with 13 molar citric acid or 13 molar hydrochloric acid. I'll take the citric acid any day.     Very different results.   Some react particularly with certain substances.  Sorry, no easy answers.

Then more to consider....

What happens two coatings?  Three?   What percentage of Acid or oxidizer or NaNO3 is needed per gram before there is oxidizer left over?  I have no idea. 

In figuring out what is going to happen........

what specific chemical we talk about is really important.

What concentration is really important

What ratio of reactants is really important

Thanks. 

 

 

 

 

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On 4/16/2019 at 3:47 AM, JacksonMaberry said:

Damn, Joe. Good stuff to think on. Thanks!

Yep, worth saving.

Thanks Joe Wiese, if you have other details to suggest, please do not hold back:)

For example, can I ask if you have some clue on what happens by adding 25% vinegar to the nitrite solution just before application? It's something that had been suggested by Ben Conover in this old thread :  

Sodium Nitirite Questions for tanning maple

By catnip, May 26, 2008 in The Pegbox

~ Ben Conover

At 5% in water then mixed with 25% vinegar and applied over a sealed surface it gives a great colourwhen used with UVA before and after. 
I think it's pretty much what Padding concocted and re-labelled as his primer. 
Regarding what may happen in the future, it's been used for years by some well known makers like Bharat. 
 

 

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4 hours ago, Davide Sora said:

~ Ben Conover

At 5% in water then mixed with 25% vinegar and applied over a sealed surface it gives a great colourwhen used with UVA before and after. 

... over a sealed surface?  Unless this mixture has color of its own, wouldn't it be reacting with the sealer, and not the wood?

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1 hour ago, Don Noon said:

... over a sealed surface?  Unless this mixture has color of its own, wouldn't it be reacting with the sealer, and not the wood?

I think he means a light protein sizing, not a sealer before applying the SN.  A light sizing with gelatin and the SN will still penetrate to the wood. Old Wood does this with their Italian Golden Ground A, which I believe is SN.

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On 4/17/2019 at 5:28 AM, Davide Sora said:

Yep, worth saving.

Thanks Joe Wiese, if you have other details to suggest, please do not hold back:)

For example, can I ask if you have some clue on what happens by adding 25% vinegar to the nitrite solution just before application? It's something that had been suggested by Ben Conover in this old thread :  

Sodium Nitirite Questions for tanning maple

By catnip, May 26, 2008 in The Pegbox

~ Ben Conover

At 5% in water then mixed with 25% vinegar and applied over a sealed surface it gives a great colourwhen used with UVA before and after. 
I think it's pretty much what Padding concocted and re-labelled as his primer. 
Regarding what may happen in the future, it's been used for years by some well known makers like Bharat. 
 

 

Well, I don't know....   Ha ha!  I'm sorry for what I am about to write, it is long but I'll try to be clear and if I make a mistake chemically please be gentle.  I'm trying hard to be clear and correct to the best of my knowledge but this is a lot to keep straight with no mistakes.    I think I have really good idea at the end of this! 

Vinegar is not a pure substance. Besides water is acetic acid  is CH3COOH.   There is other "stuff" in the vinegar which could be reacting with who knows what. There are different types of vinegar.  Vinegar also ages which changes it chemically.  (aged basalmic 30 years yum) But I can give some more insights. 

Vinegar is a weak acid which brings up something I should have explained long ago and forgot. 

A weak acid by definition does not dissociate completely in water. Meaning if we put CH3COOH in water only some of it will turn into CH3COO- and H+.  Only a few of those H+ will be available to go around disrupting other molecules. 

A strong acid like  HNO3 Nitric acid,  will completely dissociate forming a lot of H+ which can do a lot of damage.  That is the reason why people are so weary of Nitric acid and they should be. NaNO3 may produce HNO3 Nitric acid.    It is why I don't use NaNO3 Sodium Nitrate.  I use NaNO2 Sodium Nitrite.  You will see 

Also, before I move on we should know that HNO2 Nitrous acid is considered a weak acid meaning not as many H+ will be floating around.  A lot of the HNO2 is going to stay as HNO2, not doing as much.  NaNO2 may produce HNO2 Nitrous acid.

How strong is strong?  How weak is weak.  There are ways to measure this.  Look below if you want. The numbers at the right refer to the rate that the H+ with dissociate from the -ion.  It is not that important for discussion though.

https://depts.washington.edu/eooptic/links/acidstrength.html

Pause and keep this in mind.   I can take a really strong acid like hydrochloric which everyone has heard of.  I can put a drop in a swimming pool and swim to my hearts content.  That is why concentration matters.   Concentration is NOT the same thing as Strong or Weak.  I believe the concentrations we use are way too small to affect the wood significantly. 

 

To try to take this around to the main topic again, we have to remember we are not talking about putting Nitric acid HNO3, or Nitrous acid HNO2,  on the wood. 

We are talking about putting NaNO3 and NaNO2 on the wood.

The chain of event that will have to happen are this.  I'll use NaNO2 as an example

1. NaNO2 will have to react to water to make HNO2 Nitrous acid.  A weak acid.

2. HNO2 will have to dissociate H+ NO2- . It is weak so not a lot, (relative term) of H+ will react with the wood.

3. We also have to keep in mind that we could put a large concentration of NaNO2 which then has to go through those possibilities to react with the wood which will increase the chance of H+ reacting.

Or we cold put a very weak solution of NaNO2 (in my case 1gr NaNO2 with 100gr of water) and go through those possibilities.  This will produce a lesser chance of H+ reacting with the wood.

Concentration matters. 

That solution is going to dry soon remember and once the water is gone things are going to slow down in general.  

Almost done. 

The vinegar and Nitrite question.  I don't know.  I have some thoughts but the bottom line is I don't know mostly because we have multiple compounds that could be reacting with each other or reacting with secondary compounds.  For instance , an Nitrous NO2 acid produced could be reacting with sugar in the Vinegar and not the wood at all. A sealer was also mentioned.  That complicates things a lot also.  If I find anything out, I'll get back.  Acetic acids is a very very weak acid by the way. 

Last thing, maybe important.   There is a strong community aversion to Nitrate NO3  NaNO3 or KNO3.   These could produce Nitric acid in solution.  How much?  Unknown to me.  I don't know the conversion rates but generally the are once again tied to concentration levels. 

Nitric acid HNO3 is pretty strong.  David Burgess asked about left over oxidation stuff in wood previously.  I did not know the answer.  Here is a theory.

Ages past no one knew about concentrations. Also any biological form these substances will have both Nitrates and Nitrites in them in some percentage.   You can only get it pure from chemical supply for the most part. In ages past, they were using both at the same time.  There probably was other substances mixed in.  My point is unknown concentration.  Unknown purity.

Perhaps......   In the past a person used a high concentration of Nitrates NO3 in wood.  The solution dried pretty quickly.  

The Nitrates NO3 did not have a lot time to convert to HNO3 in the water before it dried.

As a result not a lot of H+ was produced and the wood browned nicely with no damage. They have a nice violin. Out the door.  Forgotten. 

BUT......  there was a lot of NO3 Nitrates left over in the wood.  As decades worn on, slowly humidity provided a little water every day to the nitrates NO3. 

Slowly those Nitrates NO3 converted to HNO3 Nitric acid which dissociated into H+ NO3- and slowly ate the wood away. 

Even the Nitrites NO2 would have an effect but slower.

It is a good idea.  It could be totally wrong though.  I have no proof.  And would explain why people much smarter and experienced than I, are telling us to stay away from Nitrates and Nitrites.   I love and respect you people. 

If someone proves this and writes a paper for the VSA, please give me some credit!  

Last, I still don't believe the concentrations we are using are doing damage.  Please prove me wrong.  I will get a chance to learn something new.  That is all the matters to me.  I don't care right or wrong.

I have to take a break.

 

 

 

 

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Salts of nitrates and nitrites are too dangerous for you guys.  You should stick to coating the wood with horse piss--a much safer substance.  OR use nothing while you sun tan the wood--that works, also.

Mike D.

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20 hours ago, Don Noon said:

... over a sealed surface?  Unless this mixture has color of its own, wouldn't it be reacting with the sealer, and not the wood?

 

19 hours ago, lpr5184 said:

I think he means a light protein sizing, not a sealer before applying the SN.  A light sizing with gelatin and the SN will still penetrate to the wood. Old Wood does this with their Italian Golden Ground A, which I believe is SN.

There is always a lot of confusion about the terminologies used to define these things, also because they are often difficult to classify in a specific category. An illuminating example can be found in the book dedicated to Koen Padding "Violin varnish", where there is a comparison of the terms used in various books (Sacconi, Brandmair etc.) highlighting how everyone uses them with different meanings and associated with different applications or layers. From my point of view a glue-size acts as a sealer, but between the fibers of the wood only without a real sealing effect on the surface, that is without closing the pores creating a smooth and shiny layer above the wood.

Nitrite solutions can penetrate glue-sized surfaces to a superficial level and in any case the proteins react and are colored by the nitrite together with the wood. Of course if nitrite or any other chemical is applied on bare wood the penetration is greater and the effect more dramatic, even too much, always looks almost fake to me.

I think that protein sealers (or sizing if you like:)) ensure a less dramatic and more homogeneous result.

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11 hours ago, Joe Wiese said:

Well, I don't know....   Ha ha!  I'm sorry for what I am about to write, it is long but I'll try to be clear and if I make a mistake chemically please be gentle.  I'm trying hard to be clear and correct to the best of my knowledge but this is a lot to keep straight with no mistakes.    I think I have really good idea at the end of this! 

       ............................

 

I have to take a break

After reading your post I have to take a break too.....:lol:

Thank you so much for your comprehensive answer and for the time you took to write it, really appreciated.  Definitive answers in such complex reactions can easily be given only in a dogmatic way (undesirable, although often typical in the "guild" of makers:)), but trying to understand as much as possible through clear and simplified explanations is always a great help to take some steps towards a better understanding.

I too am quite afraid of the possible long-term problems of these substances, but I am also of the same opinion as you that if you use them with moderation and knowledge, very probably the risks are extremely remote.

However I am still sticking to coloring with UV light, although it is undeniable that this is also a chemical treatment with probable formation of nitric acid compounds involved.

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1 hour ago, Davide Sora said:

However I am still sticking to coloring with UV light, although it is undeniable that this is also a chemical treatment with probable formation of nitric acid compounds involved.

At least the reaction seems to stop when the intense UV light is removed (although I don't know if it stops completely). It seems safer and more predictable though, sort of like using UV to dry varnish rather than adding chemical dryers. I avoid those too, because some sources say they never stop their activity. I figure it's better to be safe than sorry. :)

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4 hours ago, David Burgess said:

At least the reaction seems to stop when the intense UV light is removed (although I don't know if it stops completely). It seems safer and more predictable though, sort of like using UV to dry varnish rather than adding chemical dryers. I avoid those too, because some sources say they never stop their activity. I figure it's better to be safe than sorry. :)

Looks like a bomb-proof strategy.;)

The problem is that when you find some system that seems to work well and safe, sooner or later someone always chime in to claims that it is not good for this or that reason and having no solid basis in chemistry to dispruve, doubts and uncertainties arise.  For example Koen Padding was very much against tanning wood with UV as he wrote in an article now reported on the book.

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4 hours ago, Davide Sora said:

  For example Koen Padding was very much against tanning wood with UV as he wrote in an article now reported on the book.

I'd like to know more about that, and what his objections were.

One form of tanning, using a spark gap to produce ozone, proved problematic. While once all the rage, hardly anyone uses it any more. Could this have been what Padding was talking about?

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2 minutes ago, David Burgess said:

I'd like to more about that, and what his objections were.

One form of tanning, using a spark gap to produce ozone, proved problematic. While once all the rage, hardly anyone uses it any more. Could this have been what Padding was talking about?

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For the record - I don't do this on my instruments. This was for fun with some discarded plates, because the thing was sitting around. The whole chamber fills with an acrid vapor after a few minutes. I nuked these plates thusly for about forty minutes. When they came out, they were slightly dusty and a rather intense yellow with greenish cast. Brushing on a dilute solution of sodium hydroxide instantly transformed the color to a very nice red gold, that could look great under a couple coats of a simple Amber or colophony varnish. One of my shopmates did in fact treat his violin in this way, and it came out looking spectacular. That said, it's possible that in a decade or two it will turn to dust. I'm too chicken. 

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23 minutes ago, Davide Sora said:

:blink::blink:  Impressive!!......and equally disturbing.....:unsure:

Deeply disturbing! I am very interested to see what happens to my shopmates fiddle over time. Looks and sounds lovely now, but is it going to turn into dust? 

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4 hours ago, David Burgess said:

I'd like to more about that, and what his objections were.

One form of tanning, using a spark gap to produce ozone, proved problematic. While once all the rage, hardly anyone uses it any more. Could this have been what Padding was talking about?

I take the liberty of attaching a small extract taken from Koen's article for the part that concerns our topic. Since in the end we are talking about safety, I don't think anyone will be upset but if this were the case I will take it off immediately.

From : VSA Papers - Summer 2007 - Vol.XXI, No.1 (also published on The Strad and on the book "Violin varnish")

Use of Ultraviolet Light Sources

in Lutherie

                                                                           Koen Padding

3 Artificial Tanning of Wood

This writer is not a great fan of coloring wood by means of UV, neither natural nor artificial. Although I do not want to suggest that mild natural (or artificial) sun tanning will already cause objectionable damage; wood that has gone brown by being in the sun for a long time loses some of its elasticity and ultimately becomes quite brittle, to the point of being unusable. To me this demonstrates that tanning is in principle a destructive method that should be practiced with caution. Certainly those makers who contemplate the use of a UVB or C source or a high voltage spark gap for tanning purposes should be aware of the destructive powers and inherent health risks of these “high tech” methods.

         As with the drying of oils, UV light is only a catalyst for the reaction that causes the desired effect. Both of the above methods function on the basis of the formation of ozone, either by the shortwave UV radiation, or by the high voltage electrical discharge. Although UVC radiation from 250 nm down is more efficient at producing ozone, some will already be produced by UVB. The ozone reacts with the nitrogen gas that is present in air to form nitrous oxygen. This very aggressive gas causes the tanning effect, while at the same time rendering the wood very acidic. As is often erroneously assumed, acidity itself is not all that destructive to wood, nor will acidity per se produce a desirable color. (as can be easily verified by coating wood with e.g. strong sulphuric acid)

         Besides forming a strong acid in the wood, nitrous oxygen and shortwave UV trigger the formation of free radicals which pose the real problem of these methods. Free radicals are the cause and result of ageing of all organic tissues and they are their own catalysts. They cannot be neutralized or removed.

Although cosmetic firms will argue that free radicals can be scavenged by vitamins, it is questionable if applying an exotic vegetable juice to the outside of your instrument would have such an effect.

         Some makers argue that they neutralize their wood after ozone treatment with an alkaline solution. Even if acidity was the reason for worry, real life chemistry hardly ever functions like schoolbook examples where acid + alkaline always equals water. Instead of simply restoring the situation back to the untreated wood stage, the effect of this kind of “neutralization” is like that of trying to equalise a mean “right” hook with an unexpected “left” uppercut. While ending up (momentarily) in the same place, you simply got whacked from both sides.

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9 minutes ago, JacksonMaberry said:

Good stuff from a very trustworthy source, thanks Davide!

To those of you who knew Koen or used his Methods, what'd does he suggest for base color rather than tanning? 

His primer.

Some speculate that it was sodium nitrite, but nobody knows for sure as far as I know.

PS I didn't knew Koen, I just know his system

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On 4/18/2019 at 3:26 AM, Davide Sora said:

 From my point of view a glue-size acts as a sealer, but between the fibers of the wood only without a real sealing effect on the surface, that is without closing the pores creating a smooth and shiny layer above the wood.

Nitrite solutions can penetrate glue-sized surfaces to a superficial level and in any case the proteins react and are colored by the nitrite together with the wood. Of course if nitrite or any other chemical is applied on bare wood the penetration is greater and the effect more dramatic, even too much, always looks almost fake to me.

I think that protein sealers (or sizing if you like:)) ensure a less dramatic and more homogeneous result.

Agreed...and depending on the ratio of glue/water the level of penetration will vary. From my point of view.... a sealer does not allow further penetration, ...sizing will allow penetration.

For me I think a very dilute sizing of something is almost mandatory on the spruce top if you want a more homogeneous look. Would you agree?

Do you use a glue size in your work Davide?

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You can see in these video's of Oold Wood's 1700 system that the wood is given a light sizing with gelatin leaf, then the primer (SN?), followed by what I think is some dye stain. I have used this system. If the wood was sealed it would not allow the primer or the color to develop. The sealing comes with the next applications of this system.

This is how I view the difference between sizing and sealing.

 

 

 

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4 hours ago, lpr5184 said:

Agreed...and depending on the ratio of glue/water the level of penetration will vary. From my point of view.... a sealer does not allow further penetration, ...sizing will allow penetration.

For me I think a very dilute sizing of something is almost mandatory on the spruce top if you want a more homogeneous look. Would you agree?

Do you use a glue size in your work Davide?

Agreed.

Before I used the glue size on the top only for the reason you mention, now I put it everywhere for the same reason (I do not like a too dramatic effect on maple flames, look slightly fake to my eyes). I call it "sealer"  to give a concrete contribution to the confusion of the terms, to rise to the level of the other eminent authors of the books and articles:D

It's a sealer with 1 : 25 ratio glue/water so probably it size the wood rather than seal it, but in any case it seal the fibers without filling pores and crevices.

 

In this long version of the video you can see the use of the hot air gun too.

 

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