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Discussion Starter #1
Do you seal the edge with lacquer (or shellac, wax, etc.), or do you leave it raw? Thanks.
 

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Left as raw material. Not advised to put anything on it as it could cause pad sticking.
 

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If you lower it down till the body (like on this gif)... you surely won't need to apply anything on the tonehole rim.


 

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When the tone holes are gone, the sax is finished. I typically forbid any abrasives to be used on the sax anywhere.
 

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The above video freaked me out until I saw that it was a video loop. The horn looked to be ruined and yet the culprit continued? The stuff of nightmares.

Raw brass reacts with wet leather. If the leather is wet, the deterioration can be fast. Lower humidity does the same, but verdigris will be produced over a long period. It will produce "little chunks of stuff" (my scientific terminology) that will stick in the pad seats. Check out this blog for more info. I've tried a couple of things to seal the raw brass. Wiping with tung oil works, but it take the tung oil more than a week to polymerize (solidify or "dry"), which is a pain to wait during a repad. I've since started using selenic acid, which puts a forced corrosion on the raw brass. You can get it in a "touch up pen" at most sporting goods stores. It is used to touch up the bluing on firearms. You can run the pen around each tone hole chimney a few times and then return with a wet cloth and wipe off any residual. It can't be seen as it simply turns the rim a slightly brown color. I've had no corrosion on tone hole chimneys on my alto that I repadded 14 years ago.

Mark
 

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Discussion Starter #6
Raw brass reacts with wet leather. If the leather is wet, the deterioration can be fast.
That's precisely what I was concerned about. Thanks for the link. Great website, by the way. Where do you buy selenic acid? Or do you use some product based on it? Thanks.
 

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It is a non issue in my experience. If the tonehole is cleaned occasionally with naptha, and/or a few passes of 1000 grit sandpaper, the bare brass will not be a problem. Of more concern after leveling toneholes is to remove any burrs around the edges.
 

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carolus;3809726Where do you buy selenic acid? Or do you use some product based on it? Thanks.[/QUOTE said:
This Birchwood Casey bluing pen is what you can find at sporting goods stores that sell fire arms. Here is a video showing how it works on steel.

https://www.youtube.com/watch?v=TtDt89VZleg

In the video, the bluing pen appears to turn steel black rather than "bluing." The black film tends to lighten up when cleaned with gun oil and leaves more of a blue tone (on steel). The alloy and the acid determine the effect, that's why some use steel bluing concoctions made of a variety of acids. The same is true with turning brass different shades. Since the color isn't important on a brass tone hole rim, the mixture in the bluing pen works for creating a corrosion resistant finish. With the cap back on the pen, it is good for years (and other projects).

Some may never see rust on needle springs, or not care. If you do want to refinish the bluing, this is the pen for you. Some may also never notice the effect of raw brass on leather, but if you look closely, you can see that there will always be a reaction. It's just a matter of time and moisture (and maybe magnification). The pictures in the first blog showing this reaction are not rare by any means. The pictures just show an obvious case on a mid-50's Conn. Here is a recent blog on a mid-60's tenor rebuild that shows the same condition on every tone hole rim (plus a nice photo of an Eb pad that played a little stuffy, but I decided to replace as part of the rebuild).

https://stuffsax.blogspot.com/2018/11/1965-beaugniervito-tenor-rebuild.html

In other blogs, I used acids to change the patina on the entire brass saxophone and the bluing pen to blue the steel hinge rods during a rebuild. Neither are "necessary," but I'm rebuilding saxophones with the intention of long-term personal use, so I do it. It just takes a minute.

Mark
 

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Those are some very interesting "outside of the box" ideas. I have never heard of bluing hinge rods for example. A method I like to use on springs is similar to what you have described. On vintage saxes with rusty springs that are otherwise in good condition, I first remove the rust using 0000 steel wool which also removes any remaining "blued steel" color. Next I use gun bluing sold in small bottles at sporting goods stores applied to the spring using a Q-tip and wait for it to dry completely for about 5 minutes. This gives the raw steel a blue color, but it is a very flat, dull finish. Next I apply a layer of Renaissance Wax which dries almost instantly. That is then rubbed to a shine with a soft cloth and the old rusted spring looks like a shiny new blued steel spring again.
 

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Those are some very interesting "outside of the box" ideas. I have never heard of bluing hinge rods for example. A method I like to use on springs is similar to what you have described. On vintage saxes with rusty springs that are otherwise in good condition, I first remove the rust using 0000 steel wool which also removes any remaining "blued steel" color. Next I use gun bluing sold in small bottles at sporting goods stores applied to the spring using a Q-tip and wait for it to dry completely for about 5 minutes. This gives the raw steel a blue color, but it is a very flat, dull finish. Next I apply a layer of Renaissance Wax which dries almost instantly. That is then rubbed to a shine with a soft cloth and the old rusted spring looks like a shiny new blued steel spring again.
Question: the bluing as I understand it is primarily a result of thermal treatment of steel - hardening and tempering - but you are strictly talking about chemical treatment here to restore the looks and prevent corrosion?

Thanks!
 

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Question: the bluing as I understand it is primarily a result of thermal treatment of steel - hardening and tempering - but you are strictly talking about chemical treatment here to restore the looks and prevent corrosion?

Thanks!
I think two different ways of producing a thin layer of black iron oxide, Fe304. I don't know why it's any more resistant to oxidation other than I guess it's already oxidized...
 

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The chemical reaction using acids is generally referred to as "cold bluing." Mark-m has it. It is already corroded so it is hard to corrode it anymore. It is the thin layer of dormant corrosion that makes it harder for steel to rust and brass to form verdigris. Heat can be used with cold bluing to increase (faster reaction) the corrosion. Just don't use so much heat that the acid vaporizes. You will need your lungs when the rebuild is completed.

Steel wool works great for cleaning rust off of springs and then rebluing. The slow part is masking (if there is decent lacquer on the sax). If steel wool is in the same room as lacquered brass it will scratch it.

Mark
 

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Question: the bluing as I understand it is primarily a result of thermal treatment of steel - hardening and tempering - but you are strictly talking about chemical treatment here to restore the looks and prevent corrosion?

Thanks!
The liquid cold blueing agents we are talking about here are typically applying a selenium dioxide compound. Its not really the same as the hot blueing process and is really just for cosmetic touchup in most cases (on steel).

But if it works for this application who am I to judge.


That video was freaking me out too!
 

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The liquid cold blueing agents we are talking about here are typically applying a selenium dioxide compound. Its not really the same as the hot blueing process and is really just for cosmetic touchup in most cases (on steel).

But if it works for this application who am I to judge.


That video was freaking me out too!
Thanks, if I remember, the color change resulting from tempering is not as much a chemical reaction but a temperature-dependent change in displacement of carbon within the iron/steel (at least that's what I was taught many decades ago - and there is some oxidation going on of course).

I was just curious, there are so many ways of doing things different now, hard to keep up.
 

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Thanks, if I remember, the color change resulting from tempering is not as much a chemical reaction but a temperature-dependent change in displacement of carbon within the iron/steel (at least that's what I was taught many decades ago - and there is some oxidation going on of course).

I was just curious, there are so many ways of doing things different now, hard to keep up.
Been a while since I pretended to be a metallurgist but I seem to remember that the "hot" bluing (used by gunsmiths among others) is a straight chemical reaction with the salts in the dip mix at elevated temperatures to create a passive (ish) oxide coating. There are also colour effects seen just as a result of heat treatment building a thin oxide layer on steel that has some sort of interference effect that alters the colour if I remember right. Probably a ton of info out there for those that want to google it, I suspect none of its rocket science.

This is a technique for steel of course, chemically how this works on brass beats me, but if it works it works right?
 

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The above video freaked me out until I saw that it was a video loop. The horn looked to be ruined and yet the culprit continued? The stuff of nightmares.
Yes. It is designed to mislead. And no decent technician would remove that much medal from a tone hole. Most of tone hole levelling is completing what the factory did not do properly.

... Raw brass reacts with wet leather. If the leather is wet, the deterioration can be fast... It will produce "little chunks of stuff" (my scientific terminology) that will stick in the pad seats...
I don't totally agree. My 50 years of observations suggest that this happens very readily with some pads (even within months of brand new) but not others. I therefore tend to think that substandard pads use a leather where the corrosive tanning compounds have not been fully removed/neutralised. Use respected brands, high quality pads.
Other food for thought: Ammonia reacts with the copper in brass to make green corrosion (verdigris?). Ammonia is in the exhaled air of people who have bacterial infections in their airways or mouth.

... I've tried a couple of things to seal the raw brass. Wiping with tung oil works, but it take the tung oil more than a week to polymerize (solidify or "dry"), which is a pain to wait during a repad...
Heck. I once had an (expensive/) can of pure tung oil. It sure polymerised, within about 10 years - faster for the spillos outside the can - into a sticky substance resembling half-set varnish. I would not want that anywhere near my pads.

Regarding gun blueing compounds, such as selenic acid. This is a strong acid; I assume you are cleaning well before any contact with pads! At least some of these "blueing" compounds result in a finely rough surface, not unlike 1000 grit sandpaper, good for holding a subsequent protective wipe of oil. I wonder if such as surface may be quite abrasive towards pads.

It is a non issue in my experience. If the tonehole is cleaned occasionally with naptha, and/or a few passes of 1000 grit sandpaper, the bare brass will not be a problem. Of more concern after leveling toneholes is to remove any burrs around the edges.
I totally agree.
 

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... Some may never see rust on needle springs, or not care. If you do want to refinish the bluing, this is the pen for you... In other blogs, I used ... the bluing pen to blue the steel hinge rods during a rebuild. Neither are "necessary,"
I certainly would not allow a strong acid (from a bluing pen) to seep into the mounting of a needle spring. at the very least, I'd expect the resulting galvanic corrosion to eat away at the metal.

As I mentioned in my previous post, I suspect that bluing agents result in a finish that is somewhat abrasive. Not a problem for the exposed surface of a gun that is subsequently rubbed with oil, but I'm not sure it is the best idea for a bearing surface.
 

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The liquid cold blueing agents we are talking about here are typically applying a selenium dioxide compound...
I'm interested in a source for this information.

Google found "SELENIUM DIOXIDE is a white or creamy-white volatile lustrous crystal or crystalline powder with a pungent sour smell."
but that does not seem to describe the blue/black finish on steel, nor what it does to brass.

According to the MSDS sheet for the blueing pen - https://birchwoodcasey.com/files/datasheets/13201-Presto-Gun-Blue-Pen.pdf - the pen contains selenious acid, cupric sulphate and phosphoric acid. But I have no idea what that spsecifically does to steel, let alone brass.
 

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According to the MSDS sheet for the blueing pen - https://birchwoodcasey.com/files/datasheets/13201-Presto-Gun-Blue-Pen.pdf - the pen contains selenious acid, cupric sulphate and phosphoric acid. But I have no idea what that spsecifically does to steel, let alone brass.
I found this on a question and answer page. I cannot vouch for its accuracy, but it seems to make sense. "Liquid gun blue is a two step process, the first deposits a very thin copper layer from copper sulfate (the blue color ) and the copper is immediately turned black by the selenium in the solution. It must have free iron on the surface for the copper and the iron to swap so the copper plates onto the iron."

This site Finishing.com is also a useful source of information. I use it a lot for questions about electroplating.
 
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